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1
Ma, W. S., and W. Zhang. "Resonant Chaotic Dynamics of a Symmetric Cross-Ply Composite Laminated Plate Under Transverse and In-Plane Excitations." International Journal of Bifurcation and Chaos 30, no. 07 (June 15, 2020): 2050106. http://dx.doi.org/10.1142/s0218127420501060.
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The resonant chaotic dynamics of a symmetric cross-ply composite laminated plate are studied using the exponential dichotomies and an averaging procedure for the first time. The partial differential governing equations of motion for the symmetric cross-ply composite laminated plate are derived by using Reddy’s third-order shear deformation plate theory and von Karman type equation. The partial differential governing equations of motion are discretized into two-degree-of-freedom nonlinear systems including the quadratic and cubic nonlinear terms by using Galerkin method. There exists a fixed point of saddle-focus in the linear part for two-degree-of-freedom nonlinear system. The Melnikov method containing the terms of the nonhyperbolic mode is developed to investigate the resonant chaotic motions of the symmetric cross-ply composite laminated plate. The obtained results indicate that the nonhyperbolic mode of the symmetric cross-ply composite laminated plate does not affect the critical conditions in the occurrence of chaotic motions in the resonant case. When the resonant chaotic motion occurs, we can draw a conclusion that the resonant chaotic motions of the hyperbolic subsystem are shadowed for the full nonlinear system of the symmetric cross-ply composite laminated plate.
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Maksimov, F. E., M. M. Pevzner, A. Yu Petrov, S. B. Levchenko, V. A. Grigoriev, N. G. Baranova, and V. Yu Kuznetsov. "Age of the «cross-laminated sandy» stratum from the reference section Yar Sredny (Central Kamchatka) according to the paired 230Th /238U and 14C dating of peat." Доклады Академии наук 488, no. 3 (September 26, 2019): 288–93. http://dx.doi.org/10.31857/s0869-56524883288-293.
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For the first time, numerical radioisotope age were obtained for the “cross-laminated sandy” stratum, which is widespread in Neopeopleistocene reference sections of loose sediments from Central Kamchatka. Two peat layers, incorporated in the “cross-laminated sandy” stratum of the Yar Sredny, were studied. The results of their paired 230Th/238U and 14C dating are in good agreement with each other. According to the dating results, it was determined that the “cross-laminated sandy” stratum was deposited, apparently, in the range of about 50-40 thousand years ago, i.e. in the Late Pleistocene (MIS-3), and not in the Middle Pleistocene, about 400-300 thousand years ago, as previously thought.
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Lestari, Ratri Yuli. "CLT (Cross Laminated Timber): Produksi, Karakteristik dan Perkembangannya (CLT (Cross Laminated Timber): Production, Characteristics and Development)." Jurnal Riset Industri Hasil Hutan 9, no. 1 (October 1, 2017): 41–55. http://dx.doi.org/10.24111/jrihh.v9i1.3126.
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Cross laminated timber (CLT) is an engineered wood product as a laminated board that was arranged in cross order and applied as floor, roof, and wall. This product is an innovation in overcoming the scarce of wood material especially in large diameter and high quality as a building material. The review discusses the history of CLT, the characteristics, and its developments. CLT was first developed in Europe especially in Austria and Germany and then spread around the world. CLT has superiority in term of characteristics such as renewable, recyclable, easy to design and form, good insulation, energy efficient, fire resistance, good seismic characteristics, and also acts as a carbon sink that relieves the stress of global greenhouse gasses effect. CLT also has the strength that comparable to concrete and steel, and suitable for high rise building structure purposes. CLT is a prefabricated product and has advantages such as time saving, labor efficient, minimal post construction waste, and less disturbance to the environment during construction. CLT was developed outside Europe and reached North America, New Zealand and Indonesia. The barrier in adopting CLT are the lack of information of the products. One of the solution is to increase the awareness and the product knowledge.Keywords : architecture, building constructions, cross laminated timber, engineered wood
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Zheng, Yu Fang, and Li Qiong Deng. "Effect of Piezoelectricity on Nonlinear Free Vibration of Moderately Thick Laminated Piezoelectric Plates." Advanced Materials Research 239-242 (May 2011): 1223–26. http://dx.doi.org/10.4028/www.scientific.net/amr.239-242.1223.
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On the basis of laminated plate theory and piezoelectric theory, the nonlinear free vibration governing equations for symmetric cross-ply moderately thick laminated piezoelectric plates are established. The Galerkin procedure furnishes an infinite system of equations for time functions which are solved by the method of harmonic balance. In the numerical results, the influences of piezoelectric effect and various location of piezoelectric layer on the nonlinear vibrating frequency of the laminated piezoelectric plates are discussed.
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Wei, Shanyang, Huan Yang, Butong Gao, Haitao Cheng, Rongxiu Lu, and Lihui Dong. "Experimental research on temperature distribution and charring rate of typical components of wood structure building." Journal of Fire Sciences 40, no. 2 (January 21, 2022): 134–52. http://dx.doi.org/10.1177/07349041211073303.
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This study presents the fire performance of typical components of wood structure buildings. The wooden beams and floor slabs, quite common in wood structure buildings, were burned with different fire exposure times by a pool fire source. Then, the surface temperature evolution and the charring rate were recorded and analyzed. The results show that the flashover and re-ignition phenomenon occurred in all wood materials under the burning pool fires. The glulam beam cross-section was U-shaped, and the maximum charring rates of glulam beam, cross-laminated timber floor, and cross-laminated timber partition board were 0.833 mm/min, 1.538 mm/min, and 0.435 mm/min, respectively. It can be seen that the combustion behavior time of specimens with different cross-section thicknesses is different. If the thickness of the specimens is appropriately increased, their combustion behavior time can be significantly improved.
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Yan, Wei, W. Q. Chen, and B. S. Wang. "On time-dependent behavior of cross-ply laminated strips with viscoelastic interfaces." Applied Mathematical Modelling 31, no. 2 (February 2007): 381–91. http://dx.doi.org/10.1016/j.apm.2005.11.014.
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Zhang, B. Y., and W. Zhang. "Theory of Nonlinear Vibrations for Antisymmetric Cross-Ply Bistable Laminated Shells." Shock and Vibration 2021 (September 27, 2021): 1–31. http://dx.doi.org/10.1155/2021/3303512.
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In this paper, on the basis of taking the von Karman nonlinear factors into consideration, the constitutive equation of the antisymmetric cross-ply laminated composite was used to calculate the internal force and internal moment of the bistable structure, and the dynamic equilibrium equation and the compatible equation were constructed, respectively. The two equations were combined to establish a nonlinear dynamic model for the antisymmetric cross-ply laminated glass fiber resin bistable shell. Then, the finite element numerical simulation software ABAQUS was adopted to perform simulation modeling and numerical analysis on a series of bistable specimens, so as to study the impact of different geometric parameters on the frequencies, mode shapes, and other vibration characteristics of the antisymmetric laminated fiber resin bistable shell. Galerkin discretization was conducted on the vibration partial differential equation. Since there are only even-order partial differential terms of deflection w with respect to x and y in the vibration partial differential equation at this time, the form of series obtained by each term is the same, which simplifies the discretization of the dynamic equilibrium equation and the compatible equation. Finally, the two equations after discretization were merged to obtain the three-degree-of-freedom nonlinear ordinary differential equation of the antisymmetric cross-ply laminated glass fiber resin bistable shell. The system averaged equation was acquired by perturbation analysis through a multiscale method, and the periodic solution of the antisymmetric laminated bistable system was studied. Moreover, the system’s nonlinear dynamic behavior characteristics such as bifurcation and chaos were explored when the main resonance Ω is close to ω 1 and ω 2 , respectively, and the internal resonance is 1 : 2 : 3.
