An investigation on the interaction of moment‐resisting frames and shear walls in RC dual systems using endurance time method

Reinforced concrete (RC) dual systems are composed of RC moment‐resisting frames (MRFs) and RC shear walls, where MRFs are barely designed to handle gravity loads. Investigations have demonstrated that shear walls exert negative effects on the upper part of MRFs. In this paper, the interaction of shear walls and MRFs is inspected using endurance time (ET) method. ET is a dynamic time history‐based pushover procedure in which structures are exposed to a set of predefined intensifying ET acceleration functions. In this method, seismic performance of the considered structure is assessed based on earthquake return periods; during which, required predefined seismic performance objectives are fulfilled. In this study, several buildings with RC dual systems were designed based on the conventional codes. Next, their nonlinear duplicates were generated for the application of the ET analysis. It was revealed that shear wall elements impose considerable rotational demands—exceeding the criteria established by ASCE41‐13—on the beams and columns, especially those located on the upper parts of the buildings. This paper puts forth and reviews certain methods to cushion the negative effects brought about by RC shear walls, along with a detailed discussion on their merits and demerits.     

An investigation on the behavior of stiffened coupled shear walls considering axial force effect

In most of tall buildings, the main contribution of lateral loads is carried by coupled shear walls. In some cases, the necessary stiffness to withstand the lateral load may not be afforded due to low depth of connecting beams. In order to increase the capacity of the coupled shear walls, beams with high stiffness are added to the system at particular levels. Hence, stiffened coupled shear walls (SCSW) will be produced. Such walls are under axial load resulting from their weight, and this axial load affects the behavior of walls because of their excessive height. In this paper, a new method considering the effect of axial force for geometrically nonlinear analysis of the SCSW has been presented. A computer program has been developed in matlab , and numerical examples have been solved to demonstrate the reliability of this method. The results of the examples show the agreement between the present method and the other methods given in the literature. The effects of the various positions and rigidities of the stiffening beam on the internal forces and the lateral deflection of the structure considering axial force effect have also been investigated. Copyright © 2012 John Wiley & Sons, Ltd.     

Cyclic behaviour of hinged steel frames enhanced by masonry columns and/or infill walls with/without CFRP

Abstract

This paper investigates the in-plane seismic behaviour of hinged steel frames that are enhanced with masonry columns and/or infilled walls. First, eight half-scaled hinged steel frame specimens were constructed according to the realistic structural system of Bund 18, which is a historical building in Shanghai, China. Then, cyclic loads were exerted on these frames. The test results indicated that the seismic behaviours of the hinged steel frames can be significantly improved with the use of masonry columns and/or infilled masonry walls as well as with proper strengthening due to carbon fibre-reinforced polymer (CFRP) sheets. A simplified model was developed to simulate the seismic behaviours of these frames. In this model, infilled walls and CFRP sheets were replaced by diagonal struts, and the steel members and their surrounding elements were treated as composite members. Finally, this model was verified by experimental results.     

双肢剪力墙中连梁延性的研究

对双肢剪力墙的连梁采用数学方法进行了分析,并且考虑在不同情况下连梁所需的延性。     

Seismic performance of reinforced concrete shear wall frames considering soil–foundation–structure interaction

A practical application of ‘beam on nonlinear Winkler foundation’ approach has been utilized in this paper for a case study on seismic performance of concrete shear wall frames to assess the soil–foundation–structure interaction effects. A set of 3‐, 6‐, 10‐ and 15‐story concrete shear wall frames located on hypothetically soft, medium and hard soils were designed and modeled using the OpenSees platform. The numerical model of each frame was constructed employing the distributed and lumped plasticity elements as well as the flexure–shear interaction displacement‐based beam–column elements incorporating the soil–footing interface. Pushover analysis was performed, and the results were studied through two code‐based viewpoints: (a) force‐based design and (b) performance‐based design. A comparison was made afterwards between the frame behaviors in the fixed‐/flexible‐base conditions. The results indicate some degree of inaccuracy in the fixed‐base assumption, which is regularly applied in analysis and design practice. The study emphasizes on how the fixed‐base assumption overestimates the design of the wall element and underestimates the design of the connected moment frame. Copyright © 2012 John Wiley & Sons, Ltd.     

