Academic literature on the topic 'RC FRAME-WALL STRUCTURE'

The reinforced concrete (RC) frame with masonry infill wall is one of the most common structural systems in many countries. It has been widely recognized that the infill wall has significant effects on the seismic performance of RC frame structure. During the Wenchuan earthquake (China 2008), a lot of infilled RC frame structures suffered serious damages due to the detrimental effects brought about by the infill wall rigidly connected to the surrounding frame. In order to solve this problem, flexible connection, introduced by Chinese designers, is recommended by the updated Chinese seismic design code, because of its effect to reduce the unfavorable interaction between infill wall and frame. Although infilled RC frame structure with flexible connection has a lot of advantages, but because of the lack of research, this structure type is seldom used in practical engineering. Therefore, it is of great significance to scientifically investigate and analyze the effects of flexible connection on structure behaviors of infilled RC frame. In this study, a macrofinite element numerical simulation method for infilled RC frame with flexible connection was investigated. Firstly, the effects of connection between infill wall and surrounding frame on in-plane behaviors of infilled RC frame were discussed. Secondly, based on deeply studying the equivalent diagonal strut models for infilled RC frame with rigid connection, an improved equivalent diagonal strut model for infilled RC frame with flexible connection was proposed. Employed with inversion analysis theory, the parameter in the proposed model was estimated through artificial fish swarm algorithm. Finally, applied with the existing experiment results, a case study was conducted to verify the effectiveness and feasibility of the proposed model.

A new RC frame multi-ribbed composite walls structure is provided by using low yield strength steel. Two calculating structures are analyzed which one is the RC frame shear wall structure used as a comparison, and the other is the RC frame multi-ribbed composite walls structure. The nonlinear earthquake responses of the structures are calculated by using program IDARC2D.The nonlinear dynamic analysis models of the structures are established with retrogressive three-linear resilience model for beam, column and RC shear wall elements, while a smooth hysteretic model is proposed for representing low yield strength steel panels. The nonlinear dynamic time-history analysis of the structures under horizontal earthquake waves has been carried out. The earthquake responses of the structures and energy dissipation are studied, which provide more data information for the comprehension of earthquake responses and seismic performance of the RC frame multi-ribbed composite walls structure. The calculating results show that the low yield strength steel panels have obvious seismic mitigation effects, and that RC frame multi-ribbed composite walls structure has good seismic capacity.

Considering the effects of strain rate, the nonlinear dynamic response of two reinforced concrete(RC)structuresisstudied under seismic excitationsin this paper. Firstly, based on the model in a shaking table test, a three-dimensional finite element model of RC frame-shear wall structural model subjected to both horizontal and vertical component seismic excitations is established. The structural model is a three-story RC frame-shear wall structure, which consists of RC slabs, RC columns and transverse spandrel beams.Afringeframe is infilled by a RCshear wall.Then, According to the practice engineering, a multi-story RC frame structure is also established. Finally, the dynamic response of the structures is investigated using nonlinear seismic analytical method considering the effects of strain rate. These results may provide a reference for seismic design of RC structure.

The seismic damage and even collapse of the infilled walls in RC frame infilled wall structure is the issue that needs thorough study, In this paper, firstly introduces the improved infilled wall model which can consider the interaction of in-plane and out-of-plane, and can judge the damage state of infilled walls, as well as the interaction between RC frame and infilled walls. Then, based on the finite element software OpenSees, under rare earthquake, performed the nonlinear numerical simulation of two finite element models-RC frame without infilled walls and RC frame with infilled walls, comparative analysis differences of both plastic hinge zone’s steel strain, drift and acceleration response, and in-depth study of the infilled walls effect in RC frame infilled wall structure and reason analysis.

