预应力装配混凝土梁非线性有限元分析

利用ADINA有限元软件对4个无粘结预应力装配混凝土节点进行了非线性有限元分析,并且对分析结果与试验结果进行了对比。结果显示:所采用的分析模型在梁柱缝隙处的开合、应力分布、试件变形和恢复力骨架关系上与试验吻合较好,说明所采用的分析单元和模型有利于详细了解无粘结预应力装配梁的非线性性能和抗震性能。     

混合装配无粘结预应力梁加固试验研究

本文采用碳纤维布和外包钢两种加固方法,对6个混合装配无粘结预应力梁进行了低周反复加载试验。考虑了初始预应力度、后穿非预应力筋的强度、面积和不同加固方法等参数变化。试验表明:采用无粘结预应力混合装配的梁,在耗能和承载能力等方面比全预应力装配构件有所提高,加固后构件自恢复能力仍然较强(残余变形小),在较大非线性位移下试件破坏较少。文中分析了加固与未加固试件的恢复力特性、延性、耗能等抗震性能与试验参数的关系,为其今后在地震地区的施工和设计提出一个经济、合理的建议。     

Experimental investigation of dry mechanical beam–column joints for precast concrete based frames

This paper proposes dry mechanical beam–column joints for fully restrained moment connections of concrete components. This novel joint can be used for reinforced concrete precast frames and steel–concrete composite precast frames. The new dry mechanical joint consists of extended steel plates with bolts designed to transfer tension and compression forces, providing fully restrained moment connections at the beam–column joint. The extended end plate with bolts introduced for column‐beam joint assembly was originally used in the steel moment frame, as introduced in AISC 358. This study developed similar but unique mechanical joint details for concrete frames in order to provide fully restrained moment connections for both steel–concrete composite precast frames and reinforced concrete precast frames. Experimental and analytical investigations were performed to verify the structural behavior of fully restrained moment connections for concrete components in order to identify the parameters that influence the structural behavior of dry mechanical moment concrete connections. These connections are expected to be used in modular offsite construction for buildings and heavy industrial plants. Copyright © 2016 John Wiley & Sons, Ltd.     

Behaviors of semi‐precast beam made of recycled aggregate concrete

This paper presents behaviors of semi‐precast beams made of recycled aggregate concrete (RAC) including flexural and shear performance. Specially, cracking patterns, deflections and bearing capacities of U‐typed and C‐typed beams are intensively examined, analyzed and discussed. In the study of flexural behavior, a main parameter is reinforcement ratio, whereas the shear span‐to‐depth ratio and types of precast section are parameters in the investigation of shear behavior. First, the flexural tests show that the bearing capacity and stiffness of RAC beams are increased with the increase of reinforcement ratio, whereas the ductility is decreased with the reinforcement ratio; the plane section assumption that applies to semi‐precast beam with RAC is possible. Second, the shear tests show that the shear capacity of RAC semi‐precast beam increases with the decrease of the shear span‐to‐depth ratio. The types of semi‐precast section have no significant influence on performances of semi‐precast beam. However, the testing phenomenon of the interface between the precast and cast‐in situ parts is presented in this study and needs further study. Finally, both flexural and shear test results reveal that the formulas in the current Chinese technical code for RAC are feasible for design. Copyright © 2013 John Wiley & Sons, Ltd.     

型钢再生混凝土柱-钢梁组合框架节点受力性能非线性分析

在型钢再生混凝土柱-钢梁组合框架节点拟静力试验基础上,采用ABAQUS有限元软件建立了组合框架节点的数值计算模型,对该组合框架节点在水平荷载作用下的受力非线性行为进行了有限元分析,获取了组合框架节点的破坏过程、破坏形态、应力云图、荷载-位移曲线及荷载特征值,并对节点的承载力计算值与试验值进行了比较,验证了有限元计算模型的合理性,进而分析了有限元拓展参数对组合框架节点受力性能的影响规律。结果表明:有限元计算结果与试验结果吻合较好,该有限元模型能较好地模拟该组合框架节点在水平荷载作用下的受力性能;另外,提高再生混凝土强度或者箍筋强度对组合框架节点的抗剪承载力是有利的,但节点的延性变形能力有所降低;组合框架节点的抗剪承载力随着型钢强度的提高而显著增加,但节点的变形能力变化不大;增加体积配箍率或型钢配钢率可以明显提高组合框架节点的抗剪承载力和变形能力。     