Experimental study on the seismic behavior of a shear wall with concrete‐filled steel tubular frames and a corrugated steel plate

Shear walls and core tubes in shear walls constitute the core anti‐earthquake vertical systems of high‐rise buildings. This paper proposes a new type of composite shear wall with concrete‐filled steel tubular frames and corrugated steel plates. The seismic behavior of the new shear wall is studied using a cyclic loading test and damage analysis. The failure mode, load‐carrying capacity, ductility, stiffness degradation, hysteresis behavior, and energy dissipating capacity exhibited in the test are studied. The test results show that when the proposed wall is broken, the tension side of concrete‐filled steel tubes is torn. The concrete at the bottom of the wall is detached and peels off along the through cracks. The energy dissipation capacity of concrete walls is more fully utilized. The proposed wall exhibits excellent deformability, energy dissipation capacity, and the stiffness degradation was slower than that of other walls. The use of corrugated steel plate significantly improved the seismic performance while simultaneously increasing the ductility and reducing the damage. In addition, this paper modified the energy dissipation factor in the Park & Ang model based on the situation of the specimen and experiment. It can be used to evaluate the damage degree of this new type of shear wall.     

基坑地下连续墙渗漏水事故原因和处理措施

从三个方面分析了地下连续墙漏水的原因,通过对地下连续墙漏水案例的论述,探讨了造成基坑事故的原因,提出了相应的处理措施,总结出地下连续墙渗漏水分析中得到的启示.     

考虑上部结构共同作用的弹性地基上筏板基础分析

首先利用子结构的凝聚技术进行上部结构分析和利用有限元和边界元对Winkler地基上的筏板基础进行分析,然后通过力的平衡和位移的协调关系建立了整体耦合分析方程,并进行了算例分析。     

基于剪切位移法的长短桩复合地基沉降计算

在深入探讨长短桩复合地基作用机理基础上,针对长短桩复合地基的桩–土–承台整体相互作用特点,通过一定的简化假定,建立出长短桩复合地基的沉降计算模型;然后以剪切位移法为基础,引入Mylonakis&Gazetas桩-桩、桩-土相互作用模型,导出长短桩复合地基计算时的桩-桩、桩-土以及土-土相互作用柔度系数;在此基础上,考虑垫层作用的影响,提出一种综合考虑桩-土-垫层体系共同作用的长短桩复合地基沉降计算方法,并编制出相应的计算程序。最后利用该法对某工程实例进行了计算分析,结果表明,基于本文方法获得的沉降预测值与实测值吻合较好。     

带填充墙钢框架结构抗侧力性能试验及理论研究

介绍了7榀钢框架及带填充墙钢框架结构的水平静力及低周反复加载试验。通过测试有墙和无墙钢框架试验模型在侧向力作用下的变形全过程,得到了墙体对钢框架结构强度和刚度的影响,了解了节点的破坏特征及墙体本身的工作性能,得到了有墙及无墙钢框架结构的滞回性能。试验中发现,填充墙体和钢框架之间的连接性能很好,墙体和框架可以共同工作。通过参数分析,给出了结构抗震弹性层间角位移的建议取值为1/350。在理论分析的基础上,提出了填充墙框架体系抗侧刚度简化公式,得到了试验结果的验证。     