On the basis of analysis of shear wall’s simplified model—equivalent model, this article investigates its application in RC frame-shear wall structure from static elastic -plastic calculation,which carries out elastic -plastic analysis compare with wall unit and equivalent model and illuminates simplified model’s feasibility in RC frame-shear wall structure static elastic -plastic analysis under the maximum earthquake action

The infilled wall plays an important role in the formation of the survival space and life-saving passage of the seismic collapse of reinforcement concrete (RC) frame structure. Here, with the numerical modeling method of the infilled wall, the connection between infilled wall and RC frame was primarily investigated. The combined finite element (FE) and finite-discrete element (F-DE) method is proposed to simulate the multispan and multistory RC frame structure with infilled wall. The reliability of the numerical simulation method was verified by the shaking table test; the evaluation criterion includes the collapse mechanism and mode. The results show that the numerical simulation is highly consistent with the shaking table test; it is easy for RC frame structure to form short columns due to the influence of the low or half-height infilled wall, and the structural collapse is caused by the shear failure of columns; the overall structure shows pancake type of collapse; the survival space becomes smaller and smaller on the direction of structural collapse. The proposed numerical simulation method can be valuable in simulating RC frame structure with infilled wall for postearthquake rescue.

Abstract: RC frame structure is one of common used building structures. Previous studies show that infill wall significantly contribute to the seismic performance imposed on RC frame structure, increasing structural stiffness and hence leading to decrease structure's natural period. However under strong earthquake, infill wall not only holds up large lateral seismic force but also limits the deformation of beams and columns. In most of the previous studies on the behaviour of reinforce concrete building considering the effect of infill wall, rectangular shape of brick is taken into account. In this study, an attempt has been made to look over the effect of infill wall material type and its shape on the seismic performance of RC frame. This study will be restricted with single bay frame with two types of bricks a) Clay brick, b) Fly ash brick. The different shapes under consideration are rectangle and square. This study also contains the effect of size of infill wall units. The stress in concrete, lateral force resisting capacity and displacement results have been obtained by finite element analysis and compared for all the cases. Keywords: RC frame, Infill, Micro modelling, FEA, ABAQUS

The concrete shear walls of masonry structures with an RC frame on the first story are low-rise shear walls with a height–width ratio of less than 1. The strength, stiffness, and ductility of these low-rise shear walls are not matched, resulting in poor seismic performance. Based on the idea of the passive control theory and multi-seismic defensive lines, the scheme of a masonry structure with an RC frame on the first story with a concrete-filled steel tubular (CFST) damper is proposed in this paper. To explore the seismic mitigation effect of a CFST damper applied to a masonry structure with an RC frame on the first story, the seismic performance under low-reversed cyclic loading of the frame with the CFST damper is first compared with that of the energy-dissipated low-rise concrete shear wall proposed by previous researchers and the ordinary low-rise concrete shear wall. Furthermore, the response of the masonry structure model with an RC frame on the first story with a CFST damper and two other comparative structural models under earthquake action are discussed. The results show that a masonry structure with an RC frame on the first story with a CFST damper has a fuller hysteretic loop, lighter pinching, better energy dissipation ability, and better seismic performance. Compared with the other two structures, the energy dissipation capacity of the masonry structure with an RC frame on the first story with a CFST damper is significantly improved, by 1.25~1.5 times. The amplification effect of the deformation angle allows the CFST damper to play a significant role in energy dissipation, whereas the main structure still undergoes a small deformation. The CFST damper can dissipate more seismic energy to protect the main structure from damage and improve the seismic performance of masonry structures with an RC frame on the first story.

To further understand the seismic performance of reinforced concrete (RC) frame-shear wall structures, a 1/8 model structure is scaled from a main factory structure with seven stories and seven bays. The model with four-stories and two-bays was pseudo-dynamically tested under six earthquake actions whose peak ground accelerations (PGA) vary from 50[Formula: see text]gal to 400[Formula: see text]gal. The damage process and failure patterns were investigated. Furthermore, nonlinear dynamic analysis (NDA) and capacity spectrum method (CSM) were adopted to evaluate the seismic behavior of the model structure. The top displacement curve, story drift curve and distribution of hinges were obtained and discussed. It is shown that the model structure had the characteristics of beam-hinge failure mechanism. The two methods can be used to evaluate the seismic behavior of RC frame-shear wall structures well. What’s more, the NDA can be somewhat replaced by CSM for the seismic performance evaluation of RC structures.

