Artigos de revistas: "Analysis of moment structures"

1

Arbuckle, James L. "AMOS: Analysis of Moment Structures". American Statistician 43, n.º 1 (fevereiro de 1989): 66. http://dx.doi.org/10.2307/2685178.

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2

Thanh Quang, Nguyen, e Nguyen Thuy Tien. "Enhancing structural health monitoring of bridge beams through spectral moment analysis". Transport and Communications Science Journal 74, n.º 4 (15 de maio de 2023): 400–412. http://dx.doi.org/10.47869/tcsj.74.4.2.

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Investigating the occurrence of defects in structures is currently a major issue of significant interest. In this paper, we present experimental research findings on the relationship between the moments of the power spectrum and the presence of damage in bridge beam structures. The study is based on analysing the random oscillation signal of the structure under the effect of random displacement loads. The results demonstrate that the value of the spectral moment is a sensitive feature to abnormal changes inside the structure. As a result, the output obtained from our study suggests using the spectral moment parameter as a new characteristic quantity for monitoring changes in bridge structures. Compared to traditional quantities like deflection, natural frequency, and mode shape, the value of the spectral moment can be more accurately determined. In the future, the spectral moment value can be extended to evaluate different types of structures under complex load conditions.

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E, Shiyuan, Yanzhong Wang, Bin Xie e Fengxia Lu. "An Adaptive Kriging-Based Fourth-Moment Reliability Analysis Method for Engineering Structures". Applied Sciences 14, n.º 8 (12 de abril de 2024): 3247. http://dx.doi.org/10.3390/app14083247.

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The fourth-moment method can accurately perform a reliability analysis when it is challenging to determine the distribution of the random variable due to limited available samples. This method only utilizes the first four moments of the random variable and constructs the fourth-moment reliability index. However, it cannot be applied in engineering cases where the state function cannot be expressed explicitly, as it becomes difficult to establish a correlation between the first four moments of the random variable and the state function. Simplifying the state function forcefully may result in significant reliability prediction errors. To address this limitation, this study proposes an adaptive Kriging-based fourth-moment method for reliability analysis under complex state equations. The proposed method demonstrates better applicability and efficiency compared to existing methods. Several numerical examples are provided to validate the effectiveness and accuracy of the proposed method.

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4

Arbuckle, James L. "Computer announcement amos: Analysis of moment structures". Psychometrika 59, n.º 1 (março de 1994): 135–37. http://dx.doi.org/10.1007/bf02294272.

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Kou, Su Xia, e Nan Guo. "Analysis Method of Secondary Moment in Prestressed Plane Structures". Applied Mechanics and Materials 105-107 (setembro de 2011): 953–56. http://dx.doi.org/10.4028/www.scientific.net/amm.105-107.953.

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In prestressed plane structures, tensioning prestressing tendons in one direction will bring primary moment in another direction, so the method of calculating secondary moment by removing the primary moment from the resultant moment is not applicable for plane structures, in which the primary moment is calculated by prestressing force multiplying the distance from prestressing force to neutral axis of section. The reason for this method can not be used for calculating secondary moment in plane structures is analyzed. The method for calculating secondary moment in plane structures is presented.

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6

Bondy, K. Dirk. "A More Rational Approach to Capacity Design of Seismic Moment Frame Columns". Earthquake Spectra 12, n.º 3 (agosto de 1996): 395–406. http://dx.doi.org/10.1193/1.1585890.

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Inelastic time history analyses typically indicate that the traditional sub-assembly “capacity” approach used in the design of ductile moment frames grossly underestimates the maximum moments experienced by the columns during a maximum credible earthquake. In addition, these analyses predict that the maximum column demand moments often occur near the mid-height of concrete structures, whereas a conventional elastic analysis predicts maxima at the lowest levels of these structures. Incremental displacement analyses using modal properties and displacements predicted by a maximum credible response spectrum should be used to more accurately predict the maximum anticipated column demand moments in the analysis of existing structures or the design of new structures.

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7

A. Badir e M. Badir. "Column Analogy in Multi-Cell Structures with Fixed Columns". Electronic Journal of Structural Engineering 12 (1 de janeiro de 2012): 95–107. http://dx.doi.org/10.56748/ejse.12156.

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A procedure is presented for the analysis of multi-cell structures such as multi-span and mul-ti-storey frames by use of the method of column analogy, normally applicable to analysis of single-span and closed frames. The multi-cell structure is first divided into a number of cells each of which can be readily ana-lyzed by column analogy for the applied external loads. A number of simultaneous equations are then written to restore continuity of the isolated cells. Certain moment-coefficients are computed also by column analogy, and used in writing the continuity equations. Solution of these equations yields moment corrections which are superimposed to the moments of the isolated cells to arrive at the final bending moments of the multi-cell structure. The procedure is presented for the analysis of frames with fixed columns, and is applied for the analysis of three examples in order to illustrate the details of the solution. Results obtained are in excellent agreement with values calculated using the stiffness method.

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Cernescu, Anghel, Jani Romanoff e Heikki Remes. "The Effect of the Secondary Bending Moment on the Fracture Strength Evaluation of the Laser Welded Joints from a Web Core Sandwich Structure". Key Engineering Materials 601 (março de 2014): 124–28. http://dx.doi.org/10.4028/www.scientific.net/kem.601.124.

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During the last period the interest on the sandwich structures has became more favorable due to the strength to weight ratio. In the same manner, in ship building field the lightweight structures became more and more attractive. With increasing the usage fields has increased the need to study the behavior of these structures. In general all the sandwich structures loaded in bending shows an effect of the secondary bending moment. In the case of web core sandwich panels used in ship structures has been observed a pronounced effect of the secondary bending moment on laser welded joints. Considering this, the paper presents an analysis of the fracture strength of laser welded joints of a web core sandwich structure, due to the effect of secondary bending moment. In the first part, the paper analytical formulation of the secondary bending moments and their effect on welded joints. This effect is explained on the basis of angle α defined in the paper and which depends on the thickness of the face plate, the thickness of the web plate and respectively the height. The paper continues with a numerical analysis of the stress and strain state from a web core sandwich beam and where also it is analyzed the effect of the secondary bending moment on the fracture strength of laser welded joints. Based on the carried out study it was observed that for high thickness of the web plate the effect of secondary bending moments is the overloading of the welded joints, instead for small thickness of the web plate the effect of the secondary bending moments can be of the unloading the welded joints. However, a small thickness of the web plate can affect the rigidity of the structure. Therefore, based on this study was proposed a solution to reduce the secondary bending moment without reducing the stiffness of the sandwich panel. The analysis conducted in this paper can be a design criterion for the web core sandwich structures.