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Kukk, Villu, Targo Kalamees, and Jaan Kers. "The effects of production technologies on the air permeability and crack development of cross-laminated timber." Journal of Building Physics 43, no. 3 (August 7, 2019): 171–86. http://dx.doi.org/10.1177/1744259119866869.
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In a building envelope, the cross-laminated timber is often used as an air barrier layer. The objective of this study was to evaluate the impact of production technologies such as edge bonding, different initial moisture content of lamination and number of lamination layers (three and five) on the air permeability properties of the cross-laminated timber. Air leakage and crack area in cross-laminated timber panels were measured after the panels were conditioned in environments with different relative humidities in progressive steps from humid to dry environments (relative humidity 75% → relative humidity 43% → relative humidity 30% → relative humidity 15%). The test results showed that the five-layer specimens combined with initially drier laminations had the most considerable effect on avoiding air leakages through the panel. The greater number of layers helps to avoid any overlapping of gaps between laminations that are possible sources of air leakages. Based on the results, it is recommended to combine the technologies of using a larger number of layers together with initially drier laminations to minimise the growth of cracks on panel surfaces and avoid air leakages during the time of use.
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Zheng, Yu Fang, Yi Ming Fu, and Kai Qi. "Nonlinear Free Vibration for Cross-Ply Laminated Damaged Plates with Piezoelectric Actuators." Key Engineering Materials 324-325 (November 2006): 479–82. http://dx.doi.org/10.4028/www.scientific.net/kem.324-325.479.
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On the basis of the anisotropic damage theory and piezoelectric theory, the nonlinear free vibration governing equations for cross-ply laminated damaged plates with piezoelectric actuators are established. The Galerkin procedure furnishes an infinite system of equations for time functions which are solved by the method of harmonic balance. In the numerical results, the influences of damage parameters and piezoelectric effect on the nonlinear amplitude-frequency response curves of the laminated plates are discussed, which results reveal the inherent features about the coupled mechanics and electricity.
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Vamza, Ilze, Fabian Diaz, Peteris Resnais, Antra Radziņa, and Dagnija Blumberga. "Life Cycle Assessment of Reprocessed Cross Laminated Timber in Latvia." Environmental and Climate Technologies 25, no. 1 (January 1, 2021): 58–70. http://dx.doi.org/10.2478/rtuect-2021-0005.
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Abstract It is expected that Cross-laminated timber (CLT) and other engineered wood products will experience rapid growth in the coming years. Global population growth is requiring more housing units, at the same time the negative impact of construction industry cannot stay in the same level as today. Alternatives for concrete and steel reinforced structures are being explored. CLT has proven to be an excellent substitution for concrete regarding construction of buildings up to eight storeys high. In addition to much lower environmental impact, construction process using CLT takes significantly less time due to pre-cut shapes required for specific project. Despite mentioned benefits, there are considerable amount of CLT cuttings generated in this process. Due to irregular shape and small dimensions of these cuttings they are useless for further use in construction. By applying re-processing technology described in this paper, around 70 % of generated cuttings can be re-processed into new CLT panels. In this paper we are evaluating the environmental benefits of re-processing these cuttings into new CLT panels versus business-as-usual scenario with waste disposal. Life cycle assessment results showed significant reduction of environmental impact for the scenario of CLT cutting re-processing.
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Zhao, Kao Zhong, and Jian Jiang Liu. "Multiple Cross-Laminated Container Floor Temperature Field Based on ANSYS." Applied Mechanics and Materials 578-579 (July 2014): 83–88. http://dx.doi.org/10.4028/www.scientific.net/amm.578-579.83.
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Concrete composite beam floor cage floor as a new form , with a saving of steel and concrete , lighter weight, the advantages of high capacity , and has been more widely used in engineering. Therefore , to carry out the new concrete composite beam floor cages fire behavior for large spaces , large span areas is necessary. This article is the use of finite element software ANSYS multi-span composite floor beams cages fire tests to simulate life and death through SOLID70 unit features analog composite bottom plate before and after bursting floor temperature field and gives composite floor box overall temperature distribution along the rib cloud cover and the temperature of the beam cross-section of different heights - time curve , finally, the simulation results and experimental conditions were compared and analyzed , the main draw the following conclusions : the use of ANSYS thermal unit SOLID70 cell function and death can be simulated temperature distribution in case of fire concrete composite floor beam floor cages before and after bursting through the ribbed section of different heights temperature - time curve can be seen, the test results agree well with the simulation results ; testing process with increasing temperature , floor surface inlets, stacked boxes floor temperature contours directly reflects the law during the test floor surface appears inlets .
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Tylikowski, Andrzej. "Dynamic Stability of Nonlinear Antisymmetrically-Laminated Cross-Ply Rectangular Plates." Journal of Applied Mechanics 56, no. 2 (June 1, 1989): 375–81. http://dx.doi.org/10.1115/1.3176092.
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The dynamic stability problem is solved for rectangular plates that are laminated antisymmetrically about their middle plane and compressed by time-dependent deterministic or stochastic membrane forces. Moderately large deflection equations taking into account a coupling of in-plane and transverse motions are used. The asymptotic stability and almost-sure asymptotic stability criteria involving a damping coefficient and loading parameters are derived using Liapunov’s direct method. A relation between the stability of nonlinear equations and linearized ones is analyzed. An influence on the number of orthotropic layers, material properties for different classes of parametric excitation on stability domains is shown.
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Bakshi, Kaustav, and Dipankar Chakravorty. "Static and Dynamic Characteristics of Composite Conoidal Shell Roofs." Advances in Acoustics and Vibration 2013 (December 3, 2013): 1–9. http://dx.doi.org/10.1155/2013/539817.
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A thorough review of the existing literature reflects that forced vibration studies of laminated composite conoidal shells with complicated boundary conditions are missing. Hence, the present paper aims to fill the lacuna. A finite element code utilizing eight-noded doubly curved elements together with modified Sanders’ first approximation theory for thin shells is used to study the forced vibration behavior of moderately thin laminated composite conoidal shells subjected to three different uniformly distributed time-dependent forces. Newmark’s direct time integration method is used to solve the dynamic problem. Results obtained using the present code are compared with the values available in the literature, and a good agreement of the results confirms the accuracy of the proposed code. The transient responses of the laminated shell are studied meticulously for parametric variations like boundary conditions and stacking orders of cross and angle-ply laminates and are compared with bending responses of the shell to conclude on the necessity of the dynamic study.
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Romanov, P. G., and P. V. Sivtsev. "NUMERICAL EXPERIMENT ON SHEAR TESTING OF A CROSS-LAMINATED WOODEN ELEMENT." STRUCTURAL MECHANICS AND ANALYSIS OF CONSTRUCTIONS 306, no. 1 (February 2023): 56–64. http://dx.doi.org/10.37538/0039-2383.2023.1.56.64.
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A numerical experiment on shear tests of a model of a wooden CLT-panel revealed the possibility of visualizing the wave process of stress and strain propagation. Deformation as a process continuous in time is described discretely, in minimal time steps, with a visual display of a video sequence of positions in the space of the locus of tangent strain tensors. A qualitative and quantitative continuous wave pattern of stresses shows areas of the model volume where stress and strain waves arise and move. Stress isosurfaces are visualized. It is concluded that it is possible to divide the stress values expected in the numerical experiment into arbitrarily narrow intervals and separately monitor these processes in numerical models.
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Green, E. Rhian. "Response of a Fiber Composite Laminate to a Time-Varying Surface Line Load." Journal of Applied Mechanics 60, no. 1 (March 1, 1993): 217–21. http://dx.doi.org/10.1115/1.2900754.
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A symmetric cross-ply laminated plate consisting of four layers of a fiber-reinforced composite material is subjected to a time varying line load on its upper surface. The response at points remote from the application of the line load on both upper and lower surfaces of the plate is determined. Two different pulses are considered, namely a square pulse and a half-sine pulse. The significant parameter governing the nature of the response is the duration of the pulse.