The expansive polystyrene granule cement (EPSC) latticed concrete wall is a new type of energy-saving wall material with load-bearing, insulation, fireproof, and environmental protection characteristics. A series of shaking table tests were performed to investigate the seismic behavior of a full-scale reinforced concrete (RC) frame with EPSC latticed concrete infill wall, and data obtained from the shaking table test were analyzed. The experimental results indicate that the designed RC frame with EPSC latticed concrete infill wall has satisfactory seismic performance subjected to earthquakes, and the seismic responses of the model structure are more sensitive to input motions with more high frequency components and long duration. The EPSC latticed concrete infill wall provided high lateral stiffness so that the walls can be equivalent to a RC shear wall. The horizontal and vertical rebar, arranged in the concrete lattice beam and column, could effectively restrain the latticed concrete infill wall and RC frame. To achieve a more comprehensive evaluation on the performance of the RC frame with latticed concrete infill walls, further research on its seismic responses is expected by comparing with conventional infill walls and nonlinear analytical method.

Seismic design of standard structures is typically based on a force-based design approach. Over the years, this approach has proven to be robust and easy to apply by design engineers and – in combination with capacity design principles – it provided a good protection against premature structural failures. However, it is also known that the force-based design approach as it is implemented in the current generation of seismic design codes suffers from some shortcomings. One of these relates to the fact that the base shear is computed using a pre-defined force reduction factor, which is constant for a certain type of structural system. As a result of this, for the same design input, structures of the same type but different geometry are subjected to different ductility demands and show therefore a different performance during an earthquake. The objective of this research is to present an approach for computing force reduction factors using simple analytical models. These analytical models describe the deformed shape at yield and ultimate displacement of the structure and only require input data that are available when starting the design process, such as geometry and general material properties. The displacement profiles are obtained from section dimensions and section ductility capacities that can be estimated at the beginning of the design process. The so computed displacement ductility is taken as proxy of the force reduction factor. Such analytical models allow to link global to local ductility demands and therefore to compute an estimate of the force ductility reduction factors for wall and frame structures. Finally, this research develops an approach for frame-wall structures as combination of results obtained for wall and frame systems. The proposed method is applied to a set of frame-wall structures and validated by means of nonlinear time history analyses. Obtained results show that the proposed method yields a more accurate seismic performance than the current code design approach. The presented work therefore contributes to the development of revised force-based design guidelines for the next generation of seismic design codes.
La progettazione sismica di strutture è tipicamente basato su un approccio progettuale basato sulle forze. Nel corso degli anni, questo approccio ha dimostrato di essere robusto e facile da applicare dai progettisti e, in combinazione con il principio di gerarchia delle resistenze, fornisce una buona protezione contro i meccanismi di collasso fragili. Tuttavia, è anche noto che l'approccio di progettazione in forze così come attuato nell’odierna generazione di normative soffre di alcune carenze. Uno di questi riguarda il fatto che il tagliante alla base è calcolato utilizzando un fattore di struttura predefinito, cioè costante per tipo di sistema strutturale. Di conseguenza, per lo stesso input di progettazione, strutture dello stesso tipo ma diversa geometria sono sottoposti ad una diversa domanda di duttilità e mostrano quindi una diversa prestazione durante un evento sismico. L'obiettivo di questo studio è quello di presentare un approccio per il calcolo fattori di struttura utilizzando modelli analitici semplici. Questi modelli analitici descrivono la deformata a snervamento e spostamento ultimo della struttura e richiedono solo dati di input disponibili all’inizio del processo di progettazione, quali dati geometrici e proprietà dei materiali. La deformata della struttura ottenuta dalle dimensioni delle sezioni e la capacità in termini di duttilità sezionale possono essere stimati all'inizio della progettazione. La duttilità è alla base della formulazione del fattore di struttura come proposto dai modelli analitici presentati. Tali modelli analitici permettono di collegare le duttilità sezionali alla duttilità strutturale e quindi calcolare una stima del fattore di struttura per struttura a pareti e a telaio. Infine, si sviluppa un approccio per strutture duali di tipo telaio-parete come combinazione di risultati ottenuti per i sistemi singoli. Il metodo proposto è applicato ad un insieme di strutture duali e validato con analisi dinamiche non lineari. Si dimostra che il metodo proposto produce una più accurata prestazione sismica rispetto all'approccio progettuale delle normative odierne. Il lavoro presentato contribuisce pertanto allo sviluppo di nuove linee guida per la progettazione sismica nella prossima generazione di normative.

