边缘配置高强纵筋装配式中高强再生混凝土剪力墙抗震性能研究#br#

为促进高性能绿色建筑结构发展,推动高强钢筋和中高强再生混凝土的工程应用,研发了边缘构件采用环筋扣合连接方式且配置高强纵筋的装配式中高强再生混凝土剪力墙,对6个剪跨比为2.2的装配式混凝土剪力墙进行了低周反复荷载试验。分析了不同再生粗骨料取代率、混凝土强度、边缘暗柱纵筋强度及搭接位置对装配式再生混凝土剪力墙的破坏形态、滞回性能、承载力、延性、刚度退化规律、耗能能力等抗震性能指标以及可恢复性能的影响。试验结果表明：边缘构件配置高强钢筋的装配式中高强再生混凝土剪力墙的破坏形态以弯曲破坏为主;再生粗骨料取代率对装配式中高强再生混凝土剪力墙的承载力、延性和耗能能力影响不大,各剪力墙均具有较好的抗震性能;边缘暗柱采用HRB600纵筋可有效提高装配式中高强再生混凝土剪力墙的承载力、耗能能力和可恢复性能;边缘暗柱纵筋在剪力墙底部塑性铰区搭接,会导致装配式中高强再生混凝土剪力墙的延性明显下降。给出了边缘配置HRB600纵筋的装配式中高强再生混凝土剪力墙水平承载力计算式,计算结果表明普通混凝土剪力墙的水平承载力计算模型同样适用于该装配式剪力墙结构。     

喷涂混凝土夹心剪力墙抗震性能试验研究及有限元分析

为研究喷涂混凝土夹心剪力墙的抗震性能,完成了7个试件的拟静力试验。试件的主要变化参数为墙厚及边缘构件。试验结果表明：夹心墙的2层或3层混凝土及其配筋可作为整体共同承担竖向压力及水平力;试件的破坏形态包括压弯破坏和剪切破坏,增加边缘构件的竖向钢筋导致试件发生剪切破坏;试件的水平力-位移滞回曲线有一定程度的捏拢;压弯破坏的试件,极限位移角为1/76~1/103,设置边缘构件的试件,其极限位移角约为没有边缘构件试件的1.3倍,增加墙厚对极限位移角影响不大;剪切破坏的试件,其耗能能力小于压弯破坏的试件;可采用剪力墙承载力公式计算夹心墙在轴压力作用下的正截面受弯承载力和斜截面受剪承载力。采用MSC. Marc（2010）对夹心墙试件进行非线性有限元分析得到了水平力-位移骨架曲线、裂缝分布及承载力,与试验结果吻合较好。     

纤维增强混凝土剪力墙抗震性能试验研究与理论分析

为根本改善混凝土基体的脆性,提高混凝土剪力墙的抗震性能和损伤容限,设计制作6个局部纤维增强混凝土（FRC）剪力墙试件,在试件变形关键部位采用FRC替代普通混凝土,并考虑高轴压比下剪力墙受压钢筋屈曲和受拉纵筋应力集中的问题,在塑性铰区纵向钢筋上设置钢套管,以改善受力钢筋的稳定性和变形性能。通过对悬臂剪力墙试件的拟静力试验,研究此类剪力墙的破坏现象、受力机理和滞回特性,探讨轴压比、FRC区高度、纵筋强度和钢套管长度等因素对墙体变形能力及耗能能力的影响。研究表明,与普通混凝土剪力墙试件相比,塑性铰区采用FRC的剪力墙试件具有较高的损伤容限和变形能力;提高钢筋强度和延性以及在纵筋上设置钢套管,对其抗震性能和耗能能力均具有明显的改善作用。     

Effect of earth reinforcement,soil properties and wall properties on bridge MSE walls

Mechanically stabilized earth (MSE) retaining walls are popular for highway bridge structures. They have precast concrete panels attached to earth reinforcement. The panels are designed to have some lateral movement. However, in some cases, excessive movement and even complete dislocation of the panels have been observed. In this study, 3-D numerical modeling involving an existing MSE wall was undertaken to investigate various wall parameters. The effects of pore pressure, soil cohesion, earth reinforcement type and length, breakage/slippage of reinforcement and concrete strength, were examined. Results showed that the wall movement is affected by soil pore pressure and reinforcement integrity and length, and unaffected by concrete strength. Soil cohesion has a minor effect, while the movement increased by 13–20 mm for flexible geogrid reinforced walls compared with the steel grid walls. The steel grid stresses were below yielding, while the geogrid experienced significant stresses without rupture. Geogrid reinforcement may be used taking account of slippage resistance and wall movement. If steel grid is used, non-cohesive soil is recommended to minimize corrosion. Proper soil drainage is important for control of pore pressure.     