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9

Choi, Dong-Ho, Gi-Nam Kim e Peter M. Byrne. "Evaluation of moment equation in the 2000 Canadian highway bridge design code for soil–metal arch structures". Canadian Journal of Civil Engineering 31, n.º 2 (1 de fevereiro de 2004): 281–91. http://dx.doi.org/10.1139/l03-097.

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This paper evaluates the moment equation in the 2000 Canadian highway bridge design code (CHBDC) for soil–metal arch structures. This equation is adopted from Duncan's moment equation (1978), which is based on his finding from finite element analyses that the maximum moment occurs at the quarter point of soil-metal structures. However, finite element analyses carried out for this study demonstrate that the maximum moment in soil–metal arch structures with spans greater than approximately 11 m occurs at the crown point. In this study, the location and magnitude of the maximum moment was examined for soil–metal arch structures having spans of 6–20 m under three construction stages; backfill up to the crown, backfill up to the cover depth, and live loading. Based on the location of the maximum moment, two sets of moment equations dependant on span length were found necessary. Moment coefficients and moment reduction factors in moment equations are proposed from the results of numerous finite element analyses for semi-circular arch and part-arch types of soil–metal structures considering the various design variables, such as span length, structural shapes, section properties, and backfill conditions. The validity of the coefficients and reduction factors in the moment equation of the 2000 CHBDC is investigated by comparison with those proposed in this study. The comparison demonstrates that the moment equation of the 2000 CHBDC is still valid and a little conservative. The effects of design variables on the variations of moments of soil–metal arch structures during construction stages are also examined.Key words: soil–metal arch structures, moment equations, CHBDC, soil-structure interaction.

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10

Dickinson, Robert R., e Gordon J. Savage. "Automated second moment analysis of large structures with random excitations". Computers & Structures 27, n.º 5 (1987): 657–69. http://dx.doi.org/10.1016/0045-7949(87)90082-4.

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Li, Chun, Feng Ying e Hua Zhao. "Finite Element Analysis of Sealing Structures for SF6 Gas Insulated Switchgear". Advanced Materials Research 690-693 (maio de 2013): 2738–41. http://dx.doi.org/10.4028/www.scientific.net/amr.690-693.2738.

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The sealing equipment of the SF6 GIS including the rubber O-ring and bolts were numerically simulated. Effects of bolts number, the tension moment of bolts, and gas pressure on contact stress and peak stress of O-ring were mainly studied. Simulated results showed that the bolts number and tension moment of bolts has a great effect on the sealing performance of mechanical seal and the maximum stress of O-ring. The higher contact pressure could be achieved under the condition of a larger bolts tension moment and bolts number and smaller gas pressure, but it also results in a reduce of life of O-ring.

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12

Byrne, Peter M., D. L. Anderson e Hendra Jitno. "Seismic Analysis of Large Buried Culvert Structures". Transportation Research Record: Journal of the Transportation Research Board 1541, n.º 1 (janeiro de 1996): 133–39. http://dx.doi.org/10.1177/0361198196154100117.

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Field experience indicates that large buried culverts have suffered essentially no damage during past earthquakes when no significant permanent ground movements have occurred. These soil structures, which generally comprise steel or concrete arch members and engineered soil, may have spans of 15 m. Static, pseudodynamic, and dynamic finite-element analyses have been carried out on these structures and indicate that for horizontal seismic loading, the surrounding soil is much stiffer than the arch and results in the seismic load being taken by the soil rather than by the arch. Under vertical seismic loading, the arch is stiffer than the surrounding soil and attracts significant load, which can essentially be accounted for by increasing the unit weight of the soil in proportion to the vertical acceleration. Thrusts and moments in a 10-m concrete arch are examined under combined static and seismic loading (both horizontal and vertical). The results indicate that significant increases in thrust and moment in the arch are predicted for peak ground accelerations in excess of 0.3 g. The good behavior of these structures under such acceleration levels in California, where they are not specifically designed for earthquake forces, indicates that their static design includes sufficient reserve to prevent failure under accelerations of these levels.

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13

Sudarsana, Ketut, Wiryadi Gegiranang e Susila Adi. "Finite element analysis of punching shear-unbalanced moment interactions at edge column-flat plate connections". Journal of Applied Engineering Science 20, n.º 1 (2022): 91–100. http://dx.doi.org/10.5937/jaes0-31703.

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The unbalance moments at the edge connections of flat plate structures induced by lateral forces (i.e. an earthquake) may not always act in parallel directions of the building axes. Most research studied the unbalanced moments in one direction, a few of them in biaxial directions, and none of them in incline directions. This paper presents the results of a nonlinear finite element analysis on punching shear capacity at edge column-slab connections subjected to three directions of the unbalanced moments namely perpendicular, incline 45°, and parallel to the slab free edge in combination with the shear force. A 3-D numerical analysis of ten isolated edge column-plate connections was conducted by applying an appropriate element size, mesh, and calibrated material parameters of the concrete damage plasticity (CDP) model in ABAQUS. the connections were subjected to ten variations of the moment to shear (M/V) ratios. The results show that the punching shear capacity decreases exponentially for the unbalanced moment acting perpendicular and parallel to the slab free edge, and linearly for unbalanced moment incline 45° as the increase in M/V ratio. The M-V interaction at the edge connections depends on the unbalanced moment directions which are slightly different from the ACI 318 code.

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14

Shin, Yung S., Booki Kim e Alexander J. Fyfe. "Stress Combination for Fatigue Analysis of Ship Structures". Journal of Offshore Mechanics and Arctic Engineering 127, n.º 2 (22 de dezembro de 2004): 175–81. http://dx.doi.org/10.1115/1.1924399.

