钢板剪力墙结构基本自振周期简化计算研究

本文针对钢板剪力墙结构自振周期缺乏研究的现状,将钢板剪力墙简化为Timoshenko梁,提出了考虑周边框架影响的钢板剪力墙等效抗剪刚度计算的方法,然后根据Southwell-Dunkerley理论,给出了钢板剪力墙结构基本自振周期的简化计算公式。然后,通过56个算例比较分析了本文公式计算结果与有限元计算结果发现:本文公式计算结果与有限元结果之比的平均值为1.015,标准差为0.049,说明本文公式具有足够的可靠性。接着,又对结构高度、均布质量、等效抗剪、抗弯刚度、钢板的高厚比、高宽比等参数进行了分析,分析结果表明:随着结构高度与均布质量开方的乘积增大,结构的基本自振周期增长;层数相同时,随着等效抗剪刚度、抗弯刚度的增大,周期有减小的趋势;层数相同时,随着钢板高厚比与高宽比乘积的增大,周期增长。     

Seismic demand sensitivity of reinforced concrete shear‐wall building using FOSM method

The uncertainty in the seismic demand of a structure (referred to as the engineering demand parameter, EDP) needs to be properly characterized in performance‐based earthquake engineering. Uncertainties in the ground motion and in structural properties are responsible for EDP uncertainty. In this study, sensitivity of EDPs to major uncertain variables is investigated using the first‐order second‐moment method for a case study building. This method is shown to be simple and efficient for estimating the sensitivity of seismic demand. The EDP uncertainty induced by each uncertain variable is used to determine which variables are most significant. Results show that the uncertainties in ground motion are more significant for global EDPs, namely peak roof acceleration and displacement, and maximum inter‐storey drift ratio, than those in structural properties. Uncertainty in the intensity measure (IM) of ground motion is the dominant variable for uncertainties in local EDPs such as the curvature demand at critical cross‐sections. Conditional sensitivity of global and local EDPs given IM is also estimated. It is observed that the combined effect of uncertainties in structural properties is more significant than uncertainty in ground motion profile at lower IM levels, while the opposite is true at higher IM levels. Copyright © 2005 John Wiley & Sons, Ltd.     

Inelastic earthquake response of single‐story asymmetric buildings: an assessment of simplified shear‐beam models

The inelastic seismic torsional response of simple structures is examined by means of shear‐beam type models as well as with plastic hinge idealization of one‐story buildings. Using mean values of ductility factors, obtained for groups of ten earthquake motions, as the basic index of post‐elastic response, the following topics are examined with the shear‐beam type model: mass eccentric versus stiffness eccentric systems, effects of different types of motions and effects of double eccentricities. Subsequently, comparisons are made with results obtained using a more realistic, plastic hinge type model of single‐story reinforced concrete frame buildings designed according to a modern Code. The consequences of designing for different levels of accidental eccentricity are also examined for the aforementioned frame buildings. Copyright © 2003 John Wiley & Sons, Ltd.     

Coupled shear‐bending formulation for seismic analysis of stacked wood shear wall systems

A summary of the development of a new coupled shear‐bending model for analysis of stacked wood shear walls and multi‐story wood‐frame buildings is presented in this paper. The model focuses on dynamic response of light‐frame wood structures under seismic excitation. The formulation is intended to provide a more versatile option than present pure shear models in that the new model is capable of accurately capturing the overall lateral response of each story diaphragm and separates the inter‐story shear deformation and the deformation associated with rotation of the diaphragm due to rod elongation, which is an analogue to the bending deformation in an Euler–Bernoulli beam model. Modeling the coupling of bending and shear deformation is shown to provide more accurate representation of stacked shear wall system behavior than a pure shear model, particularly for the upper stories in the assembly. The formulation is coupled with the newly developed evolutionary parameter hysteretic model for wood shear walls. Existing data from a shake table test of an isolated three‐story wood shear wall were used to verify the accuracy of the model prediction. The numerical results agreed very well with shake table test measurements. The influence of a continuous rod hold‐down system on the dynamic behavior of the three‐story stacked wood shear wall was also successfully simulated. Copyright © 2009 John Wiley & Sons, Ltd.     