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Thomas, Ed, Omar Espinoza, Rahul Bora, and Urs Buehlmann. "A Specialized Data Crawler for Cross-Laminated Timber Information Resources." Forest Products Journal 70, no. 3 (January 1, 2020): 256–61. http://dx.doi.org/10.13073/fpj-d-20-00017.
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Abstract The Internet is composed of more than 6.2 billion Web pages and grows larger every day. As the number of links and specialty subject areas grows, it becomes ever more difficult to find pertinent information. For some subject areas, special-purpose data crawlers continually search the Internet for specific information; examples include real estate, air travel, auto sales, and others. The use of such special-purpose data crawlers (i.e., targeted crawlers and knowledge databases) also allows the collection and analysis of agricultural and forestry data. Such single-purpose crawlers can search for hundreds of key words and use machine learning to determine if what is found is relevant. In this article, we examine the design and data return of such a specialty knowledge database and crawler system developed to find information related to cross-laminated timber (CLT). Our search engine uses intelligent software to locate and update pertinent references related to CLT as well as to categorize information with respect to common application and interest areas. At the time of this publication, the CLT knowledge database has cataloged nearly 3,000 publications regarding various aspects of CLT.
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Zhang, Yannian, Moncef L. Nehdi, Xiaohan Gao, and Lei V. Zhang. "Flexural Performance of Novel Nail-Cross-Laminated Timber Composite Panels." Applied Sciences 10, no. 17 (August 29, 2020): 5983. http://dx.doi.org/10.3390/app10175983.
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Cross-laminated timber (CLT) is an innovative wood panel composite that has been attracting growing interest worldwide. Apart from its economic benefits, CLT takes full advantage of both the tensile strength parallel to the wood grain and its compressive strength perpendicular to the grain, which enhances the load bearing capacity of the composite. However, traditional CLT panels are made with glue, which can expire and lose effectiveness over time, compromising the CLT panel mechanical strength. To mitigate such shortcomings of conventional CLT panels, we pioneer herein nail-cross-laminated timber (NCLT) panels with more reliable connection system. This study investigates the flexural performance of NCLT panels made with different types of nails and explores the effects of key design parameters including the nail incidence angle, nail type, total number of nails, and number of layers. Results show that NCLT panels have better flexural performance than traditional CLT panels. The failure mode of NCLT panels depends on the nail angle, nail type, and quantity of nails. A modified formula for predicting the flexural bearing capacity of NCLT panels was proposed and proven accurate. The findings could blaze the trail for potential applications of NCLT panels as a sustainable and resilient construction composite for lightweight structures.
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Gaarder, J. E., and T. D. Pettersen. "Built-in moisture in cross-laminated timber roofs – a field study." Journal of Physics: Conference Series 2069, no. 1 (November 1, 2021): 012051. http://dx.doi.org/10.1088/1742-6596/2069/1/012051.
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Abstract Cross-Laminated Timber (CLT) elements have had a growing popularity in recent years due to i.e. low carbon footprint, low weight and efficient construction time. However, the elements are sensitive to moisture and prone to organic growth if not treated properly or if used incorrectly. Roof slabs are particularly exposed, as they have a large area of exposure and the horizontal orientation doesn’t allow rainwater run-off. The efforts made to protect CLT-roofing elements by Norwegian contractors vary widely, as there are few guidelines and little long-term experience. A field study of CLT-roofs on existing buildings was conducted to investigate the conditions after some years in service. The study includes inspection and moisture measurements of CLT elements from the exterior side in 10 building projects 1-9 years old from two regions of Norway. The contractor of each project was interviewed in order to assess the extent of climate exposure and protection measures during construction. The results indicate a correlation between water content, building age and exposure level during construction. There is a clear indication that the drying time for built-in moisture in CLT roof constructions are slow. Keeping built-in moisture to a minimum is therefore paramount.
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Wang, Xue, Lihai Wang, Wenwen Ji, Quanling Hao, Guanghui Zhang, and Qingkai Meng. "Characterization of KH-560-Modified Jute Fabric/Epoxy Laminated Composites: Surface Structure, and Thermal and Mechanical Properties." Polymers 11, no. 5 (May 1, 2019): 769. http://dx.doi.org/10.3390/polym11050769.
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In this study, jute fabrics were used to reinforce epoxy resin to prepare laminated composites. KH-560 silane coupling agent modification was used to improve the interfacial compatibility between fibers and epoxy. The effects of different immersion times (0 min, 10 min, 30 min, 60 min, 90 min, and 120 min) on the jute fiber’s element content, crystal structure, and thermal stability, and the mechanical properties of laminated composites were studied. X-ray diffractometry (XRD) analysis showed that the KH-560 modification improved the crystallinity index (CI) and crystallite sizes (CS) of jute fibers. Scanning electron microscopy (SEM) analysis of the tensile fracture surfaces revealed a thick epoxy on the modified pulled fiber surfaces. Fourier transform infrared spectroscopy (FTIR) and energy dispersive spectrometer (EDS) analysis identified the presence of silicon and C–O–Si/Si–O–Si cross-linked structures on the surface of modified jute fibers. These cross-linked structures improved the thermal stability and mechanical properties of the laminated composites. When the immersion time was 60 min, the CI, CS, tensile strength, tensile modulus, flexural strength, and flexural modulus of the modified samples were 42.39%, 3.62 nm, 34.6 ± 1.1 MPa, 2.11 ± 0.12 GPa, 83.7 ± 1.8 MPa, and 4.08 ± 0.12 GPa, respectively, which were better than that of unmodified and other modified composites.
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Perković, Nikola, Jure Barbalić, Vlatka Rajčić, and Ivan Duvnjak. "Compressive Strength Properties Perpendicular to the Grain of Hollow Glue-Laminated Timber Elements." Polymers 14, no. 16 (August 19, 2022): 3403. http://dx.doi.org/10.3390/polym14163403.
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Timber is one of the fundamental materials of human civilization, it is very useful and ecologically acceptable in its natural environment, and it fits very well with modern trends in green construction. The paper presents innovative hollow glued laminated (GL) timber elements intended for log-house construction. Due to the lack of data on the behavior of the hollow timber section in compression perpendicular to the grain, the paper presented involves testing the compression strength of elliptical hollow cross-section glue-laminated timber specimens made of softwood and hardwood, as well as full cross-section glue-laminated softwood timber specimens. The experimental research was carried out on a total of 120 specimens. With the maximal reduction of 26% compared to the full cross-section, regardless of the type of wood and direction of load, the compression strength perpendicular to the grain of hollow specimens decreases by about 55% compared to the full cross-section, with the coefficient kc,90 equal to 1.0. For load actions at the edge and the middle of the element, kc,90 factors were obtained with a value closer to those obtained for full cross-section, which indicates the same phenomenology, regardless of cross-sectional weakening. At the same time, the factors in the stronger axis are lower by about 10%, and in the weaker axis by about 30% compared to those prescribed by the Eurocode. Experimental research was confirmed by FEM analysis. Comparative finite element analysis was performed in order to provide recommendations for future research and, consequently, to determine the optimal cross-section form of the hollow GL timber element. By removing the holes in the central part of the cross-section, the stress is reduced. The distance of the holes from the edges defines the local cracking. Finally, if the holes are present only in the central part of the element, the behavior of the element is more favorable.
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Nawab, Yasir, Frédéric Jaquemin, Pascal Casari, Nicolas Boyard, and Vincent Sobotka. "Evolution of chemical and thermal curvatures in thermoset-laminated composite plates during the fabrication process." Journal of Composite Materials 47, no. 3 (February 22, 2012): 327–39. http://dx.doi.org/10.1177/0021998312440130.
