寒冷地区无粘结预应力混凝土梁的抗弯与疲劳强度研究

针对我国行业标准《无粘结预应力混凝土结构技术规程》(以下简称《规程》)中,对无粘结预应力筋的极限应力设计取值规定的不足,根据大量的试验数据,推导出了适用于桥梁工程的无粘结预应力混凝土上部结构多种截面形式的无粘结筋极限应力增量实用简化计算方法。同时根据试验结果得出无粘结预应力混凝土受弯构件在反复荷载作用下的性能是可靠的结论。     

无粘结部分预应力混凝土框架抗震性能试验研究

本文通过两榀框架梁按不同预应力度配置无粘结预应力盘和非预应力筋的“强柱弱梁”型无粘结部分预应力混凝土框架在水平低周反复荷载作用下的试验研究，探讨其包括裂缝分布、破坏形态。极限承载力、无粘结筋应力变化、位移延性、耗能能力、恢复力特性等工作性能，并进一步分析了影响此类结构抗震性能的主要因素，为无粘结部分预应力混凝土框架在地震设防区域的应用提供参考。     

配置600MPa钢筋的无粘结部分预应力混凝土梁试验研究

通过进行9根配置600 MPa级钢筋的无粘结部分预应力混凝土梁的试验研究,研究预应力度、非预应力纵向受拉钢筋强度等级及配筋率、混凝土强度等级对无粘结部分预应力混凝土梁受弯承载力、应力增量及刚度的影响。研究结果表明:增加预应力度和非预应力筋配筋率能够显著提高配置600 MPa级钢筋的无粘结部分预应力混凝土梁的受弯承载力,减缓试验梁的刚度退化。随着预应力度或非预应力筋配筋率的增加,配置600 MPa级钢筋的无粘结部分预应力混凝土梁的预应力筋应力增量减小。提高非预应力钢筋强度等级,能够使预应力筋的极限应力增量和结构的极限承载能力得到提高。     

音乐学院25.7m跨后张法有粘结预应力框架梁设计

介绍了西安音乐学院演艺中心工程25.7m跨后张法有粘结预应力框架梁的设计方法,在8度抗震设防大跨结构中应采用预应力筋与非预应力筋的混合配筋方式,能较好地满足建筑空间和使用功能要求。但是由于我国现行规范中没有预应力混凝土结构的抗震设计专门条款及构造措施,而仅仅对预应力混凝土的抗震设计提出了一般的要求,在抗震区使用部分预应力混凝土结构保证构件截面延性很重要,同时应注意控制预应力度和截面的相对受压区高度。     

基于修正Park-Ang模型的PC框架结构损伤模型研究

为研究Park-Ang模型在预应力混凝土结构构件中的适用性,针对预应力混凝土构件,依据等效荷载法原理将构所受到的有效预压力作为轴向压力,并以此来计算预应力构件的轴压比;考虑有、无粘结预应力筋两种情况,基于预应力混凝土梁和普通钢筋混凝土梁的拟静力试验,利用1st Opt软件对Park-Ang模型参数β进行非线性拟合;最后,根据有、无粘结预应力混凝土框架结构的拟静力试验,利用本文修正的有、无粘结预应力混凝土构件的Park-Ang模型参数β计算其损伤,将计算结果与试验结果对比吻合良好,验证其适用性。     

无粘结部分预应力混凝土扁梁框架抗震性能试验研究

本文通过两榀按不同预应力度配置无粘结预应力筋、非预应力筋的“强柱弱梁”型无粘结部分预应力混凝土扁梁框架在水平低周反复荷载作用下的试验研究，探讨其包括裂缝分布、破坏形态、极限承载力、无粘结筋应力变化、位移延性、耗能能力等工作性能。     

高温后足尺有粘结预应力混凝土梁板力学性能研究

针对足尺有粘结预应力混凝土梁板高温后的抗弯承栽力开展了非线性计算分析。结果表明,综合配筋指标、有效预应力对高温后极限弯矩与常温下极限弯矩比值M_u~A/M_u的影响不大,预应力度和预应力筋的保护层厚度对M_u~A/M_u影响显著。高宽比近似相同的有粘结预应力混凝土梁,当第一排钢筋的保护层厚度相同时,受火时间为3 h,高度为700 mm的梁高温后截面承栽力下降幅度最大约为30%,高度为4500 mm的梁高温后截面承栽力下降幅度不到10%,高温后大尺度梁的力学性能优于小尺度梁。给出了考虑预应力筋保护层厚度和预应力度影响的有粘结预应力混凝土板M_u~A/M_u的计算公式,以及综合考虑预应力筋、非预应力筋合力点到梁底距离和预应力筋梁侧保护层厚度影响的有粘结预应力混凝土梁M_u~A/M_u的计算公式。     