装配式容差剪力墙及其推复性能分析

装配式建筑是我国建筑行业发展的一个重要方向,近年来得到了很大的发展.快速的建造方式对构件的安装误差控制要求较高,尤其是钢筋,钢板等预埋件的精度提出更高的要求;另一方面,装配式构件之间连接易导致结构发生节点失效的脆性破坏模式.为此,文章提出了一种具有较大容差能力的装配式剪力墙结构,使用型钢对上下剪力墙进行连接,同时连接用...     

柱双边型钢暗牛腿下混凝土的局压计算初探

型钢暗牛腿是预制混凝土框架常采用的一种竖向承载构件。在预制混凝土框架型钢暗牛腿节点中,型钢下混凝土的局压验算至关重要。结合中柱节点构造型钢暗牛腿的受力特点,提出考虑初始压应力与水平力的混凝土局压承载力计算公式,讨论并得出了影响混凝土局部抗压承载力的因素。提出的混凝土局压验算方法考虑了柱内混凝土的初始应力和型钢传来的水平力等因素的影响,可为此类双边型钢暗牛腿节点的局压计算提供参考。     

Seismic response of self‐centering precast concrete frames with hysteretic dampers

With the rapid development of cities and the invasion of major natural disasters such as earthquakes, the resilience city as a new design concept has been paid more and more attention. As an important branch of self‐centering seismic resisting system, self‐centering concrete frame system has been studied by many scholars. These studies prove that self‐centering concrete frame structure has excellent self‐centering ability but poor energy dissipation capacity. Adhering to the working principle of self‐centering structure and considering the development concepts of building industrialization and modularization, this paper proposed a kind of self‐centering precast concrete frame with hysteretic damper (SCPCHD). In order to verify its energy dissipation capacity and seismic performance, elaborate finite element models were established and elastoplastic dynamic time history analyses were carried out. The results showed that the SCPCHD frame has a similar interstory displacement response to the reinforced concrete (RC) frame and the energy dissipation performance of its joint is obviously superior to the RC frame under rare earthquake because the SCPCHD frame has low damage characteristics and excellent damping device. In summary, this paper proves the feasibility and superiority of the SCPCHD frame, providing reliable support for further research.     

混凝土异形柱-钢梁装配式节点受剪性能试验研究

为研究混凝土异形柱-钢梁装配式框架节点核心区的受剪性能,按照预制混凝土异形柱中预埋钢牛腿节点未加强、增配X形筋、增配X形钢板三种方式,分别制作3个预制混凝土异形柱-钢梁节点试件进行拟静力试验,得到其破坏特征、承载力、滞回曲线、刚度退化、耗能能力等抗震性能指标。由节点剪切变形、节点区钢筋应变、钢板应变测量结果,分析了不同牛腿加设方式对节点核心区受力性能的影响。结果表明：试件位移延性系数在3.22~5.94之间,破坏时位移角都超过1/50,抗震性能良好;牛腿内侧加设的X形钢筋与X形钢板均与节点核心区混凝土协同受力,可有效提高节点核心区受剪承载力。采用有限元软件ABAQUS对采用X形钢板增强的试件进行了数值模拟和参数分析,依据试验分析结果,推导出X形钢板增强的预制异形柱-钢梁混合装配式框架节点核心区受剪承载力计算公式,计算结果与试验实测值和有限元模拟值吻合较好。     