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A methodology for calculating the correlation factors to combine the long-term dynamic stress components of ship structure from various loads in seas is presented. The proposed methodology is valid for a stationary ergodic narrow-banded Gaussian process. The total combined stress in short-term sea states is expressed by linear summation of the component stresses with the corresponding combination factors. This expression is proven to be mathematically exact when applied to a single random sea. The long-term total stress is similarly expressed by linear summation of component stresses with appropriate combination factors. The stress components considered here are due to wave-induced vertical bending moment, wave-induced horizontal bending moment, external wave pressure, and internal tank pressure. For application, the stress combination factors are calculated for longitudinal stiffeners in midship cargo and ballast tanks of a crude oil tanker. It is found that the combination factors strongly depend on wave heading and period in the short-term sea states. It is also found that the combination factors are not sensitive to the selected probability of exceedance level of the stress in the long-term sense.

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15

Khajehpour, Mehdi, Yuxin Pan e Thomas Tannert. "Seismic Analysis of Hybrid Steel Moment Frame CLT Shear Walls Structures". Journal of Performance of Constructed Facilities 35, n.º 5 (outubro de 2021): 04021059. http://dx.doi.org/10.1061/(asce)cf.1943-5509.0001633.

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16

Chang, L., X. G. Ye, D. C. Wang e K. N. Li. "Seismic Energy Response Analysis of Reinforced Concrete Moment Resisting Frame Structures". Advanced Science Letters 4, n.º 8 (1 de agosto de 2011): 2897–901. http://dx.doi.org/10.1166/asl.2011.1744.

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17

Behnam, Behrouz. "Failure Sensitivity Analysis of Tall Moment-Resisting Structures Under Natural Fires". International Journal of Civil Engineering 16, n.º 12 (5 de julho de 2017): 1771–80. http://dx.doi.org/10.1007/s40999-017-0248-x.

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18

Barroso, Luciana R., e Steven Winterstein. "Probabilistic seismic demand analysis of controlled steel moment-resisting frame structures". Earthquake Engineering & Structural Dynamics 31, n.º 12 (2002): 2049–66. http://dx.doi.org/10.1002/eqe.201.

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Yang, Yang, Fan Wang e Jieshan Liu. "Application of Honeycomb Structures in Key Components of Space Deployable Structures". Advances in Materials Science and Engineering 2022 (8 de novembro de 2022): 1–12. http://dx.doi.org/10.1155/2022/4756272.

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The reed structure is the key component in the foldable space deployment mechanism. In the aerospace industry, weight loss occupies a pivotal position. The use of lightweight structure can achieve significant savings in launch costs and improve load efficiency. Aiming at the lightweight requirements of the space deployment mechanism, this paper discusses the substitution effect of the honeycomb topology on the reed structure in the space deployment structure. Firstly, the column structure of the honeycomb is equivalent to an orthotropic cylindrical block-shell structure. According to the bending theory of an orthotropic cylinder, the expanded honeycomb structure equivalent to an orthotropic cylindrical block-shell structure is deduced. Then, the exact expression of the reverse bending moment was obtained, and the bending moment-curvature curve during the folding process was drawn. The bending moment-curvature characteristics during the folding process are simulated by finite element numerical simulation. By proposing the index of unit mass for analysis and comparison, the results show that compared with the common spring steel structure, the honeycomb structure has better mechanical properties per unit mass and has a certain substitution effect on the reed structure.

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Yang, Yang, Fan Wang e Jieshan Liu. "Analysis of the Mechanical Properties and Study of Influential Factors of Different Materials in Tape Spring". Applied Sciences 13, n.º 10 (22 de maio de 2023): 6315. http://dx.doi.org/10.3390/app13106315.

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This paper analyzes and calculates the mechanical properties of composite tape spring structures during folding and bending and establishes a non-linear control equation for the folding and bending of composite laminate tape spring structures. Accurate expressions for folding and bending displacements are obtained. The influence of the cross-section’s central angle and the composite tape spring’s ply thickness on their mechanical properties are analyzed. Finite element numerical analysis is performed on [−45 45]s laminated composite tape springs, and the correctness of the theoretical derivation is proved by comparing the curvature radius-bending moment curve. Based on previous research, the mechanical properties of different tape spring materials and structures are compared, further studying the lightweight design of space deployment mechanisms. The results show that the steady-state bending moment performance of composite tape springs is excellent, with a 162.1% improvement in steady-state bending moment performance per unit mass compared to traditional metallic tape springs. Additionally, the critical bending moment performance of negative Poisson ratio honeycomb structure tape springs is also excellent, with a 62.3% improvement in steady-state bending moment performance per unit mass compared to traditional metallic tape springs.

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Nazila, Kamila Shaomi, e Kamaludin Kamaludin. "Pembesaran Gaya Dalam dan Rasio Kekuatan Elemen Struktur Baja untuk berbagai Zona Gempa di Indonesia. (Hal. 74-84)". RekaRacana: Jurnal Teknil Sipil 5, n.º 1 (29 de março de 2019): 74. http://dx.doi.org/10.26760/rekaracana.v5i1.74.

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ABSTRAKStruktur bangunan dapat dikatakan kuat jika dapat memikul semua beban salah satunya, beban gempa. Waktu mendesain struktur akibat beban gempa lebih lama daripada akibat beban tanpa gempa. Penelitian ini bertujuan untuk memprediksi pembesaran gaya dalam dan prediksi rasio kekuatan pada struktur akibat adanya beban tanpa gempa. Penelitian ini dilakukan terhadap gedung 10 lantai dengan material baja. Tujuh model variasi beban pada gedung sebagai berikut: beban tanpa gempa,beban tanpa gempa dan percepatan 0,2 ; 0,4 ; 0,6 ; 0,8 ; 1,0 ; juga 1,2 . Analisis gaya dalam dan pengecekan kekuatan struktur bangunan menggunakan software ETABS 2015. Hasil yang diperoleh pada balok yaitu, gaya lentur ( ) dengan pembesaran momen maksimum kurang lebih 0,9 kali terhadap momen akibat beban tanpa gempa. Pembesaran momen relatif antar variasi beban kurang lebih 1,2. Hal ini mengakibatkan rasio untuk desain awal kurang lebih 30% untuk daerah gempa kuat.Kata kunci: struktur baja, beban gempa, pembesaran momen, pembesaran rasio. ABSTRACTThe structure of the building can be said to be strong if it can carry all the loads, such as the earthquake loads. Time to design structures due to earthquake loads is longer than without earthquakes loads. This study aims to predict the magnification of internal forces and the ratio of strength to structures due to without earthquake loads. This research was conducted on 10-storysteel building. Seven models of load variations in the building are as follows: load without earthquake, load without earthquake and acceleration of 0.2 , 0.4 , 0.6 , 0.8 , 1.0 , and 1.2 . The internal force analysis and checking of building structure strengthare using ETABS 2015. The results obtained that flexural force ( ) with a maximum moment magnification of approximately 0.9 times the moment due to without earthquake loads on the beam. Enlargement of relative moments between load variations is approximately 1.2. Therefore, ratio of the initial design is approximately 30% for strong earthquake areas. Keywords: steel structure, earthquake load, moment magnification, ratio enlargement.