底部开缝预应力剪力墙结构力学性能的有限元分析

根据现浇混凝土结构与装配混凝土结构的耗能特点,建立了底部开缝后张拉预应力摇摆剪力墙结构模型,并采用数值模拟方法研究其抗震耗能性能,分析分布钢筋、预应力水平、轴压力等参数对其力学性能的影响,并与同类型整体现浇剪力墙进行了对比分析。结果表明：底部开缝后张拉预应力摇摆剪力墙结构具有一定的耗能能力,虽然相对于现浇剪力墙结构,其承载力较低,但变形能力较强,墙体损伤和残余变形较小,并且具有较好的自复位能力。     

新型预制预应力混凝土框架结构有限元分析

为了研究新型预制预应力混凝土框架结构的抗震性能,本文采用ABAQUS软件对试验节点进行有限元分析,验证了建模方法的正确性,并以试验节点为原型,建立相应的两层两跨的新型预制预应力混凝土平面框架模型。采用低周往复加载方式分析了新型预制预应力混凝土框架结构和现浇框架结构的滞回性能,并模拟了新型预制预应力混凝土框架结构在不同的初始荷载、预应力筋数量及控制应力和U形筋配筋率下的滞回性能。结果表明,新型预制预应力混凝土框架和现浇框架的滞回性能非常接近;框架轴压比、预应力筋数量和U形筋配筋率对新型预制预应力混凝土框架的滞回性能有影响,而梁上荷载和预应力筋控制应力的影响较小。     

预应力混凝土结构非线性地震反应分析

本文针对预应力混凝土与普通混凝土不同的受力特点,提出了适合于分析预应力混凝土结构抗震性能的非线性有限元模型。模型首先将混凝土结构离散为杆单元,然后对各杆单元按分层组合原理分成许多混凝土层、预应力钢筋层和普通钢筋层,计算混凝土分层单元、预应力钢筋和普通钢筋的应力和应变,最后,根据钢筋与混凝土之间的粘结－滑移关系高速钢筋变形,根据混凝土弹性模量调整结构及杆单元变形,通过对普通混凝土构件和三个预应力混凝     

考虑楼板作用的钢筋混凝土框架有限元模型及并行计算效率

对于钢筋混凝土框架,考虑楼板与梁的协同作用可以更充分地体现结构静动力性能。本文首先采用分层壳单元模拟楼板,通过刚臂耦合梁板,建立了可以较好模拟梁板协同工作的框架结构有限元模型,并与其它3种采用简化假定的模型进行了比较。为了控制这种模型的分析误差,必须将梁、板划分为较小单元,所以需要耗费大量的计算机内存和时间。为此,比较分析了采用集群并行计算与普通串行计算的求解时间,结果说明对于中等到较大的框架模型,集群计算均可以大量减少计算时间。     

Performance of masonry enclosure walls: lessons learned from recent earthquakes

This paper discusses the issue of performance requirements and construction criteria for masonry enclosure and infill walls.Vertical building enclosures in European countries are very often constituted by non-load-bearing masonry walls, using horizontally perforated clay bricks.These walls are generally supported and confined by a reinforced concrete frame structure of columns and beams/slabs.Since these walls are commonly considered to be nonstructural elements and their influence on the structural response is ignored,their consideration in the design of structures as well as their connection to the adjacent structural elements is frequently negligent or insufficiently detailed.As a consequence,nonstructural elements,as for wall enclosures,are relatively sensitive to drift and acceleration demands when buildings are subjected to seismic actions. Many international standards and technical documents stress the need for design acceptability criteria for nonstructural elements,however they do not specifically indicate how to prevent collapse and severe cracking,and how to enhance the overall stability in the case of moderate to high seismic loading.Furthermore,a review of appropriate measures to improve enclosure wall performance and both in-plane and out-of-plane integrity under seismic actions is addressed.     

超长剪力墙隔震结构温度应力分析

温度作用是结构设计中不可忽视的作用,如何有效控制温度作用一直是一个重要的课题。近些年,随着建筑和结构的发展,出现越来越多的超长结构和隔震结构。对于超长结构的温度效应有许多学者做过相关的研究,但超长隔震结构的温度效应还研究甚少,温度作用下的结构变形和内力特点还不甚明晰。对超长剪力墙隔震结构的温度效应进行了探讨,利用有限元软件ETABS建立了结构的隔震模型和非隔震模型。通过对比2种模型在季节温差和混凝土收缩当量温差共同作用下的结构变形特点、构件内力和应力大小,分析隔震支座变形量与所在位置关系,发现超长隔震结构较超长非隔震结构,隔震层以上结构由于约束释放在温度作用下接近自由变形。而结构构件的内力和应力大大减小,得出隔震支座能充分消除结构因温度效应产生的不利影响,从而保护结构和构件的结论,对超长隔震结构的温度效应控制提供一定的思路和参考。     

Three‐dimensional beam‐truss model for reinforced concrete walls and slabs – part 1: modeling approach,validation, and parametric study for individual reinforced concrete walls

A three‐dimensional beam‐truss model for reinforced concrete (RC) walls developed by the first two authors in a previous study is modified to better represent the flexure–shear interaction and more accurately capture diagonal shear failures under static cyclic or dynamic loading. The modifications pertain to the element formulations and the determination of the inclination angle of the diagonal elements. The modified beam‐truss model is validated using the experimental test data of eight RC walls subjected to static cyclic loading, including two non‐planar RC walls under multiaxial cyclic loading. Five of the walls considered experienced diagonal shear failure after reaching their flexural strength, while the other three walls had a flexure‐dominated response. The numerically computed lateral force–lateral displacement and strain contours are compared with the experimentally recorded response and damage patterns for the walls. The effects of different model parameters on the computed results are examined by means of parametric analyses. Extension of the model to simulate RC slabs and coupled RC walls is presented in a companion paper. Copyright © 2016 John Wiley & Sons, Ltd.     

