Concrete Structural Walls Research Articles

杭基礎で支持された曲げ降伏型連層耐震壁の地震時抵抗機構

Reinforced concrete multi-story structural walls supported on pile foundations are commonly designed assuming that they stand on solid foundation without considering their interaction. In this study, parametric studies with a two-dimensional finite element model were conducted in order to simulate their seismic-force-resisting mechanisms. The numerical model was first calibrated using the experimental data on three-story structural wall with pile foundation. The main analytical variable was the amount of upper longitudinal reinforcement in the foundation beam. Failure modes, deformation capacity and damage process of the numerical models varied depending on whether the upper longitudinal reinforcement in the foundation beam yielded in tension or not. The procedure for calculating moment acting on the foundation beams in the flexural ultimate state of the structural walls was established.

Evaluation of Structural Capacity of SC Walls in Nuclear Power Plant accounting for the Area Lost to Openings

지금까지 수행된 개구부가 존재하는 벽체에 대한 연구는 대부분 RC 벽체에 대해서 수행되었으며, SC(Steel plate Concrete) 벽체에 설치되는 개구부에 대한 연구는 수행된 예가 적다. 최근에 국내에서 개발된 SC 벽체는 원전구조물에 일부 적용되고 있지만, 관련 설계기준인 KEPIC-SNG에서도 개구부를 갖는 SC 벽체에 대한 설계법은 명확하게 정의되지 않았다. 본 연구에서는 원전구조물내 벽체에 설치되는 SC 벽체를 대상으로 개구 저감률이 구조내력에 미치는 영향을 평가하였다. 개구 저감률을 고려한 구조내력 평가 결과는 실험 및 수치해석 결과와 비교분석하였다. The shear wall with openings built with reinforced concrete(RC) have been elaborately studied by many researchers, whereas the steel plate concrete(SC) wall structure has not been investigated as much. Recent SC wall structures developed in Korea have been partly applied to nuclear power plant structures, although its design specification or guideline for the SC wall structure with openings has not been completed yet. This study based on the account for the area lost to openings evaluates the effects of opening on the structural capacity of the SC structure within nuclear power plant. The results obtained from the study on the area lost to openings have been compared with experimental and numerical studies.

Seismic Performance Assessment of Partially Grouted, Nominally Reinforced Concrete-Masonry Structural Walls Using Shake Table Testing

An experimental program has been carried out to study the performance of partially grouted, nominally reinforced (PG-NR) concrete block structural walls under in-plane seismic loading on a shake table. Five reduced-scale structural walls were constructed and tested under scaled versions of the 1940 El Centro, California earthquake, using its N-S component record with a constant axial compression load that represented a single-story building. The test walls were grouped into three categories. Type I and III walls had reinforcement at the wall end cells only, with vertical reinforcement ratios of 0.07 and 0.12%, respectively, based on the gross cross-sectional area of the walls. Type II walls were similar to Type I walls, but with an additional reinforcement bar located midlength of the wall with a vertical reinforcement ratio of 0.10%, also based on the gross cross-sectional area of the wall. The experimental results were documented and discussed with respect to wall lateral load capacity, stiffness degradation, period shift, displacement ductility levels attained, and relevant seismic-force reduction factors. The test results showed that PG-NR masonry walls can comprise a ductile seismic force-resisting system. Subsequently, PG-NR masonry walls have the potential to bridge the gap between unreinforced and reinforced masonry systems. The use of PG-NR masonry also results in a reduced cost compared with traditional reinforced masonry systems used in seismic zones that are typically fully grouted within the plastic hinge zones and require higher reinforcement ratios.