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Leelataviwat, Sutat, Subhash C. Goel e Božidar Stojadinović. "Toward Performance-Based Seismic Design of Structures". Earthquake Spectra 15, n.º 3 (agosto de 1999): 435–61. http://dx.doi.org/10.1193/1.1586052.

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A new performance-based plastic design procedure for steel moment frames is presented in this paper. The role of plastic analysis in seismic design of structures is illustrated. The ultimate design base shear for plastic analysis is derived by using the input energy from the design pseudo-velocity spectrum, a pre-selected yield mechanism, and an ultimate target drift. The proposed design procedure eliminates the need for a drift check after the structure is designed for strength as is done in the current design practice. Also, there is no need for response modification factors since the load deformation characteristics of the structure, including ductility and post-yield behavior, are explicitly used in calculating the design forces. The results of nonlinear static and nonlinear dynamic analyses of an example steel moment frame designed by the proposed method are presented and discussed. The implications of the new design procedure for future generation of seismic design codes are also discussed.

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Robinson Wolf, Zane, Beth M. King e Nancey E. M. France. "Antecedent Context and Structure of Communication During a Caring Moment: Scoping Review and Analysis". International Journal of Human Caring 19, n.º 2 (março de 2015): 7–21. http://dx.doi.org/10.20467/1091-5710.19.2.7.

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This scoping review and analysis of related literature induced the structure of the nurse-patient communication process during a caring moment. Data sources consisted of literature from databases, using the search terms of caring encounter, caring moment, nurse, nursing, patient, patient-centered care, relationship, and communication, and related theories and personal collections of investigators. Using thematic analysis, investigators reviewed citations for units of text with similar meanings indicating structures of a caring moment. Data synthesis produced the structure of the caring moment presented as a narrative. Results provide nursing faculty an opportunity to examine core elements of the caring moment with students.

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Afshari, Mohammad Jalilzadeh, Ali Kheyroddin e Majid Gholhaki. "Simplified Time-Dependent Column Shortening Analysis in Special Reinforced Concrete Moment Frames". Periodica Polytechnica Civil Engineering 62, n.º 1 (25 de setembro de 2017): 232–49. http://dx.doi.org/10.3311/ppci.10679.

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Necessity for adaption of high-rise reinforced concrete structures’ design and practical steps of implementation through nonlinear staged analysis by consideration of long-term behavior of concrete have always been strongly recommended by researchers in recent years. Cumulative column shortening in conventional analyses is the most important consequence of neglecting the above issues. In this article, numerous modeling and extensive nonlinear staged analyses are carried out on structures with different geometrical characteristics and extremely simple empirical equations to estimate column shortening caused by creep, shrinkage and time changes of modulus of elasticity are provided in such a way that these relations can be independent of conventional parameters of ACI209R-92 regulations used in prediction of mentioned axial strains. Results obtained from validation of the proposed equations show high compliance of all proposed equations for up to 30 floors and also show accuracy of proposed shrinkage equation for the moment frame structures higher than the studied range.

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Bunger, R., e F. Arndt. "Moment-method analysis of arbitrary 3-D metallic N-port waveguide structures". IEEE Transactions on Microwave Theory and Techniques 48, n.º 4 (abril de 2000): 531–37. http://dx.doi.org/10.1109/22.842024.

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Alhassan, Mahmoud, e Mohamad Abdelrahim. "Plastic hinge assessment of RC moment-resisting frames". International Journal of Advanced Engineering, Sciences and Applications 1, n.º 3 (15 de julho de 2020): 37–41. http://dx.doi.org/10.47346/ijaesa.v1i3.29.

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This paper gives a short introduction about various kinds of analysis, plastic hinges, moment-resisting frames (MRFs) in RC Structures. It likewise gives computer software ETABS displaying and an investigation of structures concerning Pushover Analysis. The fundamental reason for this examination is to apply a push to all models, analyse and get a reasonable thought regarding their behaviour. The behaviour of these structures likewise was evaluated considering various variables such as the changes in the number of floors, spans length, reinforcements' yield strength and characteristic strength of concrete. This investigation incorporates the moment-resisting frames (MRFs) having 4, 7, and 10 storeys and a relative report for all models' outcomes. Pushover analysis is a nonlinear static analysis used to determine the relationship between strength and displacement in order to evaluate the performance of the RC frame structure. It was found that the plastic hinge may be assessed using parameters such as span lengths and the number of storeys. When the number of storeys increases, the elastic stiffness value decreases and when the span length increases the elastic stiffness also decreases. The collapse of members happens only when there is a formation of 3 hinge mechanisms. Plastic hinge colours have been given, and each colour has its significance to permit a good design.

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Zeng, Jian Yu, e Xiao Zu Su. "Internal Force System and Current Secondary Moment Concept in Prestressed Structures". Applied Mechanics and Materials 501-504 (janeiro de 2014): 611–19. http://dx.doi.org/10.4028/www.scientific.net/amm.501-504.611.

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The internal forces in a prestressed concrete structure are of special nature due to the existence of tendons. And flaws can be found in the traditional concept of secondary moment such that common computation method of secondary moment may produce unreasonable results. This article aims at getting a better understanding of internal forces in prestressed structures and solving the relevant problems. Starting from the basic principles of internal force analysis, a new system of internal forces is put forward by which the relationship between the compression resultant on concrete cross-section and the sectional internal forces is made clear. On this basis, a definition on the concept of current secondary moment (Mcs) is proposed and its superiority pointed out. Finally, theoretical analyses are carried out on the method for calculating Mcs in the posttentioned continuous beams with unbonded and bonded prestressing tendons.