Seismic performance of a 1 : 15‐scale 25‐story RC flat‐plate core‐wall building model

Earthquake simulation tests were conducted on a 1 : 15‐scale 25‐story building model to verify the seismic performance of high‐rise reinforced‐concrete flat‐plate core‐wall building structures designed per the recent seismic code KBC 2009 or IBC 2006. The following conclusions can be drawn from the test results: (1) The vertical distribution of acceleration during the table excitations revealed the effect of the higher modes, whereas free vibration after the termination of the table excitations was governed by the first mode. The maximum values of base shear and roof drift during the free vibration are either similar to or larger than the values of the maximum responses during the table excitation. (2) With a maximum roof drift ratio of 0.7% under the maximum considered earthquake in Korea, the lateral stiffness degraded to approximately 50% of the initial stiffness. (3) The crack modes appear to be a combination of flexure and shear in the slab around the peripheral columns and in the coupling beam. Energy dissipation via inelastic deformation was predominant during free vibration after the termination of table excitation rather than during table excitation. Finally, (4) the walls with special boundary elements in the first story did not exhibit any significant inelastic behavior, with a maximum curvature of only 21% of the ultimate curvature, corresponding to an ultimate concrete compressive strain of 0.00638 m/m intended in the displacement‐based design approach. Copyright © 2014 John Wiley & Sons, Ltd.     

高层建筑转换梁上短肢剪力墙抗震试验和分析

本文依据实际工程的背景,通过高层建筑转换梁上的两个短肢剪力墙试件的拟静力试验,研究其破坏模式,抗震性能和计算方法。在试验研究的基础上,采用非线性有限元方法进行分析计算,为解决实际的复杂体型高层建筑抗震设计提供一些建议。     

Estimation of monotonic behavior of reinforced concrete columns considering shear‐flexure‐axial load interaction

Reinforced concrete columns with insufficient transverse reinforcement and non‐seismic reinforcement details are vulnerable to brittle shear failure and to loss of axial load carrying capacity in the event of a strong earthquake. In this paper, a procedure is presented after examining the application of two macro models for displacement‐based analysis of reinforced concrete columns subjected to lateral loads. In the proposed model, lateral load‐deformation response of the column is simulated by estimating flexural and shear deformation components separately while considering their interaction and then combining these together according to a set of rules depending upon column's yield, flexural and shear strengths. In addition, lateral deformation caused by reinforcement slip in beam–column joint regions and buckling of compression bars are taken into account and considered in the analysis. Implementation of the proposed procedure produces satisfactory lateral load–displacement relationships, which are comparable with experimental data. Copyright © 2012 John Wiley & Sons, Ltd.     

Failure simulation of shear‐critical RC columns with non‐ductile detailing under lateral load

Reinforced concrete columns with non‐ductile detailing typically exhibit a softening behavior characterized by severe degradation when subjected to cyclic lateral loads. Whether the response is brittle or ductile, shear failure occurs with an inclined through crack along which sliding occurs coupled with loss of horizontal and vertical load‐bearing capacity of the member. The rapid loss of resistance after the peak strength is reached is because of one or more of the following local failure mechanisms: brittle failure of poorly confined concrete; buckling of longitudinal reinforcing bars because of lack of adequate transverse reinforcement or following opening of stirrups after spalling of cover concrete; bond failure. In this study, a modeling strategy to build a detailed 3D finite element model capable of capturing all of the above‐mentioned local failure mechanisms is presented. In particular, a steel–concrete interface model for representing the interaction within the member between concrete core, cover and longitudinal and transverse reinforcement is proposed. Comparison with results of an experimental test of a shear‐sensitive column demonstrates the effectiveness of the simulation up to failure of the element. Copyright © 2016 John Wiley & Sons, Ltd.     

Flexural–torsional behaviour of steel reinforced concrete members subjected to repeated loading

This paper presents an experimental investigation of the inelastic behaviour of steel reinforced concrete (SRC) members under cyclically applied bending and torsional loading. Fourteen steel reinforced concrete members made from three structural‐steel sections with different cross‐sectional properties were tested under various combinations of bending and torsion. Results indicate that the ultimate flexural capacity of an SRC member was significantly reduced under a moderate degree of torsion. Based on these findings, a quantitative evaluation of the effect of torsion was made and a simplified interaction curve between bending and torsion is proposed. Copyright © 2000 John Wiley & Sons, Ltd.     