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Residual deformations and stresses formation in the thermoset-laminated composite is a frequently studied subject in the recent years. During fabrication, the laminated composites undergo chemical deformation during cross-linking and thermal deformation while cooling. In thin laminates, due to large displacements and complex evolution of shape, these deformations can only be explained by using nonlinear strain–displacement relationship. In the present article, we calculated together for the first time, the thermal and chemical deformations occurring in carbon/epoxy laminates by considering a nonlinear geometrical approach to understand the evolution of shape and hence residual stresses induced during fabrication process. The effect of fibre fraction on the chemical and thermal deformations is studied as well.
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Das Neogi, Sanjoy, Amit Karmakar, and Dipankar Chakravorty. "Study of Dynamic Behavior of Multilayered Clamped Composite Skewed Hypar Shell Roofs under Impact Load." Journal of Engineering 2013 (2013): 1–10. http://dx.doi.org/10.1155/2013/192176.
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With advancement in the field of structural engineering, hunt for smarter materials has channelised the research towards the application of composite material. It is the high specific weight and specific stiffness of this material that have drawn the interest of different industrial sectors. Civil engineers also picked up composites to use it as a roofing material. Laminated composite shells, which can cover large column-free area and reduces dead weight of structure, show vulnerability under sudden impact due to their low transverse shear resistances. This study utilises finite element tool to investigate the dynamic response of a multilayered laminated composite hypar shells for fully clamped boundary condition. This class of shells is unique in a sense that the curvature has only the radius of cross curvature and these shells do not admit easy closed form solution particularly when the boundary conditions are complicated. Contact behavior of impactor and impacted mass has been modeled by modified Hertzian contact law and time-dependent equations are solved using Newmark’s time integration technique. Basic aim is to analyse the shell for symmetrically placed multilayered angle and cross ply lamination under different impact velocities.
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Daneshvar, Hossein, Mahboobeh Fakhrzarei, Fernanda Imamura, Yuxiang Chen, Lijun Deng, and Ying Hei Chui. "Structural Analysis and Design of Sustainable Cross-Laminated Timber Foundation Walls." Buildings 12, no. 7 (July 9, 2022): 979. http://dx.doi.org/10.3390/buildings12070979.
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There is widespread enthusiasm toward utilizing mass timber panels (MTP), mainly cross-laminated timber (CLT), in construction, including for the basements of low-rise buildings. CLT is deemed a sustainable alternative to the widely used concrete foundation walls due to significant advantages such as less vulnerability to cracking due to uneven load distribution and presence of concentrated loads, higher thermal resistance, less construction time due to whole-wall prefabrication and installation, and less detrimental environmental effects. This study is part of an extensive research program aimed at developing the structural analysis and design concepts and methodology for constructing house foundation walls using MTPs, focusing on the usage of CLT. After comparison of CLT basements with their equivalent concrete ones from the sustainability point of view, and a brief discussion on geotechnical and hygrothermal considerations, the main theme of the article includes the structural analysis and design methodology, requirements, and the procedure to achieve a reliable and efficient design of a CLT basement. A simplified analysis procedure to design the laminate thicknesses and the number of layers in CLT foundation walls for different scenarios considering various variables such as soil type and backfill height is discussed, and results in the form of pre-engineered design tables are provided. The findings of this study demonstrate that, depending on the soil type and backfill height, 3–7-ply CLT panels would be needed for net wall heights of up to 3 m. Additionally, advanced finite element analyses are performed on sample architypes to validate the simplified analysis procedure used for design. It is shown that the proposed analysis procedure and the pre-engineered tables produce conservative and efficient results.
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Darmawan, Teguh, Adik Bahanawan, Danang S. Adi, Wahyu Dwianto, and Naresworo Nugroho. "FIXATION PROCESS OF LAMINATED BAMBOO COMPRESSION FROM CURVED CROSS-SECTION SLATS." Indonesian Journal of Forestry Research 8, no. 2 (October 31, 2021): 159–71. http://dx.doi.org/10.20886/ijfr.2021.8.2.159-171.
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Removing the outer part of bamboo for manufacturing flat bamboo lamination has disadvantage on the density of the product. The purpose of this experiment was to investigate the fixation of compressed bamboo from curved cross-section slats. The compression of bamboo slats using densification technique was aimed for uniform density. Furthermore, steam treatments were conducted to fix the deformation. The compressed bamboo slats revealed that the density of the samples at the bottom parts increased from 0.40–0.56 g/cm3 to 0.89–1.05 g/cm3 after pressing with a compression level between 46.98–63.97%, while the samples in the middle parts increased from 0.70–0.83 g/cm3 to 1.02–1.18 g/cm3 with the compression level of 32.92–41.50%. These results were slightly higher than that of the upper parts, which was between 0.91–0.98 g/cm3. The recovery of set decreased and the weight loss increased with increasing temperature and steam treatment time. Fixation of compressive deformation could be achieved at 160°C within 60 minutes. The bottom parts of samples experienced a slightly greater weight loss compared to the middle parts, i.e. 8.38% and 7.49%, respectively. The anatomical structure of bamboo tended to deform during densification process. Furthermore, the steam treatments affected the colour of densified bamboo which became darker. From this experiment, it can be concluded that the manufacture of laminated bamboo from bamboo slats can be uniformed in strength by equalizing the density at the bottom and middle with the upper parts through the densification technique. However, further research should be conducted to know the delamination and shear strength of the bamboo lamination.
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Robeller, Christopher, and Niklas Von Haaren. "Recycleshell: Wood-only Shell Structures Made From Cross-Laminated Timber (CLT) Production Waste." Journal of the International Association for Shell and Spatial Structures 61, no. 2 (June 1, 2020): 125–39. http://dx.doi.org/10.20898/j.iass.2020.204.045.
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The article describes a new construction system for shell structures made from door- and window cut-offs resulting from cross laminated timber (CLT) production lines. For the first time, form-fitting fasteners made of beech laminated veneer lumber are used in a shell made of engineered wood plates, enabling a particularly simple, fast and precise construction. The efficient planning and production of a multitude of differently shaped elements is made possible by a CAD plug-in developed by the authors. The article presents the general application possibilities and limitations of the system, as well as the case study of a shell demonstrator with a span of 12 meters, built from 229 hexagonal plates. A detailed structural analysis is presented for the demonstrator, including an experimental load test to confirm the FEM results.
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Kormanikova, Eva, Kamila Kotrasova, Jozef Melcer, and Veronika Valaskova. "Numerical Investigation of the Dynamic Responses of Fibre-Reinforced Polymer Composite Bridge Beam Subjected to Moving Vehicle." Polymers 14, no. 4 (February 20, 2022): 812. http://dx.doi.org/10.3390/polym14040812.
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In modern industry, heavy traditional materials are being substituted with light and strong fibre-reinforced polymer composite materials. Bridges and railroads made of composite laminates are considerably affected by traffic loads. Therefore, it is very important to analyse this effect which would find practical applications in engineering designs. This paper explains the theoretical formulation that governs the dynamic response of a composite beam subjected to a moving load. The governing equations for the dynamic effect on the laminated composite bridge beam are explained here. The main theories in the micro–macro modelling of composite laminates are also described in the paper. Within the macro modelling, the Classical Laminate and Shear Deformation Laminate Theory of beams are presented. The symmetric cross-ply laminated bridge, made of boron/epoxy is under consideration. The computational two-dimensional model of the vehicle is adopted. The governing equations for the dynamic effect on the laminated composite bridge beam are explained. The calculation of the time response of the bridge for the characteristic speeds of the vehicle is performed in the environment of the MATLAB software. The maximum dynamic magnification factor for the dynamic analysis of a composite beam is found.
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Cheng, Chi-Honn, Cheuk-Lun Chow, Tsz-Kit Yue, Yiu-Wah Ng, and Wan-Ki Chow. "Smoke Hazards of Tall Timber Buildings with New Products." Encyclopedia 2, no. 1 (March 8, 2022): 593–601. http://dx.doi.org/10.3390/encyclopedia2010039.