There is an excessive demand for the rehabilitation of frame type reinforced concrete (RC) buildings which do not satisfy current earthquake code provisions. Therefore, it is imperative to develop user-friendly seismic strengthening methodologies which do not necessitate the evacuation of building during rehabilitation period. In this study, it was aimed to strengthen the brick infill walls by means of diagonal Carbon Fiber-Reinforced Polymer (CFRP) fabrics and to integrate them with the existing structural frame in order to form a new lateral load resisting system. The possible effects of height to width (aspect) ratio of the infill walls and scale of the frame test specimens on the overall behavior attained by the developed rehabilitation methodology were investigated. The experimental part of the study was carried out in two steps. In the first step, ten individual panel specimens were tested in order to understand the behavior of strengthened/non-strengthened masonry walls under diagonal earthquake loads. And in the second step, the tests of eight 1/3 and four 1/2 scaled one-bay, two-story RC frames having two different aspect ratios were performed to determine design details. The experimental results were revealed in terms of lateral stiffness, strength, drift and energy dissipation characteristics of the specimens. In the analytical part, an equivalent strut and tie approach was used for modeling the strengthened/non-strengthened infill walls of the frames. The predicted pushover responses of the frame models were compared with the test results. The design criteria required for the aforementioned strengthening methodology was developed referring these analytical results.

The dynamic soil-structure interaction effects for RC framed buildings with or without shear wall on raft foundation is evaluated by explicit consideration of structural nonlinearity and soilstructure interaction as per Indian and Ethiopian seismic codes. In the current study, the finite element model (Elastic continuum approach) employed for soil-foundation-structure model. Hence, four and eight number of stories with or without shear wall on raft foundation found on rock, dense, stiff and soft soils are designed and modeled using SAP 2000 v 21. The building studied with or without incorporation of SSI effect. The analysis is carried out in 3 stages: (1) response spectrum analysis, (2) soil-structure interaction analysis, and (3) nonlinear structural analysis (pushover analysis). The response spectrum analysis is used to design the section sizes of the members and a comparison is made according to IS 456: 2000 and ES EN-2. The nonlinear static pushover analysis is used to observe proper structural behavior for defined push displacement. The resulting pushover curves are studied through performance-based design (PBD). Finally, a comparison is made between the behavior of each building in the fixed base condition and SSI condition. This work demonstrates ES ES-2 moments exceed that of the IS 456: 2000 by an average of about 15.58% for beam area of tension reinforcement for span and 15.4% for support. So, Indian code provides a more economical design than Ethiopian code ES EN-2. Moreover, the nonlinear response of buildings was determined and compared between two cases: fixed-base and SSI conditions. Response quantities such as SSI effects on the target displacement, SSI effects on the story drifts, SSI effects on the plastic hinge mechanisms and rotations obtained from pushover analysis of superstructure. The numerical findings indicate that incorporating the soil-structure interaction generally increases the top displacement and plastic hinge rotation, reduces the base shear. Hence, it is very important point is that soil-structure increases the plastic deformation.

碩士
國立臺灣科技大學
營建工程系
89
This research investigates the effect of brick walls on the seismic behavior of RC frame structures. Including the difference between brick-wall-infilled frame and bare frame in seismic resistance and some often seen failure mode in 921 Chi-Chi Earthquake : weak story failure , short -column failure and overturning failure. The brick wall filled in 5-story,10-story and 20-story frame with four layouts. The results of these structures under four acceleration records shown that : (1)Frames of 5-story and 10-story brick walls can enhanced seismic resistance performance obviously . But frames of 20-story , brick walls has little influence , excluded failure result from short-column effect. Brick-wall-infilled (2)Shear capacity of column which is designed with Old Code is not sufficient. (3)Columns of weak story generate plastic hinges more early during earthquake . These columns consume more earthquake energy then columns in other story. (4)Columns of brick-wall-infilled frame get larger maximun and less mininum axial force than columns in bare frame of the same position. (5)Plastic hinges generated during earthquake will more concentrated on lower level of brick-wall-infilled frames.

