Concrete Shear Wall Structures Research Articles

Anti-seismic Analysis of Masonry-Reinforced Concrete Composite Structure Based on LS-DYNA

Previous great earthquakes have performed serious structural damages to masonry structure, which also have caused great casualties and property damage, in order to enhance the structural anti-seismic class of civilian buildings, a new kind of combined structure form is introduced in the thesis, which is formed by two parts, masonry structure and special reinforced concrete shear wall structure. The reinforced concrete part can be effective in enhancing the anti-seismic performance of masonry residence, besides reinforced concrete tube structure can also become the nearest refuge when disaster occurred, even when the whole structure collapse, it can still remain relatively complete partial structures and a large space of survival. LS-DYNA, software of finite element, is used to study the structure, simulations of the response procedures of composite structure under earthquake load are made, as well as the destruction of composite structure. According to calculation and analysis, it can be known that this kind of composite structure can obviously improve seismic resistant capability, and the level of destruction is relative smaller, which can meet the requirements for fortification against earthquake that is "keeping intact in minor earthquakes, repairable in medium earthquakes, standing upright in major earthquakes"

Study on Strain Rate Effect in High-Rise Reinforced Concrete Shear Wall Structure

The dynamic behavior affected by strain rate effect of the high-rise reinforced concrete shear wall structure subjected to seismic loading are analyzed by finite element software ABAQUS. The damaged plasticity model for concrete was used, and the strain rate effect of concrete and steel were considered. The nonlinear dynamic response results with strain rate effect are compared with the results without strain rate effect. The distribution of strain rate can not only influence the concrete and steel, but also have some effects on the dynamic response of the high-rise reinforced concrete shear wall structure. The strain rate effect is more prominent under the stronger seismic wave.

Health monitoring of reinforced concrete shear walls using smart aggregates

In this paper, a smart aggregate-based approach is proposed for the structural healthmonitoring of a concrete shear wall structure. The piezoceramic-based smart aggregateswere distributed in predetermined locations prior to the casting of the concrete structure toform an active-sensing system for the health monitoring purpose. To evaluate the damagein different areas, the concrete shear wall was sectioned into sub-domains and awavelet-packet-based damage index matrix is proposed to evaluate the health status inthese sections. A cyclic loading procedure was applied to gradually fail the concrete shearwall and the proposed structural health monitoring approach was used to performstructural health monitoring during this loading procedure. The experimental results haveshown that the proposed smart aggregate-based approach effectively evaluated thedamage status in different areas and detected the precautionary point to predictthe structural failure. The proposed approach has the potential to be applied tothe structural health monitoring of large-scale concrete shear wall structures.

A blind prediction test of nonlinear analysis procedures for reinforced concrete shear walls

A full scale slice of a 7 story reinforced concrete building was tested on the shake table at the UCSD Engelkirk Structural Research Centre in 2006. As part of the research project, a blind prediction contest was sponsored to assess the capability of currently available analysis procedures to predict the seismic response of cantilever reinforced concrete shear wall structures. This paper describes an entry based on a nonlinear finite element model, using macro elements to represent both the shear and the flexural modes of behaviour. A comparison of the predicted response with the test results showed that the analysis procedure produced reasonable predictions of deformations for the lowest and highest of the four earthquakes but under-estimated response for the two moderate earthquakes by approximately 30%. For all earthquakes, the analysis base moment was much lower than the test value. Modifications to the procedure to improve the correlation were identified and implemented but did not remedy the deficit in base moments. Detailed results of the test program revealed that the causes for this discrepancy were the contribution to overturning results of gravity columns and the flange wall, neither of which had been included in the model. When these were incorporated the average error between test and analysis results was less than 10% for all earthquakes, well within acceptable limits for a design office type of model. The correlation of tests and analysis also provided useful information on design aspects for shear walls, such as the influence of secondary components and dynamic magnification factors.