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Timber buildings can now stand very tall using new products. As timber materials are expected to be easily ignitable, the fire hazard of timber is a concern. Charring of the timber surface would maintain structural stability, but would also be accompanied by smoke. Although treating timber products with fire retardants would delay the ignition time under low radiative heat flux, toxic combustion products and unburnt fuel would be emitted immediately upon burning. More smoke and higher toxic gas concentrations such as carbon monoxide would be given off upon burning some fire retardants under high flashover heat fluxes. Due to the fast upward movement of smoke under stack effect, spreading of toxic smoke in tall timber buildings would lead to a hazardous environment. Engineered timber consists of derivative timber products. New engineered timber products are manufactured with advanced technology and design, including cross-laminated-timber (CLT), laminated veneer lumber (LVL) and glue-laminated timber (Glulam). The fire behaviour of timber products has been studied for several decades. However, the smoke hazards of using new timber products in building construction should be monitored. The objective of this study is to inspire stakeholders in fire safety of timber buildings, inter alia smoke hazards, to use new timber products to build tall buildings.
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Sekhavatjou, Mohammad, Mojtaba Azhari, and Saeid Sarrami-Foroushani. "Bubble Complex Finite Strip Method in the Stability and Vibration Analysis of Orthotropic Laminated Composite Plates." International Journal of Applied Mechanics 12, no. 09 (November 2020): 2050106. http://dx.doi.org/10.1142/s1758825120501069.
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In this study, a bubble complex finite strip method (BCFSM) with the higher-order zigzag theory is formulated for mechanical buckling and free vibration analysis of laminated composite plates, including cross-ply and angle-ply laminates. Few studies have been done to obtain the analytical solutions for clamped and free boundary conditions in the longitudinal and transverse edges. Therefore, this study, for the first time, investigates the effects of various boundary conditions on the stability and vibration results of laminated composite plates subjected to axial or pure shear forces with the use of higher-order zigzag theory and BCFSM. Following this, both the interlaminar continuity conditions of transverse shear stresses and the shear-free surface conditions are satisfied by applying a cubic displacement and a zigzag linear varying displacement with the same number of unknowns as the first-order shear deformation theories. Moreover, the effects of width-to-thickness ratio, fiber orientation, number of modes, different dimensional ratios of the plate, and finally, the number of layers are investigated through numerical examples. The bubble shape functions are exploited in the transverse direction to improve the convergence of the method. Finally, the shearing and axial interaction diagrams of composite laminated plates are presented for various types of boundary conditions.
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Morandi, F., A. Santoni, P. Fausti, and M. Garai. "Determination of the dispersion relation in cross-laminated timber plates: Benchmarking of time- and frequency-domain methods." Applied Acoustics 185 (January 2022): 108400. http://dx.doi.org/10.1016/j.apacoust.2021.108400.
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SARANGI, SAROJ KUMAR, and M. C. Ray. "SMART CONTROL OF NONLINEAR VIBRATIONS OF LAMINATED PLATES USING ACTIVE FIBER COMPOSITES." International Journal of Structural Stability and Dynamics 12, no. 06 (December 2012): 1250050. http://dx.doi.org/10.1142/s0219455412500502.
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This paper deals with the geometrically nonlinear dynamic analysis of smart laminated composite plates integrated with the patches of active constrained layer damping (ACLD) treatment. The constraining layer of the ACLD treatment is made of active fiber composite (AFC) materials. The Von Kármán type nonlinear strain–displacement relations and the first-order shear deformation theory (FSDT) are adopted in deriving the coupled electromechanical nonlinear finite element (FE) model. The Golla–Hughes–McTavish (GHM) method is implemented to model the constrained viscoelastic layer of the ACLD treatment in time domain. Symmetric/antisymmetric cross-ply and antisymmetric angle-ply laminated substrate plates are considered in the numerical analyses. The results indicate that the ACLD patches significantly improve the damping characteristics of the plates for suppressing the geometrically nonlinear transient vibrations of the plates. The effects of variation of piezoelectric fiber orientation in the AFC constraining layer on the control authority of the ACLD patches have also been investigated.
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Nawab, Yasir, Frédéric Jacquemin, Pascal Casari, Nicolas Boyard, and Vincent Sobotka. "Shape Evolution of Carbon Epoxy Laminated Composite during Curing." Key Engineering Materials 504-506 (February 2012): 1145–50. http://dx.doi.org/10.4028/www.scientific.net/kem.504-506.1145.
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The laminated composites undergo chemical deformation on cross-linking and thermal deformation while cooling during fabrication process. In thin laminates, due to large displacements and complex shape evolution, these deformations can only be explained by using nonlinear strain-displacement relationship. In the present article, the thermal and chemical deformations occurring in carbon/epoxy laminates are calculated together for the first time by considering a non-linear geometrical approach, to understand the evolution of shape and hence residual stresses induced during fabrication process.
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Nilsson, Erik, Sylvain Ménard, Delphine Bard Hagberg, and Klas Hagberg. "Effect of Bearing Direction and Mounting Techniques on Cross-Laminated Timber Elements in the Field." INTER-NOISE and NOISE-CON Congress and Conference Proceedings 265, no. 6 (February 1, 2023): 1936–46. http://dx.doi.org/10.3397/in_2022_0274.
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Vibration reduction index (Kij) measurements in the field have some challenges compared to laboratory measurements. Firstly, the measurement requires access to a construction site during the short time span when the cross-laminated timber (CLT) elements are apparent. Secondly, building contractors are often on a tight time schedule. Therefore, it is important to find a solution that minimizes the measurement time on site. Moreover, Kij measurements in the field include several types of junctions with different bearing directions which may be of importance. This paper aims to evaluate two different mounting techniques with accelerometers on CLT elements and to discuss how the bearing direction could affect the vibration level difference of junctions. Measurement data indicates few deviations between mounting techniques with bee wax or double-sided adhesive tape when accelerometers are attached on CLT elements. Furthermore, field measurements indicate that the vibration level will decrease with an increased number of lamellas over the same CLT element. Double-sided adhesive tape is an adequate substitute for bee wax in the field for mounting accelerometers on CLT elements, with some limitations for high frequencies. Measurement data concludes that the bearing direction of CLT elements can influence the vibration reduction index of a junction.
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Junnila, R. M., and G. M. Young. "The Paleoproterozoic upper Gowganda Formation, Whitefish Falls area, Ontario, Canada: subaqueous deposits of a braid delta." Canadian Journal of Earth Sciences 32, no. 2 (February 1, 1995): 197–209. http://dx.doi.org/10.1139/e95-016.
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The upper Gowganda Formation is part of the Paleoproterozoic Huronian Supergroup (ca. 2.5–2.2 Ga) of the north shore of Lake Huron. The upper Gowganda Formation rests with sharp conformable contact on glaciogenic rocks of the lower Gowganda Formation and is gradational with cross-bedded sandstones of the overlying Lorrain Formation. At the southern margin of the Huronian fold belt, in the Whitefish Falls area, the upper Gowganda Formation is 380–750 m thick, and consists of four coarsening-upward cycles from 30 to 300 m in thickness. Each is comprised of the succession (a) laminated argillite deposited from suspension on the prodelta, (b) argillite and cross-laminated sandstone laid down on the delta front by normal fluvial input and flood episodes, (c) fine-to coarse-grained, cross-bedded sandstone formed as distributary-mouth sand sheets influenced by shallow marine processes. Abundant soft-sediment deformation indicates rapid sedimentation and (or) contemporaneous fault-related seismicity. Erosional contacts between cycles resulted from marine reworking as sediment supply diminished. Each coarsening-upward cycle is interpreted as the subaqueous deposits of a braid delta that prograded into a moderately wave-influenced, tectonically active marine basin. In some respects, the succession of the deltaic deposits is comparable to those formed during the postglacial evolution of the Mississippi delta, but it is likely that the fluvial regime at the time of deposition of the Gowganda Formation was dominantly braided.