Il lavoro in questa tesi riguarda l’estensione, il miglioramento e la validazione della metodologia Simple Lateral Mechanism Analysis (SLaMA) per la valutazione sismica di strutture in CA. Raccomandato nelle linee guida neozelandesi del 2017 relative alla valutazione sismica, NZSEE (2017), SLaMA é un metodo di analisi non-lineare che permette di avere una stima della capacitá di strutture esistenti ed é valido per telai, pareti o sistemi misti telaio/parete. L’idea di base é procedere “dal locale al globale”, partendo dal comportamento di componenti singoli, estendendolo a specifici sottoschemi ed infine giungendo al comportamento globale dell’edificio. É anche possibile considerare gli effetti torsionali in campo non-lineare. Dato che il metodo si basa su ipotesi semplificate, non é necessario ricorrere a modelli numerici e i calcoli possono essere fatti “a mano (i.e. utilizzando un foglio elettronico). La prima parte di questo lavoro di ricerca riguarda i sistemi a telaio nudo, identificando aree di miglioramento della procedura SLaMA esistente e proponendo una procedura estesa e migliorata. Essa é stata validata attraverso la sua applicazione a 40 casi studio ideali e il confronto con i risultati di analisi numeriche raffinate (FEM Pushover). I risultati indicano che la procedura SLaMA modificata permette di identificare accuratamente il meccanismo plastico del telaio, considerando l’effettiva gerarchia delle resistenze dei suoi componenti, e di calcolarne la curva di capacitá con errori accettabili per i suoi parametri più significativi. La parte successiva del lavoro riguarda lo sviluppo di una nuova procedura SLaMA, non presente in NZSEE (2017), per sistemi a telaio tamponato, che rappresentano una cospicua parte del patrimonio edilizio, soprattutto in Europa. La nuova metodologia si basa su una procedura meccanica, proposta in questo lavoro, per disaccoppiare i contributi al taglio alla base relativi al telaio e alle tamponature, per un qualunque valore dello spostamento globale. La procedura di disaggregazione é applicabile a prescindere dalla distribuzione delle tamponature e della curva caratteristica dei puntoni equivalenti. Puó essere inoltre applicata per la post-processione dei risultati di analisi Pushover o Time History di telai tamponati. In analogia a quanto fatto per i telai nudi la procedura SLaMA é stata validata tramite confronto con i risultati di analisi Pushover per 72 casi studio. Sono stati inoltre considerati i sistemi resistenti misti telaio/parete con l’obiettivo di proporre una nuova procedura SLaMA che considerasse esplicitamente l’interazione tra la parte a telaio con quella a parete, includendo il calcolo delle forze da essi scambiate e le eventuali coppie concentrate dovute alla presenza di travi di collegamento. Con la nuova procedura SLaMA é possibile stimare il comportamento dei sistemi duali con grande accuratezza, come dimostrato da una vasta analisi parametrica (SLaMA vs Pushover) che coinvolge 24 casi studio. L’ultima parte del lavoro riguarda la valutazione sismica di un edificio realmente esistito e che ha subito notevoli danni durante la sequenza sismica di Christchurch (Nuova Zelanda) tra il 2010 e il 2011. Lo “score sismico” (capacitá fratto domanda) é stato indipendentemente valutato con diversi metodi di analisi: Lineare Statica, Lineare Dinamica, Non-Lineare Statica (Pushover e SLaMA), Non-Lineare Dinamica. In primis questo confronto incrociato dimostra l’affidabilitá del metodo SLaMA nella valutazione di casi reali complessi. Questo studio dimostra inoltre come le informazioni ottenute utilizzando SLaMA possano essere efficacemente usate per calibrare i parametri fondamentali necessari per gli altri metodi di analisi, o interpretarne i risultati. Sebbene alcuni passi della procedura possono essere calibrati in maniera piú raffinata grazie a sviluppi futuri si puó sicuramente affermare che SLaMA sia un metodo di analisi robusto. Esso é in grado di fornire al tecnico valutatore gli strumenti per comprendere i dettagli del comportamento di un edificio usando esclusivamente calcoli fatti a mano (eventualmente implementati in un semplice foglio elettronico).