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Belegundu, A. D. "Probabilistic Optimal Design Using Second Moment Criteria". Journal of Mechanisms, Transmissions, and Automation in Design 110, n.º 3 (1 de setembro de 1988): 324–29. http://dx.doi.org/10.1115/1.3267465.

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Probability-based optimal design of structures is presented. The emphasis here is to develop a practical approach to optimal design given random design parameters. The method is applicable to structures which are modeled using the finite element method. The Hasofer-Lind (H-L) second-moment design criterion is used to formulate the general design problem. A method for calculating the sensitivity coefficients is presented, which involves second-order design sensitivity analysis. The importance of second order derivatives is established. A nonlinear programming technique is used to solve the problem. Numerical results are presented, where stiffness parameters are treated as random variables.

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Rosowsky, David V. "Evolution of probabilistic analysis of timber structures from second-moment reliability methods to fragility analysis". Structural Safety 41 (março de 2013): 57–63. http://dx.doi.org/10.1016/j.strusafe.2012.10.004.

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Wieser, Joseph, Gokhan Pekcan, Arash E. Zaghi, Ahmad Itani e Manos Maragakis. "Floor Accelerations in Yielding Special Moment Resisting Frame Structures". Earthquake Spectra 29, n.º 3 (agosto de 2013): 987–1002. http://dx.doi.org/10.1193/1.4000167.

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Severe damage to acceleration sensitive nonstructural components in recent earthquakes has resulted in unprecedented losses. Recent research has been aimed at increasing the understanding of acceleration demands on nonstructural components in buildings. This investigation subjects a set of four special moment resisting frame (SMRF) building models to a suite of 21 far-field ground motions using the incremental dynamic analysis procedure. Full three-dimensional models including floor slabs are used to extract both the horizontal and vertical responses. Floor acceleration response spectra are generated to assess the acceleration demands on elastic nonstructural components. Changes to the current code provisions that include the influence of structural period are proposed. An alternative design approach that directly amplifies the ground acceleration spectrum to achieve the desired floor acceleration spectrum is presented.

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Shakshuki, Elhadi, Kumaraswamy Ponnambalam e Tassew Wodaj. "Risk analysis in environmental systems". Canadian Journal of Civil Engineering 29, n.º 1 (1 de fevereiro de 2002): 1–7. http://dx.doi.org/10.1139/l01-072.

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Uncertainty is an inherent feature of environmental systems, which makes probabilistic models important. Environmental risk assessment is an important but time consuming task. For large-scale systems, use of linear systems with uncertainty information on parameters and inputs is one of the few possible methods to assess risk. To estimate risk, it is necessary to have at least the first two moments of output variables. This paper describes an efficient method developed for second-moment analysis of linear systems with uncertain coefficients. The main objective is to provide the means and the variances of the output and to provide efficient formulation and automation of the moment equations. This method is demonstrated in two real-world applications of environmental modeling.Key words: uncertainty, second-moment methods, risk analysis, reliability, linear systems.

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Agbonaye, Augustine Iyekeoretin, Ebierin Akpoebidimiyen Otuaro e Osadolor Christopher Izinyon. "COMPARISON OF L-MOMENT AND METHOD OF MOMENTS AS PARAMETER ESTIMATORS FOR IDENTIFICATION AND CHOICE OF THE MOST APPROPRIATE RAINFALL DISTRIBUTION MODELS FOR DESIGN OF HYDRAULIC STRUCTURES". Journal of Civil Engineering, Science and Technology 13, n.º 1 (22 de abril de 2022): 33–48. http://dx.doi.org/10.33736/jcest.4207.2022.

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In rainfall frequency analysis, the choice of a suitable probability distribution and parameter estimation method is critical in forecasting design rainfall values for varying return periods at every location. Previously, some researchers in Nigeria used the method of moments (MoM) while others used the L-moment method (LMM) as parameter estimators. However, a more accurate result is obtainable if both estimators are used and their results are compared and ranked to obtain the most appropriate distribution models for each location This study compared the performance of two forms of parameter estimation, namely the method of moments (MoM) and the L-moment method (LMM). This was aimed at identifying and selecting the best fit probability distribution models among three distribution models for the design of hydraulic structures. These models are Generalized Pareto (GPA), Generalized Extreme Value (GEV), and Gumbel Extreme Value (EVI). Annual rainfall series of ten gauging stations with data from 33-50 years from ten southern States of Nigeria obtained from NIMET were used for Rainfall Frequency Analysis (RFA). At five locations, the best fit probability model was the GPA probability distribution model with L-Moment. EVI and GEV probability distribution models with the method of moments were the most appropriate probability models at two locations each. EVI probability distribution model with the L-moment was the most appropriate probability model at one place. The findings confirmed that no single distribution outperformed all others at all stations. Since no single model is regarded preferable for all practical purposes, the best-fit probability model with parameter estimator at any location is site-specific. Consequently, available models and parameter estimators are filtered based on the situation at hand and the type of data available. The identified best fit models with the most appropriate parameter estimator would be a tool to help decision-makers in sizing hydraulic structures in the area.

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Jawad, Faris Waleed. "Finite Element Analysis of Raft Foundation under Coupled Moment". Journal of Engineering 24, n.º 10 (1 de outubro de 2018): 73. http://dx.doi.org/10.31026/j.eng.2018.10.06.

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Due to wind wave actions, ships impacts, high-speed vehicles and others resources of loading, structures such as high buildings rise bridge and electric transmission towers undergo significant coupled moment loads. In this study, the effect of increasing the value of coupled moment and increasing the rigidity of raft footing on the horizontal deflection by using 3-D finite element using ABAQUS program. The results showed that the increasing the coupled moment value leads to an increase in lateral deflection and increase in the rotational angle (α◦). The rotational angle increases from (0.014, 0.15 to 0.19) at coupled moment (120 kN.m), (0.29, 0.31 and 0.49) at coupled moment (240 kN.m) and (0.57, 0.63 and 1.03) at coupled moment (480 kN.m) with decreasing the raft thickness from (1.5, 1.0 to 0.5m), respectively. The computed maximum lateral deflection decreases with increasing the rigidity of raft. The maximum deflection decreases from (40 to 3mm) at coupled moment 120 kN.m, (150 to 60mm) at coupled moment 240 kN.m and (210 to 118mm) at coupled moment 480 kN.m with increase raft thickness from (t = 0.5 to 1.5m) and the maximum reduction in maximum stress value and lateral deflection mobilized due to applied coupled moment is noticed when width to thickness of footing ratio is less than (w/t<12). The failure of the footing is noticed when the rotational angle is more than 4◦ (α > 4◦)

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Bakht, Baidar, e Leslie G. Jaeger. "Dealing with varying moments of inertia of girders in bridge analysis". Canadian Journal of Civil Engineering 15, n.º 2 (1 de abril de 1988): 232–39. http://dx.doi.org/10.1139/l88-031.