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Harris, Peter, Grzegorz Litak, Joanna Iwaniec, and Chris R. Bowen. "Recurrence Plot and Recurrence Quantification of the Dynamic Properties of Cross-Shaped Laminated Energy Harvester." Applied Mechanics and Materials 849 (August 2016): 95–105. http://dx.doi.org/10.4028/www.scientific.net/amm.849.95.
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The paper examines the dynamic properties of bistable cross-shaped laminate plates for broadband energy harvesting applications by converting mechanical vibration energy into the electrical power output. Bistable laminates plates coupled to piezoelectric transducers were excited by application of harmonic excitations and exhibited a range of vibration patterns. The vibration patterns included single-well oscillations and snap-through vibrations of both periodic and chaotic character; such vibration patterns led to a different power output. Classical spectral analysis of measured voltage, displacement and velocity time histories indicated the presence of a variety of nonlinear and chaotic phenomena. As a result, an analysis of the measured displacement and voltage time histories was carried out with the use of the Recurrence Plots and the Recurrence Quantification Analysis methods. The Recurrence Plots method was used for detection of qualitative changes in the dynamic behaviour of the non-linear harvesting system. In order to facilitate interpretation of piezoelectric voltage and laminate displacement, a detailed analysis using Recurrence Plots, Recurrence Quantification Analysis was employed.
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Hariz, Tengku Muhammad Renzy, Yusuf Sudo Hadi, Muhammad Adly Rahandi Lubis, Muhammad Iqbal Maulana, Rita Kartika Sari, and Wahyu Hidayat. "Physical and Mechanical Properties of Cross-Laminated Timber Made of a Combination of Mangium-Puspa Wood and Polyurethane Adhesive." Jurnal Sylva Lestari 11, no. 1 (January 6, 2023): 37–65. http://dx.doi.org/10.23960/jsl.v11i1.645.
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This study aimed to evaluate the physical and mechanical properties of cross-laminated timber (CLT) characteristics from mangium (Acacia mangium) and puspa (Schima wallichii) woods and their combination using polyurethane (PU 1.2) adhesives. The manufacture of CLT began with basic adhesive characterization and thermo-mechanical analysis. Wood material’s physical and chemical properties were also tested with its response to the PU 1.2 wettability. The CLT (100 ´ 30 ´ 3.60) cm3 was manufactured with 160 g/m2 glue spread at a pressure of 0.80 MPa for 200 minutes. The CLT panels were characterized refers to the JAS 3079 standard. The results show that PU 1.2 had a gelatination time of 182.1 minutes at 25°C, was able to form urethane groups, and experienced an increase in storage modulus at 35°C. Mangium and puspa woods have different physical and chemical properties, but they interact similarly with PU 1.2 wettability. Puspa CLT panel has a higher density than mangium but lower dimensional stability. The bending mechanical properties of hybrid puspa-mangium-puspa CLT were able to match puspa CLT and have one sample of shear strength that met the JAS 3079 standard in both grain directions. Therefore, hybrid puspa-mangium-puspa CLT has the potential to be developed to improve its dimensional stability and mechanical properties. Keywords: Acacia mangium, cross-laminated timber, layer combination, polyurethane adhesive, Schima wallichii
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Naldrett, Dana L. "Sedimentology, Stratigraphy and Micropaleontology of Pre- and Early-Champlain Sea Fine-Grained Facies from the Foster Sand Pit, Ottawa, Ontario." Géographie physique et Quaternaire 42, no. 2 (December 18, 2007): 181–89. http://dx.doi.org/10.7202/032724ar.
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ABSTRACT The Foster sand pit exposes pre- to late-Champlain Sea sediments containing 4 litho/biofacies. These are, from oldest to youngest: Faciès 1- cross-stratified sand and diamicton deposited as late-glacial, ice-proximal subaqueous outwash. Faciès 2- laminated silt and clay rhythmites with a sparse Candona cf. C. subtriangulata ostracode fauna deposited in a deep, proglacial lake preceding the Champlain Sea, Fades 3- massive to rarely laminated silty clay with dominant foraminifera Elphidium bartletti, Protelphidium orbiculare and Cassidulina crassa represents the first glaciomarine deposition in Champlain Sea water 30-100 m deep with a paleosalinity of 22-33 %o. Faciès 4- mixed bedding of sand and mud, with a microfossil assemblage dominated by the Elphidium/Protelphidium complex representing an intertidal offlap sequence. Water depths during deposition of Faciès 4 dropped to 10-30 m. and paleosalinity dropped to 18-28 %o.. This study recognizes a pre-Champlain Sea proglacial lake, assigns subaqueous outwash deposits to an earlier time than previously believed and documents changes in bottom water characteristics of the early Champlain Sea based on sedimentary and microfossil evidence.
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Bezabeh, Matiyas A., Solomon Tesfamariam, Siegfried F. Stiemer, Marjan Popovski, and Erol Karacabeyli. "Direct Displacement-Based Design of a Novel Hybrid Structure: Steel Moment-Resisting Frames with Cross-Laminated Timber Infill Walls." Earthquake Spectra 32, no. 3 (August 2016): 1565–85. http://dx.doi.org/10.1193/101514eqs159m.
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This study proposes an iterative direct displacement based design method for a novel steel-timber hybrid structure. The hybrid structure incorporates cross-laminated timber (CLT) shear panels as an infill in steel moment-resisting frames. The proposed design method is applied to design three-, six-, and nine-story hybrid buildings, each with three bays and a CLT-infilled middle bay. Nonlinear time history analysis, using 20 earthquake ground motion records, is carried out to validate the performance of the design method. The results indicate that the proposed method effectively controls the displacements due to seismic excitation of the hybrid structure.
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Herrmann, Johannes, Torsten Kühn, Tjorven Müllenstedt, Siham Mittelstedt, and Christian Mittelstedt. "A Higher Order Shear Deformation Approach to the Local Buckling Behavior of Moderately Thick Composite Laminated Beams." International Journal of Structural Stability and Dynamics 18, no. 11 (October 22, 2018): 1850139. http://dx.doi.org/10.1142/s0219455418501390.
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This paper presents a novel closed-form analytical approximate solution for the local buckling behavior of composite laminated beams under uniform axial compression. The laminates that constitute the segments of the beam cross-sections (i.e. webs and flanges) are assumed to be moderately thick so that the current analysis approach is based on Reddy’s third-order shear deformation theory? (TSDT). The idealization relies on the discrete plate approach, meaning that the individual segments are separated from the beam cross-section, and the local buckling behavior is analyzed by performing a TSDT-based plate buckling analysis by assuming adequate boundary conditions for webs and flanges. At those edges where the segment under consideration has been separated from the cross-section, elastic restraints are applied to the stiffness values of which depend on the geometric and material properties of the adjacent segments. The analysis approach uses the principle of minimum elastic potential of the considered discrete plate in the buckled state and relies on rather simple shape functions for the buckling modes, thus eventually enabling a closed-form analytical approximate solution that does not necessitate any numerical means of evaluation. Results are generated for a number of I-beam configurations and are compared to results generated in the framework of classical laminated plate theory (CLPT) and first-order shear deformation theory (FSDT). It is shown that the present new approach delivers reliable results without any significant computational effort and thus can be recommended for all engineering analysis tasks where computational time and effort are deciding factors in day-to-day engineering work, such as systematic optimizations or extensive parametric studies.
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Sofiyev, A. H. "The buckling of a cross-ply laminated non-homogeneous orthotropic composite cylindrical thin shell under time dependent external pressure." Structural Engineering and Mechanics 14, no. 6 (December 25, 2002): 661–77. http://dx.doi.org/10.12989/sem.2002.14.6.661.