Nonlinear analysis of reinforced concrete shear wall structures

Although shear walls are a widely used system for providing lateral load resistance, nonlinear analysis procedures for this type of element are much less well developed than those for frame and truss elements. Equivalent flexural models do not include shear deformation and are only suited for symmetric, straight walls. This paper describes the development of an analysis model which includes nonlinear effects for both shear and flexure. The formulation is based on a "macro" modelling approach which is suitable for complete building models in a design office environment.
 An analysis methodology is developed using engineering mechanics and experimental results and implemented in an existing nonlinear analysis computer program. A model is developed and validated against test results of solid walls and walls with openings. This shows that the model can capture the general characteristics of hysteretic response and the maximum strength of the wall. Results can be evaluated using acceptance criteria derived from published guidelines. An example shear wall building is then evaluated using both the nonlinear static and the nonlinear dynamic procedures. The procedure is shown to be a practical method for implementing performance based design procedures for shear wall buildings.

Analysis of reinforced concrete coupled shear wall structures

The ultimate strength analysis of reinforced concrete coupled shear walls with one or two bands of openings requires a two-stage approach. In the first stage, the analysis of the coupling beams is carried out. This is followed by the analysis of the complete wall in the second stage. A simple approach based on the ‘total moment concept’ for the analysis of coupled shear walls with one or two bands of openings is presented. Experimental results supporting the predictions of the mode of failure and ultimate strength is also presented. This study updates previous research and enhances further understanding of the behaviour of reinforced concrete shear wall structures at ultimate limit states of loading. Copyright © 1999 John Wiley & Sons, Ltd.

Stochastic response analysis of visco-elastic slit shear walls

Slit shear walls an reinforced concrete shear wall structures with purposely built-in vertical slits. If the slits are inserted with visco-elastic damping materials, the shear walls will become viscoelastic sandwich beams. When adequately designed, this kind of structures can be quite effective in resisting earthquake loads. Herein, a simple analysis method is developed for the evaluation of the stochastic responses of visco-elastic slit shear walls. In the proposed method, the stiffness and mass matrices are derived by using Rayleigh-Ritz method, and the responses of the structures are calculated by means of complex modal analysis. Apart from slit shear walls, this analysis method is also applicable to coupled shear walls and cantilevered sandwich beams. Numerical examples are presented and the results clearly show that the seismic responses of shear wall structures can be substantially reduced by incorporating vertical slits into the walls and inserting visco-elastic damping materials into the slits.

Dynamic non-linear analysis of reinforced concrete shear wall by finite element method with explicit analytical procedure

A numerical procedure for a dynamic non-linear finite element analysis is proposed here to analyse three-dimensional reinforced concrete shear wall structures subjected to earthquake motions. A shear wall is modelled as a quasi-three dimensional structure which is composed of plane elements considering the in-plane stiffness of orthogonal flange panels. The proposed constitutive model is based on the non-linearity of reinforcement and concrete in which the tension stiffening in tension and the degradation of stiffness and strength in compression of concrete after cracking are considered. The acceleration-pulse method, which is a kind of explicit analytical procedure, is employed to solve the non-linear dynamic equations, where the dynamic equation can be solved without stiffness matrix and so the iterative procedure is not necessary for descending portion of stress–strain relationship caused by cracking and softening after compressive strength in concrete. The damping effect is considered by assuming equivalent viscous damping which can give good cyclic behaviours of inertia force vs. displacement relationships. This analytical method was applied to a test specimen of a reinforced concrete shear wall with a H-shaped section which was vibrated up to failure by using a large-scale shaking table with high -performance in Japan. The test was performed as one of the dynamic model tests for evaluation of seismic behaviour of nuclear reactor buildings. The calculations were performed sequentially from the elastic range to failure. The comparison with the test results shows that this approach has good accuracy. © 1997 by John Wiley & Sons Ltd

Dynamic non‐linear analysis of reinforced concrete shear wall by finite element method with explicit analytical procedure

A numerical procedure for a dynamic non-linear finite element analysis is proposed here to analyse three-dimensional reinforced concrete shear wall structures subjected to earthquake motions. A shear wall is modelled as a quasi-three dimensional structure which is composed of plane elements considering the in-plane stiffness of orthogonal flange panels. The proposed constitutive model is based on the non-linearity of reinforcement and concrete in which the tension stiffening in tension and the degradation of stiffness and strength in compression of concrete after cracking are considered. The acceleration-pulse method, which is a kind of explicit analytical procedure, is employed to solve the non-linear dynamic equations, where the dynamic equation can be solved without stiffness matrix and so the iterative procedure is not necessary for descending portion of stress–strain relationship caused by cracking and softening after compressive strength in concrete. The damping effect is considered by assuming equivalent viscous damping which can give good cyclic behaviours of inertia force vs. displacement relationships. This analytical method was applied to a test specimen of a reinforced concrete shear wall with a H-shaped section which was vibrated up to failure by using a large-scale shaking table with high -performance in Japan. The test was performed as one of the dynamic model tests for evaluation of seismic behaviour of nuclear reactor buildings. The calculations were performed sequentially from the elastic range to failure. The comparison with the test results shows that this approach has good accuracy. © 1997 by John Wiley & Sons Ltd