火灾下钢筋混凝土墙计算模型及影响因素分析

采用有限元软件ABAQUS对火灾下钢筋混凝土墙的变形全过程进行了计算,计算结果与以往实验结果吻合较好.在此基础上,系统分析了轴压比、侧向荷载比、高厚比、墙厚度、混凝土抗压强度、钢筋屈服强度、配筋率和混凝土保护层厚度对钢筋混凝土墙变形和耐火极限的影响规律.研究结果表明,受火过程中,钢筋混凝土墙在无侧向荷载且轴压比或墙厚度...     

Flexural ductility and deformability of concrete beams incorporating high‐performance materials

High‐performance materials, such as high‐strength concrete (HSC) and high‐strength steel (HSS), are often adopted in tall buildings to reduce member size and save space. The use of HSC and/or HSS can significantly increase the flexural strength of concrete members but may also adversely affect the flexural ductility and deformability. Herein, the pros and cons of using HSC and HSS in concrete beams are investigated in terms of the limits of flexural strength, ductility and deformability that can be simultaneously achieved using nonlinear moment‐curvature analysis with stress‐path dependence of the reinforcement taken into account. The results reveal that the use of HSC or both HSC and HSS in concrete beams can at the same strength increase the ductility and deformability, or increase the strength without depleting the ductility and deformability. However, the use of HSS has no such benefit, albeit it can reduce the steel area required. Copyright © 2010 John Wiley & Sons, Ltd.     

New improved metaheuristic approaches for optimum design of posttensioned axially symmetric cylindrical reinforced concrete walls

Two novel hybrid approaches are presented for optimum design of axially symmetric cylindrical walls subjected to posttensioning loads using metaheuristic algorithms such as harmony search (HS), flower pollination algorithm (FPA), and teaching learning based optimization (TLBO). The objective function of the optimization problem is to minimize the total cost of the wall subjected to constraints on the basis of sectional capacities (bending moment, shear force, and axial tension), ACI 318 (building code requirements for structural concrete) requirements and design variables such as wall thickness, compressive strength of concrete, location and intensities of posttensioning cables, size, and spacing of reinforcement. In the optimum design, the performance of the iterative population based metaheuristic algorithms, HS, FPA, and TLBO are compared and tested by taking wall thickness as discrete and continuous variable. In order to improve the efficiency on finding global optimum results, hybrid forms of the HS combined with FPA and TLBO are effective for the optimization problem.     

预制混凝土空心模剪力墙受弯性能试验研究

进行了1片钢筋混凝土剪力墙和3片预制混凝土空心模剪力墙的拟静力试验,研究了预制混凝土空心模剪力墙的受弯性能和水平接缝的性能。结果表明,空心模剪力墙的破坏过程和破坏形态与钢筋混凝土剪力墙相似,受弯承载力基本相当;空心模剪力墙位移延性系数为6.26~7.71,破坏位移角为1/71~1/53,具有良好的变形能力。空心模剪力墙底部水平接缝处的滑移小于钢筋混凝土剪力墙,在总水平位移中所占比例小于10%,水平接缝构造合理,能够保证竖向装配单元间的有效连接,可用于实际工程。提高约束边缘纵筋配筋率和轴压比可提高空心模剪力墙的受弯承载力及刚度,改善水平接缝抵抗滑移的性能。     