This dissertation is focused on the extension, refinement and validation of the Simple Lateral Mechanism Analysis (SLaMA) method for the seismic assessment of RC buildings. Suggested in the 2017 New Zealand guidelines for seismic assessment, NZSEE (2017), SLaMA is an analytical non-linear analysis technique that provides a first estimation of the global capacity curve of the primary lateral-resisting systems in RC buildings, including bare frames, cantilever walls and dual wall/frame systems. The basic idea is to progress “from local to global”, extending the local behaviour of the structural members to selected sub-schemes, and finally to the global non-linear response of the building. Inelastic torsional effects are also included. Since simplified assumptions are made, no numerical computer model is needed and hence all the calculations can be performed “by hand” (i.e. implemented in an electronic spreadsheet). The first part of this investigation is related to bare frame Lateral Resisting Systems, with the identification of potential areas of improvement for the existing SLaMA procedure and the proposal of an extended/refined one. The refined procedure for bare frames is validated through the application to a set of 40 ideal case studies and the comparison with refined numerical analyses (FEM Pushover). The results show that the refined SLaMA procedure allows to accurately identify the expected plastic mechanism of the frame, also considering the actual hierarchy of strength of its members, and to properly estimate its non-linear capacity curve with acceptable errors on the most meaningful parameters. The subsequent part of the investigation involves the development of a novel SLaMA method to evaluate the capacity curve of masonry-infilled frames systems, which represent a large portion of the building portfolio, especially in Europe. The incorporation of the contribution of the infills is completely absent in the NZSEE (2017) SLaMA framework. The methodology is based on a proposed mechanically-based procedure to decouple the frame and infills contributions to the overturning moment (and hence base shear) capacity for any value of the global displacement. The decoupling procedure is applicable regardless of the distribution of the infills and of the non-linear Axial load-Axial strain of the equivalent struts. It can be applied to post-process the results of Pushover or Time History analyses of different types of infilled frames (material-wise). Similarly to what done for bare frames, an extensive SLaMA vs numerical Pushover comparison, for a set of 72 ideal case studies, is used to validate the proposed SLaMA procedure. Part of the investigation is dedicated to dual wall/frame system structures, proposing a novel SLaMA procedure in which the coupled behaviour of the frame and wall(s) components is expressly considered, including the calculation of the exchanged forces and the concentrated moment couples due to the possible presence of link beams. By using the new SLaMA procedure it is possible to capture the non-linear behaviour of the dual system with extreme accuracy, as demonstrated with an extensive SLaMA vs numerical Pushover parametric analysis comprising 24 ideal case studies. The last step of the work is the seismic assessment of a real case study building, severely damage in the Christchurch (New Zealand) sequence of earthquakes in 2010-2011. Different analysis techniques are used to independently derive the “seismic score” of the building (capacity over demand), including: Linear Static, Linear Dynamic, Non-Linear Static (numerical Pushover and SLaMA) and Non-Linear Dynamic analyses. Firstly, this demonstrates the reliability of the SLaMA method in assessing real, complex cases by means of a cross-validation. Moreover, and perhaps more importantly, it is deemed that this comparative study demonstrates how the insights gained by using SLaMA can be used to calibrate important parameters needed when adopting other analysis techniques, or interpreting their results. Additional investigations might help in fine-tuning some of its steps but, overall, it is deemed that SLaMA constitutes a robust analysis technique that allows the assessor to really understand the behaviour of an RC building only using hand calculations, possibly implemented in a simple spreadsheet.