Case study

The Government Building in Christchurch was purchased by the Christchurch City Council in 1992, to avoid possible demolition. After a period in which no developers could be found, the building is to be strengthened and refurbished for use primarily as apartments. The strengthening scheme adopted involves demolition of two areas of the building which are otherwise difficult to use, and replacement with new reinforced concrete shear wall structures. This has resulted in more useable space, and has allowed strengthening to full code loads. Work will be completed in late 1996.

SHAKE-TABLE TESTS OF LARGE-SCALE SHEAR WALL AND INFILLED FRAME MODELS.

In order to evaluate and compare the seismic performance of different types of wall construction, three 1/3 scale four-storey models of structural walls were tested dynamically to ultimate failure by subjecting each of them to a sequence of simulated earthquakes of progressively increasing magnitude on a 5m x 5m shaking table. The three models tested are respectively : a reinforced concrete shear wall structure ; a masonry infilled reinforced-concrete frame structure ; and a concrete infilled frame structure.

Nonlinear dynamic analysis of reinforced concrete shear wall structures

During strong ground motions, structural members made of reinforced concrete undergo cyclic deformations and experience permanent damage. Members may lose their initial stiffness as well as strength. Recently, Los Alamos National Laboratory has performed experiments on scale models of shear wall structures subjected to recorded earthquake signals. In general, the results indicated that the measured structural stiffnesses decreased with increased levels of excitation in the linear response region. Furthermore, a significant reduction in strength as well as in stiffness is also observed in the inelastic range. Since the in-structure floor response spectra which are used to design and qualify safety equipment have been based on calculated structural stiffness and frequencies, it is possible that certain safety equipment could experience greater seismic loads than were specified for qualification due to stiffness reduction. In this research, a hysteresis model based on the concept of accumulated damage has been developed to account for this stiffness degradation both in the linear and inelastic ranges. Single and three-degrees-of-freedom seismic Category I structures were analysed and compared with equivalent linear stiffness degradation models in terms of maximum displacement responses, permanent displacement, and floor response spectra. The results indicate significant differences in response between the hysteresis model and equivalent linear stiffness degradation model at PGA levels of greater than 0.8 g. The hysteresis model is used in the analysis of reinforced concrete shear-wall structures to obtain the in-structure response spectra. Results of both cumulative and one shot tests are compared.

Comparison of Earthquake Simulator Test Results with the SEAONC Tentative Seismic Isolation Design Requirements

Earthquake simulator tests were performed on a 1/5-scale, 6-story reinforced concrete shear-wall structure and a 1/4-scale, 9-story braced steel frame structure. The structures were supported by five different base isolation systems which consisted of various types and combinations of elastomeric bearings. The main objective of this study was to compare the peak experimental displacements of the base isolation systems tested with values given by the tentative base isolation design provisions proposed by the Seismology Committee of the Structural Engineers Association of Northern California (SEAONC). Comparisons of experimental results and values from the SEAONC base isolation design formula for displacements indicated that the formula is generally conservative, even for predominantly low frequency earthquake motions, provided the ground motion coefficient Av (based on the effective peak velocity as defined by ATC 3-06) is used in the design equation for base-isolated structures with periods greater than 1 second.

傾斜地における壁式プレキャスト鉄筋コンクリート造住宅の施工

横浜市旭区白根町において, 現在, 斜面住宅を建設中である。敷地面積は約3.6ha, 敷地内の傾斜は平均18°である。特徴として, (1) 延床面積約23600m2, 戸数243戸, 棟数17と, 斜面住宅としては規模が大であること, (2) 基礎部分を除き, すべてプレキャスト化していること, (3) 部分的に地盤改良を併用していること, (4) 提案設計方式による設計施工であること, 等があげられる。本稿は, これらの特徴をもつ白根団地 (仮称) の設計概要と施工について述べるものである。

Optimum design of reinforced concrete shear walls

The recently published New Zealand Code of Practice for the Design of Concrete Structures (NZS 3101:1982) and the newly amended Code of Practice for General Structural Design and Design Loadings for Buildings (NZS 4203) permit a variety of possible design approaches for reinforced concrete shear wall structures. A series of wall designs for dimensionally similar four-storey and eight-storey buildings has been carried out and a comparison of construction cost estimates obtained together with an assessment of the relative design effort required for the different design options.