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Świrska-Perkowska, Jadwiga, Anna Wicher, Sławomir Pochwała, Stanisław Anweiler, and Michał Böhm. "Doweled cross Laminated Timber (DCLT) Building Air Tightness and Energy Efficiency Measurements: Case Study in Poland." Energies 15, no. 23 (November 29, 2022): 9029. http://dx.doi.org/10.3390/en15239029.
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A contemporary challenge for the construction industry is to develop a technology based on natural building materials which at the same time provides high energy efficiency. This paper presents the results of an airtightness test and a thermal imaging study of a detached house built with technology using cross laminated dowelled timber panels. The thermal conductivity coefficients of the wood wool used to insulate the walls and ceiling of the building have also been measured, the linear heat transfer coefficients of the structural nodes have been numerically determined, and calculations have been made regarding the energy efficiency of the building. On the basis of the research, it was found that the air exchange rate in the analyzed building n50 is at the level of 4.77 h−1. Air leaks were also observed in the places of connection of longitudinal walls with the roof and at the junction of window frames with external walls. The experimentally determined thermal conductivity coefficient of the wood wool was ~10% higher than that declared by the manufacturer. Calculations for the energy performance certificate showed that an increase of ~10% in the thermal conductivity coefficient of the wood wool used to insulate the building results in a heating demand increase of 2.1%. It was also found that changing the value of the parameter n50 from 1.0 h−1 to 4.77 h−1 leads to a 40.1% increase in heat demand for heating the building. At the same time, the indicators for final energy demand EK and non-renewable primary energy demand EP increase by 18.1%.
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Sayed, M., and A. A. Mousa. "Vibration, Stability, and Resonance of Angle-Ply Composite Laminated Rectangular Thin Plate under Multiexcitations." Mathematical Problems in Engineering 2013 (2013): 1–26. http://dx.doi.org/10.1155/2013/418374.
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An analytical investigation of the nonlinear vibration of a symmetric cross-ply composite laminated piezoelectric rectangular plate under parametric and external excitations is presented. The method of multiple time scale perturbation is applied to solve the nonlinear differential equations describing the system up to and including the second-order approximation. All possible resonance cases are extracted at this approximation order. The case of 1 : 1 : 3 primary and internal resonance, whereΩ3≅ω1,ω2≅ω1, andω3≅3ω1, is considered. The stability of the system is investigated using both phase-plane method and frequency response curves. The influences of the cubic terms on nonlinear dynamic characteristics of the composite laminated piezoelectric rectangular plate are studied. The analytical results given by the method of multiple time scale is verified by comparison with results from numerical integration of the modal equations. Reliability of the obtained results is verified by comparison between the finite difference method (FDM) and Runge-Kutta method (RKM). It is quite clear that some of the simultaneous resonance cases are undesirable in the design of such system. Such cases should be avoided as working conditions for the system. Variation of the parametersμ1,μ2,α7,β8,ω1,ω2,f1,f2leads to multivalued amplitudes and hence to jump phenomena. Some recommendations regarding the different parameters of the system are reported. Comparison with the available published work is reported.
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Churchill, Claire, Bernd Nusser, and Christian Lux. "Dilatation wave velocities estimated from the plateau in sound insulation of cross-laminated timber (CLT) plates." INTER-NOISE and NOISE-CON Congress and Conference Proceedings 265, no. 4 (February 1, 2023): 3850–57. http://dx.doi.org/10.3397/in_2022_0546.
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There are four inherent problems when predicting the airborne sound insulation of cross-laminated timber (CLT) plates. (1) The internal loss factor of wood products is high and therefore difficult to measure using the structural reverberation time technique. (2) Solid wood is a low-density building material compared to reinforced concrete or masonry construction. (3) Timber is orthotropic. (4) Orthotropic behaviour includes low shear moduli. CLT plates, similarly to thick masonry or concrete plates, exhibit thick plate behaviour in the high frequency range (f>1600Hz). The high frequency sound insulation data of nine plates is examined. Transitions to a thick plate seems to occur in all measurements. However, a clearly observable plateau is only visible for six of the nine plates. Simple methods are applied to extract information about the CLT plates from this high frequency (f>1600Hz) measured data. The data extracted from the plate is compared to typical values for equivalent isotropic plates, where the bending stiffness is assumed to be B_iso=√(B_x B_y ). The results are discussed in the context of laboratory measurement of sound insulation.
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Naidu Balireddy, Somi, Pitchaimani Jeyaraj, Lenin Babu Mailan Chinnapandi, and Ch V. S. N. Reddi. "Effect of lamination schemes on natural frequency and modal damping of fiber reinforced laminated beam using Ritz method." International Journal for Simulation and Multidisciplinary Design Optimization 12 (2021): 15. http://dx.doi.org/10.1051/smdo/2021016.
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The current study focussed on analysing natural frequency and damping of laminated composite beams (LCBs) by varying fiber angle, aspect ratio, material property and boundary conditions. Ritz method with displacement field based on the shear and normal deformable theory is used and the modal damping is calculated using modal strain energy method. Effects of symmetric angle-ply and cross-ply, anti symmetric cross-ply, balanced and quasi-isotropic lay up schemes on modal damping are presented for the first time. Results revealed that influence of lay-up scheme on natural frequencies is significant for the thin beams while the modal damping of the thin beams are not sensitive to lay-up scheme. However, the lay-up scheme influences the damping significantly for the thick beams. Similarly, high strength fiber reinforced LCBs have higher natural frequency while low strength fiber reinforced LCBs have higher damping due to the better fiber-matrix interaction.
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Hong, Shu, Zhongji Gu, Ling Chen, Ping Zhu, and Hailan Lian. "Synthesis of phenol formaldehyde (PF) resin for fast manufacturing laminated veneer lumber (LVL)." Holzforschung 72, no. 9 (September 25, 2018): 745–52. http://dx.doi.org/10.1515/hf-2017-0184.
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AbstractPhenol formaldehyde (PF) resin is a well-tried adhesive for manufacturing laminated veneer lumber (LVL). PF has a high bonding strength, good cold pressing property and contributes a lot to the high production efficiency of LVL. In the present paper, PFs were synthesized at three different alkaline condition levels with a molar formaldehyde to phenol (F/P) ratio of 2.25. The bonding strength of PFs was not influenced by the alkalinity. Compared with PFs synthesized under alkalinity of 1 and 4%, PF with 8% alkalinity formed a resin with a high mole mass (MM), uniform mole mass distribution (MMD) and a high cross-linking density. With PF8%, the cold pressing property could be shortened from 30 to 12 min in the winter time. Cured PF8%had a higher cross-linking density than PF1%and PF4%. PF8%has a high potential for industrial production of LVL.
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Alonso, Unai, Fernando Veiga, Alfredo Suárez, and Teresa Artaza. "Experimental Investigation of the Influence of Wire Arc Additive Manufacturing on the Machinability of Titanium Parts." Metals 10, no. 1 (December 22, 2019): 24. http://dx.doi.org/10.3390/met10010024.
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The manufacturing of titanium airframe parts involves significant machining and low buy-to-fly ratios. Production costs could be greatly reduced by the combination of an additive manufacturing (AM) process followed by a finishing machining operation. Among the different AM alternatives, wire arc additive manufacturing (WAAM) offers deposition rates of kg/h and could be the key for the production of parts of several meters economically. In this study, the influence of the manufacturing process of Ti6Al4V alloy on both its material properties and machinability is investigated. First, the mechanical properties of a workpiece obtained by WAAM were compared to those in a conventional laminated plate. Then, drilling tests were carried out in both materials. The results showed that WAAM leads to a higher hardness than laminated Ti6Al4V and satisfies the requirements of the standard in terms of mechanical properties. As a consequence, higher cutting forces, shorter chips, and lower burr height were observed for the workpieces produced by AM. Furthermore, a metallographic analysis of the chip cross-sectional area also showed that a serrated chip formation is also present during drilling of Ti6Al4V produced by WAAM. The gathered information can be used to improve the competitiveness of the manufacturing of aircraft structures in terms of production time and cost.