Strengthening of non-ductile public buildings is a never-ending issue. Selection of the suitable strengthening method and appropriate analysis type for the assessment of pre- and the post-intervention performances are still open to question. The displacement or drift limitations are crucial as well as demand capacity ratios for determination of such buildings performance under severe ground motion. In this chapter, an investigation of seismic performance focused on displacement criterion of strengthened non-ductile public RC buildings in Turkey is presented. Both the nonlinear static and response history analysis were conducted. Friction dampers which are fairly modern technique and conventional RC wall implementation method were introduced to as-is building. For the simplicity and the easy of the process, 2D frame selected for investigation. Comparison of the aforementioned techniques for non-ductile public RC buildings and performances particularly by means of displacement obtained using different methods for those investigated schemes are carried out and presented in the chapter.

The function of infilled masonry reinforced concrete (RC) frame buildings during severe events such as blast caused by explosions or earth movement – earthquake and other significant lateral displacement could seriously damage a supporting frame column, causing the frame to collapse completely or partially. The behaviour of a framed structure associated with loss of supporting column as a result of vertical gravitational loading imbalance has received less attention in recent studies. When a supporting column is removed in a framed structure, it is assumed that the member deflection increases significantly, which could be restrained by the infill wall, resulting in contact forces between the infill wall and the frame. These interaction forces have an impact on the distributions of shear forces and bending moments along the frame components, which can contribute to frame stability or failure. The current study aims to address these key issues and gain insight into the performance of infilled-frame activity in the absence of a peripheral supporting column. This study’s methodology is based on a numerical investigation of a typical RC infilled-frame subjected to gravitational loading using the three-dimensional discrete element code (3DEC) model. The scenarios considered include; investigation of the loaded structure with the column in place, without the column in place but supported by an infilled wall and with the effect of lateral load acting on the structure without a peripheral column support. The results indicate that masonry infill walls considerably increase the frame resistance to vertical load action, compared to the resistance of a bare frame up to 18%, therefore, the infill wall could play a major role in maintaining the structural system stability/integrity and reducing the likelihood of a progressive collapse.

<p>This study investigates the structural vulnerability of an old reinforced concrete dual wall-frame building structure, in Lisbon, Portugal. The building presents non-ductile behaviour and detailing typical of buildings designed before the introduction of modern seismic codes (pre– 1980). An analytical methodology is adopted in which multiple stripe analysis are performed on a three- dimensional model of the building. Fragility and vulnerability functions are developed for this structure, representative of a typology of old RC buildings. The fragility is derived taking into account the brittle shear failures of RC vertical members, i.e. columns and shear walls. The nonlinear dynamic analyses clearly indicate that these failure modes have a critical influence on the seismic performance of the structure. The results of this study can be used for seismic loss assessment and for the identification of appropriate mitigation strategies for this typology of existing RC buildings.</p>

Abstract Reinforced Concrete (RC) frame structures that were designed and built according to older standards can be damaged during destructive earthquakes as a result of insufficient lateral strength and/or deformation capacity. Such structures must be retrofitted to satisfy the current requirements and to survive future earthquakes. Owing to its high lateral strength and stiffness capacity of an RC wall, the post-installation of an RC wall in a non-ductile frame for retrofit is a widely used retrofitting technique. However, for frame structures with low-strength concrete, the typically used connected construction method on the interface between existing and new concrete may be not able to provide effective force transfer, and may cause unexpected brittle failure in the retrofitted structure. Such unexpected brittle failure may reduce the seismic capacity of the structure and threaten its safety. Therefore, in this experimental investigation, two retrofitting methods that use a post-installed RC wall are proposed to improve the load transfer mechanism on the interface. The first involves a wall with diagonal rebar and boundary spirals, and the second involves a wall with an additional inner frame. A typical traditional retrofitting specimen was constructed and tested for comparison. Reversed cyclic loading is used to test the seismic capacity of the specimens. Finally, post-embedded piezoceramic-based sensors were used to monitor the structural health and detect damage in one of specimens during the test. The experimental results demonstrate the effectiveness of the piezoceramic-based approach to structural health monitoring and the ability of the method to detect damage in shear governed RC structures under seismic loading.