RC剪力墙结构小震与中震设计对比及其抗震性能研究

近年来,国内学者强调对于复杂和超限结构需进行中震性能设计,即在小震弹性设计后进行中震下的承载力复核及调整,然而中震设计能否提高结构整体抗震性能仍存在争议.为探究中震设计与小震设计方法的差异,本文依据现行规范,以设防烈度、结构高度和场地类别为变化参数,建立了48个典型RC剪力墙模型,并分别以"小震"、"高规中震"、"广东...     

Correlation of dynamic characteristics of a super‐tall building from full‐scale measurements and numerical analysis with various finite element models

The Di Wang Tower located in Shenzhen has 79 storeys and is about 325 m high. Field measurements have been conducted to investigate the dynamic characteristics of the super‐tall building. In parallel with the field measurements, seven finite element models have been established to model the multi‐outrigger‐braced tall building and to analyse the effects of various arrangements of outrigger belts and vertical bracings on the dynamic characteristics and responses of the Di Wang Tower under the design wind load and earthquake action. The distributions of shear forces in vertical structural components along the building height are also presented and discussed. The results from detailed modelling of group shear walls with several types of finite elements are addressed and compared to investigate various modelling assumptions. Finally, the performance of the finite element models is evaluated by correlating the natural frequencies and mode shapes from the numerical analysis with the finite element models and the field measurements. The results generated from this study are expected to be of interest to professionals and researchers involved with the design of tall buildings. Copyright © 2004 John Wiley & Sons, Ltd.     

Extension of the CSM‐FEMA440 to plan‐asymmetric real building structures

The capacity spectrum method (CSM) has established itself as one of the most used Nonlinear Static Procedures for the seismic assessment of structures, since its introduction in 1975, when it was first presented by Freeman. More recently, this procedure was implemented in the ATC40 guidelines and lately improved in the FEMA‐440 report. The first step of work addressed by this paper relates to the comparison between the two features of the CSM. In the second part, an extension of the FEMA‐440CSM version is proposed for plan‐asymmetric real RC building structures. The case studies under analysis are the SPEAR building—an irregular 3D structure representing typical old three‐storey buildings in the Mediterranean region, from the early 1970s—and two real Turkish buildings with five and eight storeys. The CSM‐ATC40, the CSM‐FEMA440 and the proposed extended CSM‐FEMA440 method are applied and the results obtained duly compared with nonlinear dynamicit timehistory analyses. For the latter, semi‐artificial ground motions are used to define the seismic action. Copyright © 2010 John Wiley & Sons, Ltd.     

Dynamic behavior of perimeter lateral‐system structures with flexible diaphragms

Building structures are typically designed using the assumption that the floor systems serve as a rigid diaphragm between the vertical elements of the lateral load‐resisting system. However, long‐floor span structures with perimeter lateral load‐resisting systems possess diaphragms which behave quite flexibly. The dynamic behaviour of such structures is dissimilar to the behavior expected of typical structures. This difference can lead to unexpected force and drift patterns. If force levels are sufficiently under‐estimated, inelastic diaphragm behaviour can occur, exacerbating the effects of diaphragm flexibility. Such response may lead to a non‐ductile diaphragm failure or structural instability due to high drift demands in the gravity system. Analytical models were developed which capture the diaphragm flexibility of structures with long‐floor spans and perimeter lateral‐systems. Modal examination and time‐history analyses were performed to determine the effect of diaphragm flexibility and diaphragm inelastic behaviour on the dynamic behaviour of these structures. Copyright © 2001 John Wiley & Sons, Ltd.     

Pin‐supported walls for enhancing the seismic performance of building structures

An application of a pin‐supported wall‐frame system in retrofitting an eleven‐story steel reinforced concrete frame is introduced. The retrofit aims at enhancing integrity and avoiding weak story failure in an existing moment‐resisting frame. Seismic performance of the building before and after the retrofit is assessed through nonlinear dynamic analysis. The results show that the pin‐supported walls are effective in controlling the deformation pattern of the ductile frame and hence in avoiding weak story failure. With the well‐controlled deformation pattern, carefully arranged energy dissipating devices are able to concentrate energy dissipations so that damage to the rest of the structure can be significantly reduced. Copyright © 2012 John Wiley & Sons, Ltd.     