개구부를 갖는 원전 SC구조 벽체의 구조거동 평가

지금까지 수행된 개구부가 존재하는 벽체에 대한 연구는 대부분 RC 벽체에 대해서 수행되었으며, SC(Steel plate Concrete) 벽체에 설치되는 개구부에 대한 연구는 수행된 예가 적다. 최근에 국내에서 개발된 SC 벽체는 원전구조물에 일부 적용되고 있지만, 관련 설계기준인 KEPIC-SNG에서도 개구부를 갖는 SC 벽체에 대한 설계법은 명확하게 정의되지 않았다. 본 연구에서는 원전구조물내 벽체에 설치되는 SC 벽체를 대상으로 개구부가 구조내력에 미치는 영향을 해석적 방법에 의해서 평가하였다. 비선형 해석 결과, 개구부가 설치되는 SC 벽체는 개구부 주변의 보강 여부가 내력에 미치는 영향이 크기 때문에 개구부 주변에 일정범위 이상의 보강이 이루어져야 하며, 개구부 주변이 보강된 경우는 개구부의 형상, 크기, 위치 및 설치개수에 관계없이 충분한 내력 및 연성을 확보할 수 있는 것으로 나타났다. The shear wall with openings built with reinforced concrete (RC) have been elaborately studied by many researchers, whereas the steel plate concrete (SC) wall structure has not been investigated as much. The recent SC wall structures developed in Korea have been partly applied to nuclear power plant structures, although its design specification or guideline for the SC wall structure with openings has not been completed yet. This study based on numerical analysis evaluates the effects of opening on the structural resistance of the SC structure in nuclear power plant. As a result from nonlinear analysis, since the strengthening for openings significantly affect the overall strength of SC wall, the openings should be considered to strengthen them around adjacent area. It is also proved that the strengthened openings have the sufficient resistance and ductility regardless their size, shape, location, and quantity.

Deformation Limits for Structural Walls with Confined Boundaries

For accurate analytical assessment of performance and damage in reinforced concrete members, well-defined deformation limits at particular damage states are required. With advanced and computationally intensive finite element analyses, we establish deformation limits at yield and ultimate limit states for adequately confined rectangular reinforced concrete structural walls in terms of drift ratio, plastic rotation, and curvature. To investigate the deformation limits of structural walls, a parametric study on isolated cantilever wall models is performed. The primary variables of the parametric study are the shear-span-to-wall-length ratio, wall length, axial load ratio, normalized shear stress, the amount of horizontal web reinforcement, and the amount of longitudinal reinforcement at the confined boundary of structural wall models. Expressions and limit values are proposed for yield and ultimate deformation capacity of structural walls, based on the most influential parameters. The proposed equations are found to be promising when compared to results of experiments.

Performance limits for structural walls: An analytical perspective

Recently proposed changes to modeling and acceptance criteria in seismic regulations for both flexure and shear dominated reinforced concrete structural walls suggest that a comprehensive examination is required for improved limit state definitions and their corresponding values. This study utilizes nonlinear finite element analysis to investigate the deformation measures defined in terms of plastic rotations and local concrete and steel strains at the extreme fiber of rectangular structural walls. Response of finite elements models were calculated by pushover analysis. We compare requirements in ASCE/SEI 41, Eurocode 8 (EC8-3) and the Turkish Seismic Code (TSC-07). It is concluded that the performance limits must be refined by introducing additional parameters. ASCE/SEI 41 limits are observed to be the most accurate yielding conservative results at all levels except low axial load levels. It is shown that neither EC8-3 nor TSC-07 specifies consistent deformation limits. TSC-07 suggests unconservative limits at all performance levels, and it appears to fall short of capturing the variation reflected in the calculated values. Likewise EC8-3 seems to fail to represent the variation in plastic rotation in contrast to several parameters employed in the calculation. More accurate plastic rotation limits are proposed.