高温下栓钉剪力连接件的结构性能数值模拟研究

目前,钢混凝土组合梁由于其具有截面高度小、自重轻、延性好等优点而广泛应用于高层建筑和桥梁结构中。钢混凝土组合梁中,钢梁和混凝土板通过剪力连接件共同作用,钢混凝土组合梁的性能很大程度上依赖于剪力连接件的性能,因此剪力连接件是组合梁中的关键部位。栓钉是目前最常用的柔性剪力连接件。本文采用有限元软件ABAQUS,较系统地研究了高温下组合梁中栓钉破坏形态、破坏机理、抗剪承载力和荷载—滑移规律性能,为高温下组合梁抗火性能研究提供基础。模型中混凝土、栓钉和钢梁采用实体单元模拟,材料的力学特性和热工特性参数根据欧洲规范（EN 1994-1-2）。本文先用文献中的试验结果验证了数值模型的可靠性,并进一步研究了不同栓钉直径和不同混凝土强度等级时的高温下栓钉承栽力折减系数。研究表明,欧洲规范中高温下栓钉承栽力的计算公式是合理的,能较准确地预测栓钉在高温下的承栽力。     

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.     

Correlation studies on an RC frame shaking-table specimen

This paper presents the correlation of the results of a new model for the dynamic analysis of reinforced concrete (RC) frames with the experimental time history of a two storey RC frame shaking-table specimen. The frame member model consists of separate subelements that describe the deformations due to flexure, shear and bond slip in RC structural elements. The subelements are combined by superposition of flexibility matrices to form the frame element. A non-linear solution method which accounts for the unbalance of internal forces between different subelements during a given load increment is used with the model. The ability of the proposed model to describe the dynamic response of frame structures under earthquake excitations is evaluated by comparing the analytical results with experimental evidence from a two-storey, one bay reinforced concrete frame tested on the shaking-table. The model parameters for the shaking-table specimen are derived from available experimental evidence and first principles of reinforced concrete. The effect of reinforcing bar slip on the local and global dynamic response of the test structure is assessed. © 1997 John Wiley & Sons, Ltd.     

混凝土高层建筑结构地震破坏抗毁能力评估

提出基于构件性能的混凝土高层建筑结构地震破坏抗毁能力评估方法,采用强度与延性法分析混凝土高层建筑构件强度和变形,以对强震作用下混凝土高层建筑结构性能实施准确描述。基于建筑结构性能以及多条地震波情况下高层建筑结构倒塌极限状态的分析规范,采用IDA方法设置建筑结构抗倒塌能力系数,并依据该系数获取基于构件性能的混凝土高层建筑结构地震破坏抗毁能力评估流程,实现建筑结构地震破坏抗毁能力的准确评估。实验结果说明,所提方法实现了混凝土高层建筑结构地震破坏抗毁能力的准确评估。     

Effect of types of reinforcement on plastic hinge rotation parameters of RC beams under pushover and cyclic loading

Experimental evaluation of reinforced concrete beam specimens with different characteristics of reinforcement subjected to pushover and cyclic loading is presented.Plastic hinge rotation parameters are determined based on the idealization of pushover and hysteresis curves of reinforced concrete beam specimens constructed in two percentage of reinforcement(0.471%and 0.71%) with different ductile characteristics.The experimental test results provide a clear demarcation of the effect of types of loading and the types of reinforcement on the nonlinear performance characteristics of beam specimens.These results are helpful to update the nonlinear modeling parameters of beam components for the specific type of reinforcement used in the construction of a structure.The updated non-linear modeling parameters of beam components in lumped plasticity model are compared with the values of ASCE/SEI 41-06(2007) used for the performance based design of structures.     

有缝重力坝动力非线性数值计算模型及其应用

对于有缝重力坝的分析，基于连续介质力学的界面单元-有限元方法难于比较精确地模拟缝间的接触应力，从而无法合理地估算坝体应力与变形。作者对于多体系统和分区连续介质所发展的非连续变形计算力学模型能够根据接触界面的本构特性及其力学和运动学约束条件精确地再现受力过程中界面相互作用力的传递与非连续变形状态，本文将其应用于有缝重力坝的动力分析。实例数值分析表明该模型的计算结果从定性上讲是合理的，并且为判断坝体缝隙的工作状态与界面应力提供了有力的依据。