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UNGBHAKORN, VARIDDHI, and NUTTAWIT WATTANASAKULPONG. "STRUCTURAL SIMILITUDE AND SCALING LAWS OF ANTI-SYMMETRIC CROSS-PLY LAMINATED CYLINDRICAL SHELLS FOR BUCKLING AND VIBRATION EXPERIMENTS." International Journal of Structural Stability and Dynamics 07, no. 04 (December 2007): 609–27. http://dx.doi.org/10.1142/s0219455407002459.
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Developed herein are the scaling laws for physical modeling of anti-symmetric cross-ply laminated circular cylindrical shells for buckling and free vibration experiments. In the absence of experimental data, the validity of the scaling laws is verified by numerical experiments. This is accomplished by calculating theoretically the buckling loads and fundamental frequencies of the model and substituting into the scaling laws to obtain the corresponding values of the prototype. The predicted values of the prototype from the scaling laws are then compared with existing closed-form solutions. Examples for the complete similitude cases with various stacking sequences, number of plies, and length-to-radius ratios show exact agreement. The derived relationships between the model and prototype will greatly facilitate and reduce the need for costly experiments. In reality, either due to the complexity of the scaling laws or to economize experimental cost and time, it may not be feasible to construct the model to fulfil the scaling laws completely. Thus, several possible models of partial similitude are investigated numerically. These include models with distortion in laminated material properties, stacking sequences and number of plies. Model with distortion in material properties yields a high percentage of discrepancy and is not recommended.
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Dietrich, Pierre, Fulvio Franchi, Larona Setlhabi, Rose Prevec, and Marion Bamford. "The nonglacial diamictite of Toutswemogala Hill (lower Karoo Supergroup, central Botswana): Implications on the extent of the late Paleozoic ice age in the Kalahari–Karoo Basin." Journal of Sedimentary Research 89, no. 10 (October 8, 2019): 875–89. http://dx.doi.org/10.2110/jsr.2019.48.
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ABSTRACT Along the easternmost edge of the Karoo–Kalahari Basin (KKB) of Botswana, the Toutswemogala Hill succession exposes a 30–50-m-thick suite of siliciclastic deposits interpreted by some as glaciogenic in origin tied to the Permo-Carboniferous Late Paleozoic Ice Age (LPIA). Six facies associations (FA) were recognized in this succession, resting unconformably on a highly uneven Archean gneissic basement, and consisting from base to top of: 1) clast-supported breccia made up of angular cobbles and boulders ubiquitously derived from the underlying basement, 2) well-bedded siltstones sealing or locally interdigitated with the underlying breccia, and bearing abundant remnants of Glossopteris sp. leaves, 3) a chaotic to faintly laminated matrix-supported diamictite bearing angular and subrounded clasts and tree logs attributed to the genus Megaporoxylon, 4) cross-bedded conglomerate bearing well-rounded quartz and clasts, 5) planar-laminated to ripple-laminated, poorly sorted, muddy sandstones showcasing dispersed mud chips that grade upward into 6) poorly sorted, cross-bedded coarse-grained sandstones displaying convolute beds and abundant imprints of unidentifiable tree logs. No evidence of glaciogenic processes have been found in this succession, in the form of either pavement or clasts striations. The breccia and diamictite are interpreted as scree and mass-flow deposits, respectively. Along with the age of the deposits, inferred from the plant debris (upper Carboniferous to lower Permian), the stratigraphic position of this sedimentary succession resting on the Archean basement suggests that it corresponds to the Dukwi Formation, a stratigraphic equivalent of the Dwyka Group in the Main Karoo Basin. This would explain the resemblance of the facies to those recovered at the base of the central Kalahari–Karoo Basin and in the neighboring Tuli, Ellisras, and Tshipise basins. The absence of diagnostic criteria for glacial processes in the studied succession raises the question of the extent, in both time and space, of the LPIA-related ice masses over southern Africa and particularly in southeastern Botswana. It is suggested here that during this glacial epoch, spatially restricted ice masses were confined in bedrock valleys (valley glaciers) in an uplifted setting otherwise characterized by non-glaciogenic processes, further strengthening the scenario of fragmented ice masses over southern Gondwana.
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Hien, Ta Thi, Tran Ich Thinh, and Nguyen Manh Cuong. "Numerical analysis of free vibration of cross-ply thick laminated composite cylindrical shells by continuous element method." Vietnam Journal of Mechanics 35, no. 1 (April 10, 2013): 17–30. http://dx.doi.org/10.15625/0866-7136/35/1/2891.
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This paper presents the vibration analysis of thick laminated composite cylindrical shells by a new approach using the Continuous Element Method (CEM). Based on the analytical solutions for the differential equations of thick composite cylindrical shell taking into account shear deflection effects, the dynamic transfer matrix is built from which natural frequencies are easily calculated. A computer program is developed for performing numerical calculations and results from specific cases are presented. Numerical results of this work are compared with published analytical and Finite Element Method (FEM) results. Through different examples, advantages of CEM are confirmed: reduced size of model, higher precision, reduced time of computation and larger range of studied frequencies.
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Yi, Sung, and H. H. Hilton. "Free Edge Stresses in Elastic and Viscoelastic Composites Under Uniaxial Extension, Bending, and Twisting Loadings." Journal of Engineering Materials and Technology 119, no. 3 (July 1, 1997): 266–72. http://dx.doi.org/10.1115/1.2812255.
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Time-dependent interlaminar stresses in elastic and viscoelastic laminated composites subjected to arbitrary combinations of axial extension, bending and/or twisting loads are obtained based on integral constitutive relations and Pipes and Pagano’s displacement field for laminates under a generalized plane deformation state. Numerical results obtained from the present formulation are compared against experimental data and excellent agreement within two percent was obtained between these results. Time-dependent interlaminar stresses for cross-ply and angle-ply laminates subjected to uniaxial extension, bending and twisting are also presented. Appreciable stress relaxation occurred during the loading period resulting in decreased magnitudes of residual stresses. It is seen that the rate of interlaminar shear stress relaxation is greater than the normal one, since the relaxation of shear moduli is larger than that of the normal moduli.
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Contiguglia, Carlotta Pia, Angelo Pelle, Zhichao Lai, Bruno Briseghella, and Camillo Nuti. "Chinese High Rise Reinforced Concrete Building Retrofitted with CLT Panels." Sustainability 13, no. 17 (August 27, 2021): 9667. http://dx.doi.org/10.3390/su13179667.
Full textAbstract:
Cross laminated timber (CLT) panels have been gaining increasing attention in the construction field as a diaphragm in mid- to high-rise building projects. Moreover, in the last few years, due to their seismic performances, low environmental impact, ease of construction, etc., many research studies have been conducted about their use as infill walls in hybrid construction solutions. With more than a half of the megacities in the world located in seismic regions, there is an urgent need of new retrofitting methods that can improve the seismic behavior of the buildings, upgrading, at the same time, the architectural aspects while minimizing the environmental impact and costs associated with the common retrofit solutions. In this work, the seismic, energetic, and architectural rehabilitation of tall reinforced concrete (RC) buildings using CLT panels are investigated. An existing 110 m tall RC frame building located in Huizhou (China) was chosen as a case study. The first objective was to investigate the performances of the building through the non-linear static analysis (push-over analysis) used to define structural weaknesses with respect to earthquake actions. The architectural solution proposed for the building is the result of the combination between structural and architectonic needs: internal spaces and existing facades were re-designed in order to improve not only the seismic performances but also energy efficiency, quality of the air, natural lighting, etc. A full explanation of the FEM modeling of the cross laminated timber panels is reported in the following. Non-linear FEM models of connections and different wall configurations were validated through a comparison with available lab tests, and finally, a real application on the existing 3D building was discussed.