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In many slab-on-girder bridges, especially those that are continuous over two or more spans, the moment of inertia of a girder varies significantly along the length of the bridge. This paper critically examines the practice of analyzing such bridges for load distribution by methods that make the assumption of constant longitudinal torsional and flexural rigidities. It is found that this practice may not be valid for those slab-on-girder bridges in which variations of the girder moments of inertia are very large.A recommended procedure is given for cases in which the variation in moment of inertia is not too severe. The procedure involves (a) the determination of total bending moments, treating the bridge as a beam of variable moment of inertia, and (b) the determination of an equivalent constant moment of inertia for beams of varying moment of inertia. Using this procedure the load distribution properties of the bridge can be realistically analyzed by those computer-based methods (e.g., orthotropic plate, finite strip, and semicontinuum methods) or manual methods (e.g., AASHTO and Ontario methods) that cannot directly take account of the variation of longitudinal flexural rigidity.The validity of the recommended procedure is established by comparing its results with those of the grillage analysis method that does take account of the variation of the girder moment of inertia. Key words: bridge analysis, girders, load distribution, slab-on-girder bridges.

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White, Gregory J., e Bilal M. Ayyub. "Reliability-Based Design Format for Marine Structures". Journal of Ship Research 31, n.º 01 (1 de março de 1987): 60–69. http://dx.doi.org/10.5957/jsr.1987.31.1.60.

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Recently there has been increased effort by classification societies and design authorities to bring reliability analysis into the design process. Typically these efforts involve using some reliability analysis method to calculate "partial safety factors" for design equations. The mean-value first-order second-moment method (MVFOSM), the advanced second-moment method (ASM), and an "exact" method have been used, or are being proposed for use, in the design of marine structures. In some recent work it has been shown that design formats based on the first two methods may result in engineering designs of different reliability levels than the ones specified in developing the design formats. These three methods are evaluated and a "reliability-conditioned (RC) method" is proposed in this paper. The proposed method overcomes the shortcomings of the MVFOSM and ASM methods and extends the concepts of the "exact" method in a more useful form to handle general types of problems. The RC method is believed to result in partial safety factors which give engineering designs of reliability levels equal to the specified ones.

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Belostotskiy, Alexander M., Pavel A. Akimov e Dmitry S. Dmitriev. "About Contemporary Seismic Analysis of Underground Structures". Materials Science Forum 931 (setembro de 2018): 91–99. http://dx.doi.org/10.4028/www.scientific.net/msf.931.91.

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This paper is devoted to actual problems of seismic analysis of underground structures. Brief classification and overview of corresponding methods of analysis (force-based methods, displacement-based methods, numerical methods of seismic analysis of coupled system “soil – underground structure” and approaches to problems of soil-structure interaction) is presented. Special static finite element method with substructure technique for seismic analysis of underground structures is described. Dynamic soil-structure interaction system can be decomposed into three sub-structures: structure, near-field and far-field soil. The first stage of static finite element method is solving the free field shear stress, acceleration, velocity and displacement, when the moment that the relative displacement of the soil that the underground structure located in reaches the maximum. The second stage is computing of internal forces and parameters of boundary conditions. The third stage is construction of the static finite element model and imposing the loads and constrains computed at the second stage and then making a static analysis.

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Buchanan, T. S., S. L. Delp e J. A. Solbeck. "Muscular Resistance to Varus and Valgus Loads at the Elbow". Journal of Biomechanical Engineering 120, n.º 5 (1 de outubro de 1998): 634–39. http://dx.doi.org/10.1115/1.2834755.

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Although the contributions of passive structures to stability of the elbow have been well documented, the role of active muscular resistance of varus and valgus loads at the elbow remains unclear. We hypothesized that muscles: (1) can produce substantial varus and valgus moments about the elbow, and (2) are activated in response to sustained varus and valgus loading of the elbow. To test the first hypothesis, we developed a detailed musculoskeletal model to estimate the varus and valgus moment-generating capacity of the muscles about the elbow. To test the second hypothesis, we measured EMGs from 11 muscles in four subjects during a series of isometric tasks that included flexion, extension, varus, and valgus moments about the elbow. The EMG recordings were used as inputs to the elbow model to estimate the contributions of individual muscles to flexion-extension and varus-valgus moments. Analysis of the model revealed that nearly all of the muscles that cross the elbow are capable of producing varus or valgus moments; the capacity of the muscles to produce varus moment (34 Nm) and valgus moment (35 Nm) is roughly half of the maximum flexion moment (70 Nm). Analysis of the measured EMGs showed that the anconeus was the most significant contributor to valgus moments and the pronator teres was the largest contributor to varus moments. Although our results show that muscles were activated in response to static varus and valgus loads, their activations were modest and were not sufficient to balance the applied load.

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Cassiano, David, Carlos Rebelo e Luís Simoes da Silva. "Robustness Assessment of Steel Moment Resisting Frames". Open Civil Engineering Journal 11, n.º 1 (30 de junho de 2017): 420–33. http://dx.doi.org/10.2174/1874149501711010420.