Earthquake response of slender planar concrete walls with modern detailing

Reinforced concrete structural walls are used commonly as the primary lateral-load resisting system in buildings. The research presented here represents the results of the first phase of a multi-year research effort aimed at developing tools to enable performance-based earthquake engineering (PBEE) of structural walls. The first phase of the research effort focused on the seismic behavior and analysis of slender planar walls and included laboratory testing of four planar wall sub-assemblages. The walls simulated the bottom three stories of a 10-story prototype building; loading apparatus available at the University of Illinois, Network for Earthquake Engineering Simulation laboratory were used to simulate the load demands, permitting maximum test-specimen scale and realistic demand patterns. The walls were detailed to modern code requirements and standard practice and included heavily reinforced boundary elements. The test matrix studied the effects of reinforcement layout, shear demand, and lap splices at the base of the wall. All of the walls exhibited damage in the compression region, even at relatively low drifts. The splice affected the location of the damage. Walls without splices sustained damage at the base of the wall; walls with splices sustained damage at both the top of the splice and the base of the wall, with the critical region depending on the shear demand. Shear demand also affected response; a moderate increase in shear demand resulted in the failure mechanism changing from bar fracture to flexure–compression failure of the boundary elements.

Study on Restoring Force Models of Steel High Performance Concrete Composite Structural Wall

Steel high performance concrete (SHPC) structural wall was a combination of steel and high performance concrete. They can give full play to the advantages of steel and high performance concrete and have better dynamic behavior. Several specimens of SHPC structural walls with different parameters were tested under constant axial loading and horizontal cyclic loading. The testing phenomena and failure mechanics of those walls were compared and analyzed. On the basis of theoretic formulas and testing data, the main characteristic points and the law of stiffness degradation were presented, then, the tri-linear and four linear restoring models were built and provided. At last, the calculation formulas of stiffness parameter in restoring force model at different stages of deformation were presented. The results show that the declined strength stage of skeleton curve of specimens is related to the yielding strain of boundary steel, axial load ratio and stirrup content. The restoring force model of SHPC structural wall is thus formed for the application of nonlinear dynamics analysis as well as static structural calculations.

The Collapse of the Alto Río Building during the 27 February 2010 Maule, Chile, Earthquake

The Alto Río Building, a 15-story building located in Concepción, Chile, collapsed during the 2010 Maule earthquake. Construction of the building was completed in 2009 following the Chilean building code of 1996. The building was provided with reinforced concrete structural walls (occupying nearly 7% of the floor area) to resist lateral and vertical loads. The walls failed in the first story, causing the overturning of the entire building. This paper provides detailed field observations and discusses plausible causes of the collapse.

Cumulative Damage Investigation of Research Status and Problem Analysis of RC Structure

Reinforced concrete (RC) structural walls are one of the most commonly used lateral load resisting systems for high-rise buildings in strong seismic regions because of its good lateral resistance. Serious damage occurs when RC structure subjected to strong seismic action. Classified and brief comment of documents concerning damage indices and its calculation methods are conducted. It could be concluded that most of the damage evaluative models can not directly consider the effect of cumulative damage of material to mechanical properties of structure. Suggestions are proposed to improve the accuracy in damage evaluation of RC structure.

Response Spectrum Analysis of Reinforced Concrete Buildings

In this work, a parametric study on reinforced concrete (RC) structural walls and moment resisting frames building representative of structural types using response spectrum method is carried out. Here, the design spectra recommended by Indian Standard Code [1] and two other well known codes (Uniform Building Code, Euro Code 8) have been considered for comparison. The main objective of this study is to investigate the differences caused by the use of different codes in the dynamic analysis of multistoried RC building. Three different floor plans that are symmetric (SB), monosymmetric (MB), and unsymmetric (UB) with torsional irregularity are taken as sample buildings. To evaluate the seismic response of the buildings, elastic analysis was performed by using response spectrum method using the computer program SAP2000. Periods, base shears, lateral displacement and interstory drift, torque located at code defined ground type are comparatively presented. It is observed from the comparative study that the base shear using IS code is higher in all the three buildings, when compared to that of with other codes.