钢管混凝土柱-钢梁平面框架抗震性能的试验研究

为了探讨钢管混凝土柱-钢梁平面框架的抗震性能,本文进行了12个框架试件在恒定轴力和水平反复荷载作用下的试验研究,主要考察了柱截面形状(圆形、方形)、含钢率(圆形:α=0.06,0.103;方形:α=0.125,0.126)、柱轴压比(圆形:n=0.06~0.60;方形:n=0.04~0.60)、梁柱线刚度比(圆形:i=0.36~0.58;方形:i=0.34~0.62)等参数对其力学性能的影响。试验结果表明:钢管混凝土柱-钢梁框架滞回曲线较为饱满,强度和刚度退化不明显;柱轴压比和含钢率对框架的承载力和抗震性能影响较大,随着轴压比的增大,框架的水平极限承载力下降,位移延性和耗能能力降低,而含钢率影响规律则相反;圆形截面柱框架抗震性能整体上优于方形截面柱框架。按照《钢管混凝土结构技术规程》(DBJ13—51—2003)设计的钢管混凝土框架能够满足结构抗震设计要求。     

弹性基础边界基本顶薄板初次破断的kDL效应

 基本顶的初次破断规律多采用四边固支边界模型分析,但实际的岩层环境难以实现固支。为了研究基本顶实际围岩条件时的破断规律及破断条件,建立弹性基础边界条件弹性薄板力学模型,运用有限差分方法计算弹性基础系数k与基本顶厚度h、弹性模量E、泊松比、跨度L之间的相互关系对基本顶主弯矩及起始破断位置的影响,并根据主弯矩破断准则得出：弹性基础边界时基本顶首先在中部或长边超前煤壁处破断;比值k/E或k/h3或k/(Eh3)不变时基本顶破断位置不变;k/E或k/h3或k/(Eh3)小时基本顶中部先破断、即煤层松软、基本顶厚度及弹性模量大时基本顶中部先破断;k/E或k/h3或k/(Eh3)大时基本顶长边超前煤壁先破断、即煤层坚硬且基本顶厚度及弹性模量小时基本顶长边先破断。弹性基础边界时基本顶的初次破断规律由k,L和基本顶刚度D复合决定,长壁工作面基本顶的破断类型及条件为(k/D)1/4L＞9.6时：长边超前煤壁→中部→短边超前煤壁、或长边超前煤壁→短边超前煤壁→中部,(k/D)1/4L＜9.4时：中部→长边超前煤壁→短边超前煤壁,(k/D)1/4L = (9.5±0.1)时,基本顶中部和长边超前煤壁位置接近同时破断;对于方形工作面,(k/D)1/4L＞10.5时四边超前煤壁区先破断,(k/D)1/4L＜10.1时中部先破断,(k/D)1/4L = (10.3±0.2)时四边超前煤壁区与中部接近同时破断。     

含少量剪力墙RC框架结构弹性层间位移角限值研究

根据已有的试验资料并结合现有的结构设计分析方法,提出了含少量剪力墙RC框架结构的弹性层间位移角限值为1/800的参考建议。     

高层配筋砌块砌体剪力墙的延性设计研究

针对配筋砌块砌体的特点,采用数值计算的方法确定配筋砌块砌体剪力墙的屈服曲率和极限曲率,并建立剪力墙曲率延性比和位移延性比的关系。根据计算结果,讨论轴压比、剪跨比、边缘钢筋屈服强度、腹板竖向钢筋的抗力、砌体的抗压强度和极限压应变对剪力墙位移延性的影响,其中限制轴压比、设置约束边缘构件是提高剪力墙延性的有效途径。通过推导出的轴压比限值的近似公式,分析各因素对轴压比限值的影响,并建议采用约束砌块砌体和约束混凝土作为约束边缘构件以提高墙的延性。结合高层建筑工程实际,分析确定不同约束边缘构件的矩形截面和工字形截面剪力墙的轴压比限值,提出约束边缘构件的构造要求和实用的设计建议。     

Experimental evaluation of the effect of compaction near facing on the behavior of GRS walls

Experimental studies have been carried out to evaluate the effect of the compaction condition at the back of block facing on the behavior of geosynthetic reinforced soil (GRS) walls. Three GRS walls with 1.2?m high were constructed at the COPPE/UFRJ Geotechnical Laboratory. The walls were well-instrumented in order to monitor the values of the reinforcement load, toe horizontal load, horizontal facing displacement, horizontal stress at the back of the block facing, and vertical displacement on the top of the walls. The behavior of the walls has been investigated at the end of construction and during the surcharge application (post-construction). At the end of the loading, the toes of the walls were gradually released to also verify the influence of the different toe restraints. The results clearly show the effect and call attention to the importance of the compaction conditions near the facing on the behavior of GRS walls.     