Losses of prestressed forces of pre‐tensioned precast composite beams

Herein, the authors propose prestressed composite beams with steel sections at both ends of the precast beams in order to provide flexural strength against negative moments at both ends. This study extends the use of prestressed precast composite beams by understanding the instantaneous and time‐dependent losses of prestressed forces. This study also attempts to find out whether the currently available equations predicting instantaneous and time‐dependent losses of prestress can be used to predict the performance of prestressed precast composite beams. In this study, analytically calculated prestress losses of precast composite beams were compared with the loss of prestress observed during experiment to evaluate the eligibility of the proposed analytical approach and to calculate the losses of prestressing forces for precast composite beams. The influence of steel sections installed at both ends of the precast beams on the loss of prestress was also investigated to estimate prestress loss of the prestressed precast composite beams. The 20% loss was recommended for the instantaneous prestress loss for the precast composite beams, accounting for the contribution of T steel members of precast beams to the elastic contraction.     

Seismic collapse analysis of high‐rise reinforced concrete frames under long‐period ground motions

Structural damages associated with buckling of longitudinal reinforcing steel and crushing of concrete induce strength and stiffness degradation in reinforced concrete (RC) beams and columns. This paper presents a numerical investigation on earthquake‐induced damages and collapse of typical high‐rise RC buildings model incorporating strength degradation (SD) effects. In a simple finite‐element analysis program with the generalized stress fiber discretization, hysteretic constitutive models primarily dominate the inelastic behavior. Buckling of reinforcing steel and crushing of confined concrete are taken into accounted to the stress–strain relationship of fiber elements. The SD effect in components with small hoop ratio tends to amplify the seismic responses high‐rise RC moment‐resisting frames when the intensity of ground motions exceeds the design level. Buckling of steel rebar and crushing of concrete should be fully considered together with the P‐Δ effect for collapse simulations.     

预制装配式框架干式企口连接中缺口梁的受力性能分析

在全预制钢筋混凝土框架梁柱干式企口连接中,钢筋混凝土缺口梁是重要的传力构件。应用拉压杆模型和剪力摩擦等理论对刚性企口连接中缺口梁的各种破坏形式进行分析,推导出相应的承载力公式,然后应用有限元分析软件ANSYS对该连接中钢筋混凝土缺口梁进行有限元分析,并对承载力公式进行了验证。     

装配式内置双钢套管混凝土组合#br# 剪力墙的抗震性能试验研究

提出一种可适用于高层建筑的装配式内置双钢套管混凝土组合剪力墙,通过6个剪跨比为2.86的两层组合剪力墙试件的拟静力抗震试验,考察试件的装配整体性,研究组合墙体的破坏机理和抗震性能。结果表明：试件的破坏形态整体为弯剪复合破坏,特征表现为约束边缘构件的竖向钢筋和外钢管受拉屈服、混凝土压溃、外钢管有压鼓曲,剪切斜裂缝明显;连接坐浆层和预制墙体均有裂缝发展和分布,两者之间无相对错动;试件滞回曲线有捏拢现象,峰值荷载后骨架曲线有平缓承载力下降段,塑性变形和延性能力良好,表现出良好的装配整体性;螺栓径向固结内、外钢管可实现钢套管间的约束和连接;平面外荷载偏心对滞回性能有重要影响,较大偏压矩试件仍有较好的变形和延性能力,内置钢管混凝土芯柱发挥了可靠连接作用,可提高装配墙体的面外压弯能力;钢管混凝土截面含量比小的试件有较大的位移延性,预制组合墙的参数组合还需优化。     

Seismic behavior of tall buildings using steel–concrete composite columns and shear walls

For the seismic design of tall building structures, the behavior under severe earthquakes should be carefully considered and the upper limit of inter‐story deformations are often defined by the design codes. To improve the performance of structures under severe earthquakes, composite structural members, including steel reinforced column and steel plate reinforced shear wall, are often adopted. In the present work, the seismic behavior of tall buildings using steel–concrete composite columns and shear walls is investigated numerically. Fiber beam–column element models and multilayer shell models are adopted to establish the finite element model of structure, and the material nonlinearities are described by the plasticity and damage models. The accuracy of the developed models is verified by the experimental results of a single shear wall. Systematic numerical simulations are performed for the tall building structures subjected to different earthquakes. The comparative study indicates that the nonlinear redistribution of internal forces plays a very important role for the performance of tall buildings under severe earthquakes.     