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Nowadays, many buildings with steel Moment Resisting Frames (MRF) are built in seismic zones when seismic codes are at its early stages of development, and as such, these structures are often designed solely to resist lateral wind loads without providing an overall ductile mechanism. On the other hand, current seismic design criteria based on hierarchy of resistance allow enhancing the structural ductility and controlling the structural plastic behaviour. Therefore, seismic design criteria might also be beneficial to improve the structural robustness. In order to investigate this issue for steel MRF, a parametric study based on pushdown analysis and on the Energy Balance Method is described and discussed in the present paper. With this regard, the following cases are examined: (i) MRF not designed for seismic actions and (ii) MRF designed for seismic actions. The investigated parameters are (i) the number of storeys, (ii) the interstorey height, (iii) the span length, (iv) the building plan layout and (v) the column loss scenario. Results show that the low-rise and long span structures are the most prone to progressive collapse and that the elements in the directly affected zone of the wind designed 8 storey structures respond in the elastic range. Structures designed according to the capacity design principles were found to be less robust than wind designed structures that are characterized by strong beams and weak columns. The number of elements above the removed column and size of beam cross section were found to be key parameters in arresting progressive collapse.

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Valivonis, Juozas, e Tomas Skuturna. "Cracking and strength of reinforced concrete structures in flexure strengthened with carbon fibre laminates". JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 13, n.º 4 (31 de dezembro de 2007): 317–23. http://dx.doi.org/10.3846/jcem.2007.7695.

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The article presents the analysis of the cracking moment and the strength of beams reinforced with external carbon fibre. Experimental research of beams strengthened in this way has been carried out. Three different methods of anchoring external reinforcement were applied to strengthen the beams. The influence of anchorage on the cracking moment and the strength of the beams has been defined. Design methods for defining the cracking moment and the strength have been presented. The design procedure for defining the cracking moment evaluates the curvilinear stress diagrams of concrete under tension and compression. The design procedure for defining the strength of the structures evaluates the stiffness of the contact between the carbon fibre and the concrete. The design results are provided. Comparative analysis of the experimental and the theoretical results has been performed.

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Valivonis, Juozas, e Tomas Skuturna. "CRACKING AND STRENGTH OF REINFORCED CONCRETE STRUCTURES IN FLEXURE STRENGTHENED WITH CARBON FIBRE LAMINATES". JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 13, n.º 4 (31 de dezembro de 2007): 317–23. http://dx.doi.org/10.3846/13923730.2007.9636452.

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The article presents the analysis of the cracking moment and the strength of beams reinforced with external carbon fibre. Experimental research of beams strengthened in this way has been carried out. Three different methods of anchoring external reinforcement were applied to strengthen the beams. The influence of anchorage on the cracking moment and the strength of the beams has been defined. Design methods for defining the cracking moment and the strength have been presented. The design procedure for defining the cracking moment evaluates the curvilinear stress diagrams of concrete under tension and compression. The design procedure for defining the strength of the structures evaluates the stiffness of the contact between the carbon fibre and the concrete. The design results are provided. Comparative analysis of the experimental and the theoretical results has been performed.

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Chen, Chien Yuan, e Chi Xun Tsai. "Batter Pile Behavior Modeling Using Finite Difference Analysis". Applied Mechanics and Materials 566 (junho de 2014): 199–204. http://dx.doi.org/10.4028/www.scientific.net/amm.566.199.

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Pile foundation has been widely used in supporting various structures, for example, bridges and tall buildings in Taiwan. With the development of mountainous area, pile foundation has been used as mitigation slope movement. Batter piles used in a group pile subjected to lateral forces are common. In this study, we used 3D finite difference program to analyze the mechanical response of a batter pile subjected to lateral soil movement. In order to verify the correction of the numerical simulation, its validation was compared with a published case study. The analysis of a single pile in different incline angles subjected to lateral soil movement was modeled. Results of the analysis show that batter pile under the conditions of lateral soil movement will cause pile larger lateral displacement and increasing bending moment on the pile shaft. The pile displacement reduced with the increasing pile incline angle. Vertical pile shaft subjected to negative and positive moment during soil movement, while, only positive moment distributed in the batter pile shaft. The moment is higher in batter pile shaft in weak layer than in non-weak layer. The pile shaft maximum moment occurred nearby the interface of weak layer and stable layer. The moment increased with the incline angle of batter pile. While, the moment increasing ratio reduced with the increased incline angle.

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Sun, Wei, Hui Long Ren e Hui Li. "Study on the Treatment of Nonlinear Roll Damping in Hydrodynamic Calculation and Structural Analysis". Applied Mechanics and Materials 687-691 (novembro de 2014): 423–27. http://dx.doi.org/10.4028/www.scientific.net/amm.687-691.423.

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In order to insure the consistent wave loads in hydrodynamic calculation and structural analysis, the treatment of nonlinear roll damping in roll motion, wave torsional moment and structural analysis are studied. The nonlinear roll damping moment is applied to the structural model by means of the equivalent nodal forces. Taking a supply ship and a FPSO as example, the calculation results show that the problem of torsional moment distribution divergent on the bow and the unbalanced structural model is improved greatly, which would be helpful to provide the reliable basis to design the structures.

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TURKALJ, GORAN, e JOSIP BRNIĆ. "NONLINEAR STABILITY ANALYSIS OF THIN-WALLED FRAMES USING UL–ESA FORMULATION". International Journal of Structural Stability and Dynamics 04, n.º 01 (março de 2004): 45–67. http://dx.doi.org/10.1142/s0219455404001094.

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This work presents a one-dimensional finite element formulation for nonlinear analysis of spaced framed structures with thin-walled cross-sections. Within the framework of updated Lagrangian formulation, the nonlinear displacement field of thin-walled cross-sections, which accounts for restrained warping as well as the second-order displacement terms due to large rotations, the equations of equilibrium are firstly derived for a straight beam element. Due to the nonlinear displacement field, the geometric potential of semitangential moment is obtained for both the torsion and bending moments. In such a way, the joint moment equilibrium conditions of adjacent non-collinear elements are ensured. Force recovering is performed according to the external stiffness approach. Material nonlinearity is introduced for an elastic-perfectly plastic material through the plastic hinge formation at finite element ends and for this a corresponding plastic reduction matrix is determined. The interaction of element forces at the hinge and the possibility of elastic unloading are taken into account. The effectiveness of the numerical algorithm discussed is validated through the test problem.

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Noori, Mohammed S. M., e Rafaa M. Abbas. "Dynamic Response and Reliability Analysis of Stochastic Multi-Story Frame Structures under Random Excitation". Mathematical Modelling of Engineering Problems 9, n.º 5 (13 de dezembro de 2022): 1335–42. http://dx.doi.org/10.18280/mmep.090523.