A proposal for the compatibility of static and dynamic seismic base shear provisions of the National Building Code

A comparison is made, based on static and dynamic base shear calculations according to the National Building Code of Canada of 1980, for four types of simple structures, namely, uniform moment resisting frame structures, uniform ductile flexural wall structures, uniform reinforced concrete shear wall structures, and unreinforced masonry wall structures. It is shown that a significant discrepancy exists between the static and dynamic base shear values, depending on the type and the fundamental period of the structure. The causes for the discrepancy and the necessity to make static and dynamic base shears compatible are discussed.

The analysis and design of and the evaluation of design actions for reinforced concrete ductile shear wall structures

A comprehensive review of the state of the art in the design of earthquake resisting ductile structural walls is presented. The material has been compiled from the technical literature, the deliberations within the New Zealand National Society for Earthquake Engineering and research efforts at the University of Canterbury. The paper attempts a classification of structural types and elaborates on the hierarchy in energy dissipation. After a review of available analysis procedures, including modelling assumptions, a detailed description of capacity design procedures for both cantilever and coupled shear wall structures is given. The primary purpose of capacity design is to evaluate the critical design actions which can be used in the proportioning and reinforcing of wall actions which can be used in the proportioning and reinforcing of wall sections. An approach to the estimation of structural deformation is suggested. To satisfy the ductility demands imposed by the largest expected earthquake, detailed design and detailing recommendations are given and the application of some of these is presented in an appendix.

Analysis of RC Shear Panels under Cyclic Loading

A nonlinear constitutive model for plain concrete subjected to cyclic biaxial stresses is described in brief. The model takes account of the compressive softening of concrete prior to reaching maximum compressive stress. Two reinforced concrete shear wall structures, one loaded monotonically and the second subjected to large cyclic load reversals are analyzed and compared with test data. Simulation of cyclic loading response is greatly improved compared to previous elastoplastic models. In addition to the improved material characterization in compression, the treatment of tensile cracking is felt to be a significant factor in the good match obtained with experimental data.

Response of a reinforced concrete shear wall structure during the 1972 Managua earthquake

The 1972 Managua, Nicaragua earthquake was a severe test of modern earthquake resistant design and construction procedures. This paper examines the behaviour of the 18-story reinforced concrete Banco de America building which performed exceptionally well during the earthquake. Although the building suffered some structural and non-structural damage, its large, symmetrically located, coupled shear walls limited this damage to levels significantly below those observed in more flexible structures. Several linear elastic and nonlinear analyses were conducted to evaluate the building's behaviour and determine the probable cause of the observed damage. Both static and dynamic elastic analyses were used to determine the members that would have failed and the consequence of these failures on the subsequent dynamic response. The effects of biaxial ground motions, foundation flexibility and ground motion characteristics were considered in the elastic investigations. To get a better idea of the dynamic behaviour of the principal lateral force resisting system considered in the design, nonlinear analyses were performed for the coupled shear wall cores as constructed and for the idealized case where the coupling girders were assumed to have unlimited ductility. Even code type static analyses satisfactorily identified the damaged regions. The principal design deficiency was the low shear strength of the coupling girders. However, the nonlinear results indicated that had these girders been able to develop their flexural capacity they would have suffered substantial numbers of reversals and the shear walls would have been subjected to undesirable states of stress. The analytical results as well as the building’s performance demonstrated that buildings with coupled shear walls combined with moment resisting frames offer excellent protection against seismic excitations, minimizing nonstructural damage while providing several lines of defense in the event of localized failure. Design and repair recommendations are offered.

壁式 RC 構造に関する基礎的研究 : 組合せ応力 M. N. Q. を受ける二方向壁体の耐力, 剛性の実験的研究並びに理論的検討

壁式 RC 構造に関する基礎的研究 : 組合せ応力 M. N. Q. を受ける二方向壁体の耐力, 剛性の実験的研究並びに理論的検討