榫卯式接缝预制混凝土剪力墙受力性能试验研究

为研究榫卯式接缝预制混凝土剪力墙的受力性能,进行了1片现浇钢筋混凝土剪力墙和4片预制混凝土剪力墙在恒定轴力作用下的拟静力试验,分析了榫卯式接缝性能及墙体的抗震性能。结果表明：峰值荷载前,同一位置榫卯式接缝两侧水平钢筋应变基本相同,接缝两侧墙体基本无相对变形。破坏时水平、竖向相对变形仅为0.34、0.79mm,接缝连接可靠,保证了墙体的整体性能。榫卯式接缝预制混凝土剪力墙的受弯承载力、刚度与钢筋混凝土剪力墙基本相当,能够达到“等同现浇”的设计目标;破坏时墙体竖向接缝处混凝土剥落,减小了根部混凝土压溃区域面积,提高了墙体的变形能力;当顶点位移角为1/50时,预制混凝土剪力墙仍保持良好的竖向承载能力;提高边缘构件纵筋配筋率,墙体承载力提高,破坏区域更加集中在墙体的接缝处,延缓了根部混凝土的压溃。     

页岩陶粒混凝土剪力墙抗震性能试验研究

通过5个不同高宽比、不同腹板配筋率的页岩陶粒混凝土剪力墙试件的低周反复荷载试验,研究页岩陶粒混凝土剪力墙的抗震性能及受力机理,分析页岩陶粒混凝土剪力墙破坏形态、滞回曲线、承载力、延性、耗能、刚度等。研究结果表明：页岩陶粒混凝土剪力墙具有较好的延性和受力性能;影响墙体破坏形态的主要因素是高宽比,其破坏形态与普通混凝土剪力墙及其它轻骨料混凝土剪力墙基本相似,破坏区域主要集中在距墙底墙肢宽度范围内;增大竖向配筋率有利于改善墙体的变形性能及提高墙体的承载能力;增加横向钢筋配筋率,墙体承载力并非呈比例增加。基于比拟桁架模型理论,考虑竖向分布钢筋的销栓作用,建立了页岩陶粒混凝土剪力墙斜截面承载力计算式,计算结果与试验结果吻合较好。     

钢-混凝土组合框架-核心筒结构设计研究

本文介绍了8度抗震设防区的北京LG大厦塔楼钢-混凝土组合框架-核心筒结构的设计研究和相应的节点构造。核心筒是整个结构的主要抗侧力构件,为了改善核心筒剪力墙的延性,设计中在核心筒四大角及纵横墙交点处设置钢骨柱。同时,为了提高承托楼面桁架的剪力墙联系梁的非弹性变形能力,沿核心筒y向联系梁内设置了型钢,与钢骨柱组成暗框架,加强了核心筒的整体性。弹塑性动力时程分析结果表明了这种结构体系具有较好的抗震性能,计算结果与模型的振动台试验结果非常吻合。振动台试验结果表明,在8度罕遇地震作用下,核心筒边缘构件和底部框架柱均没有发现钢筋压屈、混凝土崩落现象;核心筒与外围框架两者间能很好地协同工作;核心筒内的暗钢柱提高了楼面钢梁端部锚固能力,钢梁与混凝土墙之间的连接没有发现破坏现象,但值得注意的是梁端测得的应变较大,这种现象反映了梁(桁架)的端部即便是接“铰接”处理,仍然存在地震作用产生的约束弯矩,设计中应给予足够的重视。计算分析和试     

Performance of prefabricated high strength welded wire grids in ductile concrete shear wall boundary elements

The performance of a new proprietary concrete reinforcement product, BauMesh, when used as confinement reinforcement in ductile concrete shear walls is discussed. Large material and labor savings are achieved when concrete shear walls are reinforced with these new high strength welded wire ladders positioned at close spacing (3 o.c.) along the length of the longitudinal reinforcement to ensure a non-brittle ductile response to violent earthquake generated cyclic forces. Design, quality control during manufacture, installation, and the observed performance of a 17-story San Francisco ductile shear wall building during the Loma Prieta earthquake are discussed.     