Deformation-Based Nonlinear Finite Element Analysis of Steel High Performance Concrete Structural Walls

Base on the experiment results of steel high performance reinforced concrete (SHPRC) structural walls, nonlinear finite element(FE) analysis is performed to simulate the complete process of the loading and concrete crack of SHPRC structural walls in the platform of ABAQUS. The nonlinear of material is taken into account in the models. The reliability of the finite element model is verified through the comparison of the analysis results and the experimental results. Based on the proposed model, the parametric analysis is carried out to study the effect of axial load ratio, aspect ratio, stirrup characteristic value, and steel ratio on the seismic behavior of SHPRC structural walls. It is concluded that the bearing capacity of SHPRC structural walls increase with the increase of the axial load ratio, but the deformation decreases obviously. The deformation and bearing capacity of the structural walls are improved by increasing the steel ratio. With increasing the stirrup characteristic value, the deformation of the structural walls improves significantly. The stirrup characteristic values are proposed to ensure the SHPRC structural walls for different axial load ratios meet the deformation capacity of drift ratio of 1/120,1/100 and 1/80, respectively.

Computer Simulation and Energy-Saving Analysis of a Composite Steel Residential Building

The steel frame-reinforced concrete core wall structure is a typical composite structure, which has been applied to residential buildings for its excellent seismic behavior. In order to evaluate the energy consumption of existing residential buildings with composite structures, an on-site test on envelope of a typical composite steel residential building in cold region is performed; the heat transfer coefficient K of envelope and its actual energy consumption are calculated and analyzed by use of the testing data. Based on that, a simplified computer model is established and verified. Parameter analyses are carried out on two main influential factors. The results indicate that the building envelope has good heat storage property and it could keep indoor thermal stability; the steel frames and windows have heat bridge effects ； the tested building only meet requirements of energy-saving 50%-standard, instead of 65%-standard; the traditional calculation method for energy consumption overestimates the energy consumption of buildings; the most effective way to reduce heating consumption is to improve thermal performances of external walls; the thickness of insulation layers should be confined in an appropriate range. Finally the thermal design recommendations for composite steel residential buildings are proposed.

Effective Stiffness of Squat Structural Walls

Reinforced concrete (RC) structural walls are the primary lateral-load carrying elements in many structures designed to resist earthquakes. A review of the technical literature shows considerable uncertainty with regards to the effective stiffness of these structures when subjected to seismic excitations, which many design practices currently deal with by employing a stiffness reduction factor. In an attempt to obtain additional information regarding the stiffness of these structures, an analytical approach, combining the flexure and shear components of deformation, is proposed to evaluate the effective stiffness of the RC walls tested. Based on this proposed analytical approach, a comprehensive parametric study comprising 180 combinations was carried out and a simple equation for assessing effective stiffness of RC squat structural walls then proposed, on the basis of these parametric case studies.

A New Rule-Based Strategy to Determine The Failure modes of Structural Walls

Parameters affecting types of failure of reinforced concrete structural walls with arbitrary aspect ratios and cross section are investigated using data from numerous wall tests. Basically there are three known primary failure modes that covers prominent behavior of wall at the failure load. Shear failure is known by diagonal tension cracks and premature yielding of shear reinforcement that leads to abrupt none-ductile failure. To insure a ductile flexural failure, it is recommended that strength in shear be equal or grater than strength in flexure. Flexural-shear failure is another type of failure that needs to more details to identify explicitly and it is divided to two different cases namely web crushing or sliding shear failure. A new model is proposed to predict the failure modes of structural walls in terms of shear strength, nominal shear stress, shear force related to flexural capacity, the level of compression in concrete and control of sliding shear failure.