The wall–frame and the steel–concrete interactions in composite shear walls

The nonlinear pushover analyses of 24 composite steel plate shear walls (CSPSWs), 24 corresponding steel plate shear walls (SPSWs), and 24 corresponding frames are conducted. CSPSWs have different aspect ratios and infill steel plate thicknesses. The study aims to understand the wall–frame and steel–concrete interactions. The infill steel plate thickness and aspect ratio of CSPSW are the main parameters of the study. In CSPSWs, the percentage of absorbed shear forces by the infill composite wall is always greater than the infill plate of its corresponding SPSW. The percentage of shear in the composite wall is constant at the initial stage of loading up to a drift of 0.15–0.2%. By increasing the drift, the shear yielding of steel plate leads to a reduction of the shear force absorption. The reduction continues until the bulk of shear stiffness of CSPSW is provided by the frame. At the beginning of lateral loading, steel–concrete interactions increase until shear yield of steel plate. Following this stage, a sudden decrease takes place in shear force absorption of reinforced concrete (RC) panel. The reason is that, at the lower drifts, the steel plate has a tendency for elastic buckling, which is prevented by the RC panel. Finally, the shear force absorption remains approximately constant in the RC panel.     

基于ANSYS的剪力墙等效刚度计算

利用商用程序ANSYS计算不同横向荷载作用下剪力墙顶点位移,从而根据设计需求计算相应荷载工况下剪力墙等效刚度,为规则和非规则开洞剪力墙的等效刚度的计算提供了一种新途径。     

考虑共同作用下的筏板基础厚度的设计方法研究

由于工程界中对于筏板基础缺少研究,不了解其具体的受力特性,在筏板基础设计方面缺乏成熟的设计理论和计算方法,筏板基础仍按常规筏基的设计方法进行设计,往往造成筏板过厚,使基础造价过高,产生很大的浪费。根据高层建筑上部结构、基础和地基共同作用的基本原理,提出一种筏板基础的计算方法,考虑了多种因素影响,比较符合基础的实际受力状况。本文研究了空间框架-筏板-地基共同作用时筏板基础的受力和变形性能,并利用有限元方法完成三维模型的数值分析。应用筏板基础的非线性分析方法,考察了影响筏板基础受力性能的混凝土强度等级、筏板基础厚度以及筏土刚度比等因素对筏板基础的受力特性的影响,通过数值计算,对筏板基础的优化设计进行了分析。通过这些结论对设计提出有利的建议,从理论上可以使筏基达到优化设计的目标,其直接结果可以使筏板减薄,降低基础造价。     

自适应控制法在桥梁施工挠度控制中的应用

结合福建省厦漳高速南港特大桥在建桥梁悬臂施工状况,重点阐述了采用挂篮平衡悬臂浇筑施工中结构预拱度设置的方法、影响挠度控制的一些主要因素,从而确保结构合龙精度和成桥后的线形。     

带边框RC低矮抗震墙实用计算方法

带边框低矮抗震墙在建筑结构设计中应用广泛,其受力性能复杂,在地震作用下一般发生剪切破坏.以试验研究及有限元分析结果为基础,分析了带边框低矮抗震墙的承载机理.利用等效斜压杆的方法,给出了无洞及开洞带周边框架RC低矮抗震墙的受剪承载力和不同受力阶段刚度的计算公式,并与试验结果进行了比较.研究结果可供设计计算时参考.