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In earthquake engineering problems, uncertainty exists not only in the seismic excitations but also in the structure's parameters. This study investigates the influence of structural geometry, elastic modulus, mass density, and section dimension uncertainty on the stochastic earthquake response of a multi-story moment resisting frame subjected to random ground motion. The North-south component of the Ali Gharbi earthquake in 2012, Iraq, is selected as ground excitation. Using the power spectral density function (PSD), the two-dimensional finite element model of the moment resisting frame's base motion is modified to account for random ground motion. The probabilistic study of the moment resisting frame structure using stochastic finite element utilizing Monte Carlo simulation was presented using the finite element program ABAQUS. The dynamic reliability and probability of failure of the stochastic and deterministic structure based on the first passage failure were checked and evaluated. Results revealed that the probability of failure increased due to randomness in stiffness and mass of the structure. Generally, natural frequencies for the lower modes of vibration and relative displacements for the lower stories were more sensitive to the randomness in system parameters.

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Daryan, Amir Saedi, Soheil Palizi e Neda Farhoudi. "Optimization of plastic analysis of moment frames using modified dolphin echolocation algorithm". Advances in Structural Engineering 22, n.º 11 (24 de abril de 2019): 2504–16. http://dx.doi.org/10.1177/1369433219845151.

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The analysis of structures and, in particular, the determination of their failure mode are the basic requirements in the field of civil engineering. Obtaining this information in high-rise structures or structures with complex irregular layouts is a difficult process, which even with the use of specialized computer software is very time-consuming. In recent years, meta-heuristic algorithms have been used extensively in engineering optimization problems. This research presents an automated approach to assess plastic loads and failure modes of two-dimensional frames, in which the plastic analysis of moment frames has been optimized using the modified dolphin echolocation optimization algorithm. This method is based on the creation of the basic collapse mechanisms, which, following their combination, should reach the minimum coefficient of plastic collapse loads using virtual work theory. The efficiency of this algorithm is verified using four sample frames, which, their exact solution including minimum load factor and the corresponding critical failure mode of the structure, exit in other research. Comparison of the results shows that the proposed method provides very good results with high precision and speed and also demonstrates the failure mechanism of the structure. Meanwhile, the modifications made in this method have greatly reduced the volume of calculations. Moreover, applying changes to the dolphin echolocation optimization algorithm led to the use of this optimization algorithm for binary problems for the first time, which ultimately resulted in a good convergence rate.

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Lee, Kyung Koo, Lan Chung, Sang Hyun Lee, Tae Won Park e Jieun Rho. "Evaluation of Dynamic Collapse Behavior of Steel Moment Frames Damaged by Blast". Applied Mechanics and Materials 82 (julho de 2011): 404–9. http://dx.doi.org/10.4028/www.scientific.net/amm.82.404.

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Blast effects on structures and blast mitigation strategies have been vigorously studied in the world. The alternate path method, or common progressive collapse analysis method, of structures assumes the threat-independent removal of vertical load-carrying elements. However, in reality, a blast-induced column-missing event will produce the damage on adjacent structural elements and the rapid dynamic response of the structures. In this study, the strain rate effects on the dynamic collapse behavior of steel moment frames are investigated by performing the blast-induced sequential progressive collapse analysis. Then, the improvement of the progressive collapse analysis method is discussed based on the numerical results.

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Essid, Chaker, M. Bassem Ben Salah, Khaled Kochlef, Abdelaziz Samet e Ammar B. Kouki. "SPATIAL-SPECTRAL FORMULATION OF METHOD OF MOMENT FOR RIGOROUS ANALYSIS OF MICROSTRIP STRUCTURES". Progress In Electromagnetics Research Letters 6 (2009): 17–26. http://dx.doi.org/10.2528/pierl08112706.

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Morgunov, Mikhail V., e Anzhelika A. Lyudkevich. "Investigation of Cracking in Reinforced Concrete Structures by Means of Standardized Deformation Models". Reinforced concrete structures 3, n.º 3 (19 de julho de 2023): 20–31. http://dx.doi.org/10.22227/2949-1622.2023.3.20-31.

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In this study, a detailed analysis of the use of standardized deformation models is carried out to calculate the design characteristics of reinforced concrete elements, such as crack resistance. For theoretical verification of the values of the moment of cracking, calculation methods based on the use of a nonlinear deformation model are used.A theoretical study of cracking moment using a non-linear deformation model shows that the application of a two-line diagram of concrete deformation allows to obtain the most accurate values of cracking moment.

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Tamrazyan, Ashot G. "To the Analysis of the Reliability of Structures of Beam Systems". Reinforced concrete structures 4, n.º 4 (18 de outubro de 2023): 13–19. http://dx.doi.org/10.22227/2949-1622.2023.4.13-19.

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The article discusses the issues of reliability for various types of failures of beam systems. A single-span bending beam is analyzed. The limit state functions for moment failure modes in the characteristic sections of the beam are determined. The ways of forming a plastic hinge for a beam are shown. The lower and upper limits of the beam reliability are calculated. Limit state functions corresponding to failure mechanisms are presented.

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Saif, Khaled, Chin Long Lee, Trevor Yeow e Gregory A. MacRae. "Seismic Ratchetting of Single-Degree-of-Freedom Steel Bridge Columns". Key Engineering Materials 763 (fevereiro de 2018): 295–300. http://dx.doi.org/10.4028/www.scientific.net/kem.763.295.

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Nonlinear time history analyses of SDOF bridge columns with elasto-plastic flexural behaviour which are subject to eccentric gravity loading are conducted to quantify the effect of ratchetting. Peak and residual displacements were used as indicators of the degree of ratchetting. The effects of member axial loads and design force reduction factors were also investigated. It was shown that displacement demands increased with increasing eccentric moment. For eccentric moment of 30% of the yield moment, the average maximum and residual displacements increase by 4.2 and 3.8 times the maximum displacement, respectively, which the engineers calculate using static methods without considering ratchetting effect. Design curves for estimating the displacement demands for different eccentric moments are also developed. The current NZ1170.5 (2016) provisions were found to be inadequate in estimating the maximum displacement for steel structures, and hence, new provisions for steel structures should be presented.

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