钢-混凝土叠合板组合梁在苇沟桥改造加固中的应用

钢 -混凝土组合梁以其承载力高、刚度大等优点 ,在我国城市的立体交通建设中应用前景广阔。结合实际工程 ,介绍了钢 -混凝土叠合板组合梁在桥梁改造加固中的应用。实践证明 ,钢 -混凝土叠合板组合梁可以大幅度提高结构承载力 ,降低结构自重 ,减小挠度等 ,另外还可以节省支模 ,缩短施工周期。     

新型装配式不对称混合连接节点试验研究

不对称混合连接是预制装配式混凝土结构的一种新型连接方式.预制梁和柱通过无黏结后张预应力筋装配形成整体,作为耗能元件的普通钢筋仅设置在梁截面上部,并在梁柱连接处作部分无黏结处理.介绍三榀不对称混合连接边节点的低周反复加载试验,试验结果显示:试件的破坏都集中在梁柱接触面,梁柱构件本身及节点核心区破坏轻微;试件的滞回曲线均呈现"S"形,曲线明显呈不对称形状,正向加载时曲线更为饱满;试件的位移延性系数在3.75～5.0,最终等效黏滞阻尼系数为8%～10%.     

预制预应力装配式框架节点抗震性能有限元分析

预制装配式框架梁柱节点通过后张预应力和非预应力插入钢筋混合式连接是由美国PCI学会提出的一种新型抗震节点形式。对该类节点的抗震性能进行了非线性有限元分析,对比研究了该预制装配式节点与现浇节点的承载能力、滞回性能及耗能能力等,可供相关研究参考。     

Seismic performance of precast hollow bridge piers with different construction details

Currently the design scheme of precast hollow concrete bridge piers will be adopted in bridge design in China, but there is no code including specific design details of precast segmental piers in high seismic risk area. For comparative study of seismic performance of the hollow bridge piers which had different design details, six specimens of hollow section bridge pier were designed and tested. The specimens consist of the monolithic cast-in-place concrete bridge pier, precast segmental prestressed pier with cast-in-place joint and precast segmental concrete bridge pier with dry joints. Results show that all specimens have good displacement capacity. The bridge pier with bonded prestressed strands exhibits better energy dissipation capacity and higher strength. The un-bonded prestressed strand bridge pier displays less residual plastic displacement and energy dissipation capacity. The bridge pier with both bonded prestressed strands at the edge of the section and un-bonded in the center of the section not only exhibits more ductility capacity and less residual plastic displacement, but also shows better energy dissipation capacity. Compared with experimental results of prestressed bridge columns, analytical result demonstrates the developed numerical analysis model would provide the reasonable and accurate results.     

The effects of axial tension on the sagging-moment regions of composite beams

This paper studies the effects of axial tension on the sagging moment regions of steel–concrete composite beams. The study comprised an extensive experimental programme and nonlinear finite element analyses. Six composite beams were designed and tested under the combined effects of axial tension and positive bending moment. The beams were loaded to their ultimate capacity and the experimental moment-axial tension interaction diagram was constructed. Following the tests, a finite element model was used to simulate the nonlinear response of the composite beams. The validity of the model was thoroughly assessed against the available experimental data and a parametric study was conducted to study different beam sizes and the effect of partial shear connection on the interaction diagram. It was found that the moment capacity of a composite beam is reduced under the presence of an axial tensile force acting in the steel beam section. In addition, the use of partial shear connection does not affect significantly the shape of the interaction diagram. The tensile capacity of the composite section, however, is limited by the axial capacity of the steel beam alone. Based on the experimental results and the finite element analyses, a simplified equation is proposed for the design of composite beams subjected to positive bending and axial tension.