Modelling criteria for r/c elements constructed with ultra‐high‐strength concrete and subjected to cyclic loading

High‐strength concrete (HSC) has several benefits in high‐rise concrete buildings; however, its structural use in active seismic regions may be questioned due to the lower ductility of such concretes. In addition, seismic macro‐models being used currently are based on R/C elements constructed with normal‐strength concretes (f ≤ 40 MPa (5.8 ksi)). In this paper, the performance of plastic hinges in flexural elements constructed with a concrete strength up to 175 MPa (25.4 ksi) is investigated. In addition, other variables were studied such as the sectional reinforcement asymmetry, hinge shear strength and hinge shear demand. The seismic performance is presented in terms of stiffness deterioration, strength degradation, pinching phenomenon and displacement ductility. The requirements to implement the use of HSC in current macro‐models are examined. Current hysteretic models may be used to evaluate structural components constructed with higher concrete strength; however, the influence of concrete strength is controlled by the other test variables. Copyright © 2009 John Wiley & Sons, Ltd.     

低轴压比下预制边缘构件双面叠合剪力墙抗震性能试验研究

预制边缘构件双面叠合剪力墙是一种预制率更高的装配式剪力墙,针对底部拼缝处变形集中问题,通过1个设计轴压比0.2的预制约束边缘构件与2个设计轴压比0.1的预制构造边缘构件的双面叠合剪力墙高墙足尺(高宽比为2.0)的低周水平往复加载试验,分析轴压比、边缘构件形式与底部搭接区纵筋插筋面积增加率(0%、25%与33%)对该类剪力墙抗震性能的影响。试验结果表明：剪力墙均发生了预期的弯曲破坏模式,增加插筋面积的2个双面叠合剪力墙弯剪裂缝分布更加均匀,实现了墙体损伤区由墙底水平接缝区向钢筋搭接区上部的转移,可以有效控制底部接缝区的变形与墙体损伤集中问题;滞回曲线均较饱满,增加插筋面积后剪力墙滞回环更为饱满,刚度退化减缓,耗能能力强;受弯承载力实测值为预测值的1.06~1.21倍,插筋面积增加33%的剪力墙峰值荷载提高了12%;增加插筋面积后,当剪力墙达到峰值荷载时,位移角约为1/80,而未增加插筋面积剪力墙的相应位移角约为1/140,极限位移角均大于1/70,满足我国设计规范中罕遇地震作用下剪力墙的变形能力要求。     

大剪跨比预制空心板剪力墙抗震性能试验研究#br#

预制空心板剪力墙结构是一种新型装配式剪力墙结构。为研究预制空心板剪力墙的抗震性能、同层相邻预制空心板的整体性、采用水平插筋间接搭接连接的水平钢筋的抗剪作用、灌孔边缘构件的有效性,完成了6个轴压比设计值为0.3、剪跨比为1.61~2.42、压弯破坏为主的空心板剪力墙试件的拟静力试验。试验结果表明：试件的破坏形态均为压弯破坏,实现了预期的强剪弱弯设计目标,水平钢筋能有效抵抗水平剪力;试件的水平力-位移滞回曲线比较饱满,极限位移角为1/72~1/38,可按现浇剪力墙计算偏心受压空心板剪力墙的受压承载力;同层相邻空心板之间竖向接缝的开裂宽度小,接缝两侧构件竖向错动小,斜裂缝在竖向接缝处连续,直接拼接连接、后浇竖向拼缝连接都能使空心板成为整体;采用灌孔边缘构件的空心板剪力墙,其抗震性能满足现行规范要求。     

保温砌模混凝土网格墙抗震性能试验研究

介绍了8片剪跨比为1.96～3.06的保温砌模混凝土网格墙和1片实体墙在轴力和往复水平力作用下的试验,以及3片网格墙的轴压试验。结果表明,剪跨比较大的保温砌模网格墙在轴力和往复水平力共同作用下,墙端纵筋受拉屈服,边缘混凝土压碎,墙的中下部连梁剪切破坏;破坏时裂缝较分散;极限位移角大于1/100,位移延性系数大于3;截面长的网格墙的弹性刚度、屈服时的割线刚度和正截面承载力大,墙端组合柱对提高刚度和正截面承载力有显著作用;一般层高的网格墙在重力荷载作用下不会发生平面外失稳破坏。有限元计算表明,网格墙在轴力和水平力作用下的正应力分布与实体墙总体上一致;可按现行规范有地震作用组合的剪力墙正截面承载力公式计算网格墙的承载力。工程算例表明,保温砌模现浇承重墙体系可以满足8度抗震设防的9层住宅承载力要求和抗震墙结构小震时的层间位移角要求。在研究的基础上,提出了保温砌模现浇承重墙体系的抗震设计建议。     