An experimental study of a damage‐controllable plastic‐hinge‐supported wall structure

The reinforced concrete (RC) shear wall serves as one of the most important components sustaining lateral seismic forces. Although they allow advanced seismic performance to be achieved, RC shear walls are rather difficult to repair once the physical plastic hinge at the bottom part has been formed. To overcome this, a damage‐controllable plastic hinge with a large energy dissipation capacity is developed herein, in which the sectional forces are decoupled and sustained separately by different components. The components sustaining the axial and the shear forces all remain elastic even under a rarely occurred earthquake, while the bending components yield and dissipate seismic energy during a design‐level earthquake. This design makes the behavior of the system more predictable and thus more easily customizable to different performance demands. Moreover, the energy dissipation components can be conveniently replaced to fully restore the occupancy function of a building. To examine the seismic behavior of the newly developed component, 3 one third‐scale specimens were tested quasi‐statically, including 1 RC wall complying with the current design codes of China and 2 installed with the damage‐controllable plastic hinges. Each wall was designed to have the same strength. The experimental results demonstrated that the plastic‐hinge‐supported walls had a better energy dissipation capacity and damage controllability than the RC specimen. Both achieved drift ratios greater than 3% under a steadily increasing lateral force.     

Cyclic tests of four two‐story narrow steel plate shear walls. Part 2: experimental results and design implications

This paper is the second part of a two‐part paper presenting the cyclic tests of four two‐story narrow steel plate shear walls (SPSWs). The first paper introduces the analytical studies and the specimen designs. This paper describes the test results. Some design implications including the capacity design for the first story column and the width‐to‐thickness ratio check for the beam web are discussed based on key observations from the tests. Test results confirm that the simplified strip model can accurately predict the inelastic responses of the specimens. Test results also confirm that the proposed capacity design method is effective in ensuring the plastic hinge formation at the bottom end of the first story column for SPSW with or without restrainers. Test results also show that the horizontal restrainers are effective in reducing the member forces in the boundary beam and column elements. Comparing the test results of the typical SPSW with those of the restrained SPSW (R‐SPSW) specimens, it is found that the R‐SPSW possesses an improved cyclic performance and reduced material weight. Analytical results predict the compressed column moments at the onset of the column plastic hinge formation well. The analytical hysteretic energy distribution in the first story column agrees very well with the observed inelastic actions developed in the four specimens. The detailed frame response analyses and the test results confirm that the assumptions made in developing the proposed column capacity design method are reasonable. Copyright © 2009 John Wiley & Sons, Ltd.     

Seismic design and response evaluation of unbonded post‐tensioned hybrid coupled wall structures

This paper presents an analytical investigation on the seismic design and response of coupled wall structures that use unbonded post‐tensioned steel coupling beams. Both monolithic cast‐in‐place reinforced concrete wall piers and precast concrete wall piers are considered. Steel top and seat angles are used at the coupling beam ends for energy dissipation. The seismic design of prototype structures to achieve target displacement‐based performance objectives is evaluated based on nonlinear static and dynamic time history analyses. Additional recommendations are provided on shear design. Comparisons with ‘conventional’ structures that use embedded steel coupling beams as well as isolated walls with no coupling are provided. The results indicate that while the peak lateral displacements of unbonded post‐tensioned coupled wall structures are larger than the peak displacements of structures with embedded beams, the residual displacements are significantly reduced as a result of the restoring effect of the post‐tensioning steel. Copyright © 2008 John Wiley & Sons, Ltd.     

Correlating dynamic characteristics from field measurements and numerical analysis of a high‐rise building

Using the concept of lumped masses and rigid floor slabs, several mathematical models were built using a popular PC‐based finite element program to model a tall building with a frame‐core wall structural system. These models were analysed to obtain the first nine mode shapes and their natural frequencies which were compared with those from field measurements, using numerical correlation indicators. The comparison shows several factors that can have a significant effect on the analysis results. Firstly, outriggers connecting the outer framed tube system to the inner core walled tube system have a significant effect on fundamental translational mode behaviour. Secondly, detailed modelling of the core considering major and minor openings as well as internal thin walls has the strongest influence on torsional behaviour, whose measurements were shown to be an important aspect of the dynamic behaviour for the structure studied. Fine tuning of an analytical model requires not just considering variation in values of structural parameters but also attention to fine detail. Copyright © 2000 John Wiley & Sons, Ltd.