Lattice Concrete Wall Structure Optimization and Numerical Analysis

Polystyrene formwork of lattice concrete wall is a set of lightweight, insulation, sound insulation, fireproof, bearing multi-function in one of the "EPS new energy-saving" wall structure system. Through the polystyrene formwork structure forms of optimized improvement built in construction process of collapse produced high wall plate phenomenon. Do an axial compression ratio of 0.2 lattice specimens of reinforced concrete shear wall in axis pressure and reciprocating level forces test. The damage form of that wall for wall bottom beam-column central cross core ring crack and appear "X" type crack and are crushed. The mesh wall formed strong vertical limb and weak horizontal limb，belongs to the ductility structure , and has more yield , and energy dissipation capacity , and wall overall performance is strong , and avoid brittle failure , and has good ductility、deformation ability and bearing capacity of the characteristics of big .The finite element analysis and experimental results indicated that the ultimate bearing capacity of the wall are the same. For new formworks do wall by finite element analysis, in do not affect its aseismic capacity premise that wall structure forms are optimized design.

Nonlinear behavior of composite shear walls with vertical steel encased profiles

Research on seismic engineering of buildings using composite steel–concrete structural systems has increased in the past decade. One horizontal resisting system for buildings, placed in seismic areas, is the composite steel–concrete structural shear wall with steel encased profiles (CSRCW). The benefits of this structural system, relative to more common systems, include the performance characteristics when subjected to service or ultimate loads. The present paper summarizes the experimental results of recent research made on six experimental steel–concrete composite elements 1:3 scale, tested in laboratory under cyclic lateral loads. The experimental elements differ by the arrangement of the steel shapes embedded in the cross section of the wall and by the cross section type of the steel encased profiles. All specimens were tested under constant vertical load and cyclically increasing horizontal (lateral) loads. The tests were performed until failure. Using the recorded data during the tests, the following parameters are presented and discussed: maximum load capacity, stress and strain distribution in structural components (reinforcements, structural steel and on concrete surface), interstory drifts, cracking patterns, deformation and degradation capacity.

Seismic Performance Analysis of Steel Reinforced Concrete Frame-Concrete Core Wall Structure

A steel reinforced concrete frame-concrete core wall structure is taken as the research object in this paper. The whole space finite element models are established by software ETABS, modal analysis, response spectrum method and elastic time-history analysis are conducted. And static elastio-plastic time history analysis of the high-rise structure is conducted by software MIDAS/GEN. Seismic response of the high-rise structure is analyzed under medium earthquake and rare earthquake , elastic deformation is calculated under conventional earthquake and elastic-plastic deformation is calculated under rare earthquake. The results show that the structure can meet the requirements of no-damage under light earthquake, repairable under medium earthquake and no-collapse under strong earthquake.

Multi-Objective Optimization Design of Hybrid Structure

The primary goal of failure modes-based optimization design which is to study the performance of structure without shocking absorption device is to transform the non-ideal failure modes of structure into the ideal failure modes, and then a small probability of the structure damage can be obtained. Although the study of this field is significant, no paper has so far attempted to study. Taking the cost of the structure into consideration, this paper aims at the failure modes-based optimization design. Therefore, an optimal approach based on failure modes with the ability to limit the cost is proposed. The procedure to obtain the failure modes-based optimization includes two phases, the concrete optimization and the shaped steel optimization. At last a reinforced concrete frame-shear wall structure is cited to verify the method developed. It is concluded that the method can supply an effective way to reduce both the damage and the cost of steel reinforced concrete framework-core tube structure.

Direct Strut-and-Tie Model for Ultimate Shear Strength of Reinforced Concrete Structural Walls

A direct strut-and-tie model to calculate the ultimate shear strength of structural walls based on an interactive mechanical model (C.Y.Tang et al.) is presented. Two common failure modes, namely, diagonal splitting and concrete crushing, are examined in this paper. Ultimate shear strengths of structural walls are governed by both the transverse tensile stresses perpendicular to the diagonal strut, and the compressive stresses in the diagonal strut. Such proposed model is verified aganist three experimental case studies of structural walls. Generally, predictions by the proposed model are not only accurate and consistent in each case study, but also conservative.