Fire Resistance and Post-fire Seismic Behavior of High Strength Concrete Shear Walls

In this study, both fire tests and low-frequency cyclic loading tests after fire were conducted on three conventional high strength concrete (HSC) shear walls and a superimposed HSC shear wall with precast recycled aggregate concrete (RAC) panels. The RAC in this paper was made with recycled concrete aggregate. When specimens suffered the fire exposure on one side for 45 min, 90 min, and 135 min separately, spalling of concrete, temperature distribution and deformation of specimens were investigated as indicators of fire response. When specimens were subjected to cyclic load after fire, hysteresis curves were obtained, based on which the secant stiffness degradation and energy dissipation capacity of walls were analyzed. The results indicated that HSC would suffer severe spalling during the fire and that fire response of the superimposed wall including spalling was smaller than that of conventional walls. Using RAC panel as a thermal barrier was found to be effective to alleviate spalling, as it reduced more than 60% of spalling of HSC compared with bare walls. Based on the seismic tests results, the fire exposure deteriorated the load bearing capacity, lateral stiffness and energy dissipation capacity of walls, whereas the application of RAC panels improved the load bearing capacity by about 10% even when the superimposed wall was exposed to the fire for a long time.     

高配筋率边缘约束构件高强混凝土剪力墙抗震性能试验研究

为改善高强混凝土剪力墙的延性,设计了7个不同形式的高配筋率边缘约束构件高强混凝土剪力墙试件（边缘约束构件内的纵筋配筋率约为5%~8%）和1个普通配筋率的高强混凝土剪力墙试件,对其进行低周反复水平荷载作用下的拟静力试验,研究了剪力墙试件的破坏形态、滞回特性、变形能力、截面应变、刚度退化、耗能能力等。试验结果表明：对于剪跨比λ≥2的剪力墙,在高强混凝土剪力墙中设置高配筋率暗柱或端柱,并适当提高水平和竖向分布钢筋的配筋率,可以显著提高高强混凝土剪力墙的抗震性能。     

Experimental assessment of the seismic performance of a prefabricated concrete structural wall system

In this study the authors investigated experimentally the behaviour of prefabricated reinforced concrete sandwich panels (RCSPs) under simulated seismic loading through a large experimental campaign. Tests were carried out on single full-scale panels with or without openings, simulating the behaviour of lateral resisting cantilever and fixed-end walls. Tests were also carried out on a 2-storey full-scale H-shaped structure constructed by individual panels which were properly joined together. The performance and failure mode of all panels tested revealed strong coupling between flexure and shear due to the squat-type geometry of the panels. However due to their well-detailed reinforcement, all panels exhibited only a relatively gradual strength and stiffness degradation and in no case did any panel suffer from sudden shear failure. The prefabricated walls of the structural system investigated herein seem to meet all the requirements of Eurocode 8 for walls to be designed as “large lightly reinforced walls”; however this assumption should be supported with further experimental and analytical studies.     

Parametrical study of masonry walls subjected to in-plane loading through numerical modeling

This paper deals with the numerical assessment of the influence of parameters such as pre-compression level, aspect ratio, vertical and horizontal reinforcement ratios and boundary conditions on the lateral strength of masonry walls under in-plane loading. The numerical study is performed through the software DIANA^® based on the Finite Element Method. The validation of the numerical model is carried out from a database of available experimental results on masonry walls tested under cyclic lateral loading. Numerical results revealed that boundary conditions play a central role on the lateral behavior of masonry walls under in-plane loading and determine the influence of level of pre-compression as well as the reinforcement ratio on the wall strength. The lateral capacity of walls decreases with the increase of aspect ratio and with the decrease of pre-compression. Vertical steel bars appear to have almost no influence in the shear strength of masonry walls and horizontal reinforcement only increases the lateral strength of masonry walls if the shear response of the walls is determinant for failure, which is directly related to the boundary conditions.