<p>As a new type of structural system, hybrid masonry (HM) structure with reinforced concrete (RC) frame is constructed of reinforced block masonry wall and reinforced concrete frame. This structural system combines the advantages of reinforced concrete frame structure and reinforced concrete block masonry structure, also overcomes some limitations of them. In order to study the seismic performance of the structural system, the lateral reversed cyclic loading experiment on the HM structure with RC frame was conducted. In the experiment, two specimens that were constructed with different connecting type were designed and tested, in one of them the masonry blocks was separated from the RC frame and only connected with steel keys at the top part of the specimen, while in the other there was no spacing between the RC frame and the masonry blocks. According to the data of the experiment, the paper analyzed the failure process and patterns, hysteretic characteristic, skeleton curve, stiffness degradation and displacement ductility of the structural system, and compared the results of the two specimens. The experimental study indicated that the HM structure with RC frame showed extraordinary good seismic performance during testing, and this form of construction had fairly good displacement ductility and energy dissipation, which would provide a basis for further theoretical analysis and design method.</p>

<p>Using an appropriate structural system is critical to good seismic performance of buildings. While moment- frame is the most commonly used lateral load resisting structural system, addition of other structural systems like structural walls, frame-wall system improve the seismic resistance. Structural system chosen should be suitable for good earthquake performance, with vertical and horizontal members of lateral load resisting system (LLRS) that can carry earthquake effects safely during strong earthquake shaking. Studies on real structures, practically adopted are negligible. Present work deals with the comparison of seismic performance of the structural system under consideration with existing features (Lift core RC wall &amp; Infill effect along the boundary walls) as LLRS in the building using response spectrum and time history method..</p>

Abstract This paper describes the work conducted by the Canadian Nuclear Safety Commission (CNSC) related to the numerical simulations of reinforced concrete (RC) structures under deformable missile impact. The current paper is a continuation of the work conducted in the frame of the OECD/NEA* IRIS (Improving Robustness Assessment Methodologies for Structures Impacted by Missiles) Phase 3 benchmark project. The concrete mock-up with two simple structures attached, one welded and another bolted, was built and tested at the VTT Technical Research Centre in Espoo, Finland. This mock-up was impacted by three subsequent missiles with varying velocities in order to obtain the damage accumulation. To examine vibration transmission through the mock-up, the simple structures modelling equipment were attached to the rear wall of the structure, while the missile impact was at the centre of the front wall. The parameters of the missiles and the RC structure were selected to ensure a flexible behaviour of the RC target in the impact area with only moderate damages, specifically cracking and permanent deformation without perforation. The non-linear dynamic behaviour of the reinforced concrete slabs under missile impact was analyzed using the commercial FE code LS-DYNA. A hybrid FE model using both 3-D solid and 2-D shell FE models was developed for the target discretization. Since the ultimate objective of this work is to model the entire structure over long time periods, a simplified combined shell-solid model with distributed (smeared) reinforcement was selected and validated. This model employs solid FE around an impact area and shell FE for the rest of the mock-up. Detailed modelling of a large RC structure with all equipment attached leads to a very large finite element (FE) model. Therefore, two-level FE modelling using sub-modelling approach was employed: first, analyze the vibrations of a reinforced concrete structure with simplified equipment modelling, and second, analyze in detail the equipment connected to it. This approach assumes uncoupled dynamic behaviour of the structure and the equipment. While the sub-modelling technique is commonly used in static analysis, a special sensitivity analysis was conducted to prove the applicability of sub-modelling for impact analysis. Finally, the effect of structural damping was examined and the best possible damping was selected. The selected damping values and sub-models resulted in relatively good agreement with the test results for both global (RC mock-up) and local (equipment) behaviour.

This paper presents the results of the experimental and analytical investigations conducted on four 0.8 scale 2-story one bay ductile reinforced concrete frames with infill nonstructural walls subjected to cyclically increasing loads. The material properties and the member sizes of beams and columns in the four RC frame specimens are identical, but with different types of infill nonstructural wall. These four frames are the pure frame, frame with short column, frame with short beam and frame with wing walls. The four RC frame specimens were designed and constructed according to the general prototype building structures in Taiwan. Test results indicate that the ductility behavior of the frames with infill wall is similar to those of the pure frame. The ultimate base shear strength of the frames with infill walls is higher than those of the pure frame. Analytical results show that the proposed simplified multi-linear beam-column element implemented in a general purpose structural analysis program can accurately simulate the cyclic responses of the RC frame specimen incorporating the elastic flexural stiffness computations suggested by the model building codes.