大跨单层折面空间网格结构施工全过程分析

以深圳大运会体育场大跨屋盖为工程背景,分析了新型＂单层折面空间网格结构＂的受力特点;基于大跨空间网格结构的矩阵力学模型,考虑结构在施工过程中几何时变、约束时变、荷载时变等特征的基础上,建立了考虑时变效应的施工状态非线性求解分析方法及其步骤,并利用ANSYS的APDL语言编制了单层折面空间网格结构的施工全过程分析程序。分析结果表明：结构在施工过程中的最大位移、最大应力均随之出现一定程度的波动;支撑内力在卸载过程中均有较大波动,其波动幅度最大接近于初始值的2倍;施工完成时结构中的应力与设计状态存在差异,位移分布也出现了不对称的现象。分析结果可为临时支撑的设计与施工过程的控制提供指导和依据。     

多层滑移隔震建筑结构的简化模型及其分析精度

多层滑移隔震结构可通过广义双自由度模型(单自由度或双自由度模型)进行简化计算分析。本文首先由振型分解 理论,探讨了滑移隔震结构双自由度简化模型分析参数质量比的取值,在此基础上,通过数值试验的方法,研究了在不同 地震波类型、地震波幅值、结构层数、上部结构固有周期、滑移摩擦系数和模型分析参数质量比影响因素下,广义双自由度 模型对多层滑移隔震结构最大滑移位移的计算精度和适应性。研究表明,上述各因素对模型的分析精度都有影响,其中上 部结构基本周期和模型分析参数质量比为两个较敏感因素。本文由此建议了一个优化分析参数双自由度模型,该模型可 分析上部结构固有周期小于1s结构的最大位移反应,其误差可控制在14％以内。     

减震结构粘滞阻尼器参数优化分析

研究了基于响应面法进行减震结构非线性粘滞阻尼器参数优化设计的方法,该方法包括试验设计、有限元分析、响应面函数拟合和参数优化.以一榀钢筋混凝土框架结构非线性粘滞阻尼器参数优化为例,以所有粘滞阻尼器提供的阻尼力之和最小为优化目标函数,层间最大位移限值作为约束条件,建立粘滞阻尼器参数优化的数学模型,然后运用非线性规划优化方法进行参数优化.算例研究结果表明:基于响应面法进行粘滞阻尼器参数优化,既能保证结构层间位移小于限值,又能降低建造成本.     

内凹式索拱结构极限承载力研究

采用考虑双重非线性的有限元方法对内凹式索拱结构的极限承载力进行了参数研究。主要分析了5种荷载形式下支座形式、拱矢跨比、索矢跨比、撑杆数量、拱截面、索截面、初始张拉力和初始缺陷等参数对内凹式索拱结构承载力的影响;并与仅考虑几何非线性的结果进行了对比。分析结果表明:支座形式、矢跨比、撑杆数量、拱截面等因素对结构承载力影响较大;索截面、初始张拉力和初始缺陷等对结构承载力影响较小;其合理的取值范围为:拱矢跨比取0.125~0.20,索矢跨比取0.05~0.10,索截面积取拱截面积的4%~6%,与拱结构相比,该结构的整体稳定性、极限承载力、整体刚度都大幅度提高,对缺陷的敏感度减低;半跨荷载是结构设计的控制荷载,给出了快速确定初始张拉力的简化计算公式。     

地铁高架车站型钢混凝土组合框架设计方法研究

为提出型钢混凝土构件的承载力计算的计算方法,选取实际工程案例中的一榀型钢混凝土组合框架,按照《建规》(GBJ 68-84)中的极限状态概率设计法进行设计并利用本文提出的容许应力法进行验算,确定最终截面设计。在ABAQUS有限元软件中建立型钢混凝土组合框架三维有限元实体模型,并施加对应设计荷载,进行有限元分析。根据计算结果可知本文提出的容许应力法的截面设计流程具有较好的合理性,可以有效计算型钢混凝土框架中混凝土、钢筋和型钢应力。     

全装配式钢筋混凝土框架-剪力墙结构抗震性能试验研究

为研究采用预制剪力墙、预制框架的全装配式RC框架-剪力墙结构的抗震性能,对2榀1/2比例两层两跨RC框架-剪力墙结构子结构模型试件（其中1榀为全装配试件PCFW2,1榀为全现浇对比试件RCFW）进行了低周反复荷载试验,分析了结构的破坏机制、破坏形态、塑性铰开展、滞回性能、位移延性、刚度退化和耗能能力等。结果表明：全装配式试件PCFW2与全现浇对比试件RCFW的开裂荷载相当,破坏过程和最终破坏形态基本相同;灌浆套筒、约束浆锚可有效传递钢筋应力;全装配式试件PCFW2整体性良好,其屈服荷载、峰值荷载、极限荷载均略大于全现浇对比试件RCFW的相应值,但相差不超过13.0%,位移延性系数较全现浇试件RCFW的略低。在大部分受力阶段,试件PCFW2耗能优于试件RCFW。建议全装配式框架-剪力墙结构中剪力墙的边柱（或边缘）纵筋,采用灌浆套筒连接,其余部分采用约束浆锚搭接连接,而框架湿节点处的后浇混凝土采用微膨胀混凝土。     

雪荷载下加油站罩棚倒塌事故分析及若干建议

介绍了苏南地区多个加油站罩棚在雪荷载下发生坍塌事故的情况,选取了3个具有代表性且不同结构形式的加油站罩棚作为例子,分别分析了事故发生的原因,指出了结构设计、工程施工中普遍存在的问题.对今后类似工程的建设提出了设计、施工和使用上的建议.     

Numerical simulation of the shear behaviour of reinforced concrete rectangular beam specimens with or without FRP-strip shear reinforcement

The successful validation of a numerical model is presented that can realistically approximate the shear behaviour of reinforced concrete (R/C) rectangular beams strengthened against shear with externally applied open hoop fibre reinforcing polymer (FRP) strips. For this purpose, the measured load-deformation response of ten (10) full-scale R/C beam specimens is utilised. These specimens were loaded monotonically in a four-point bending arrangement up to failure. Open hoop FRP strip shear reinforcement was applied externally to upgrade the shear capacity of eight (8) R/C beam specimens. Four of these specimens had these FRP strips without anchorage, whereas for the other four the FRP strips were attached together with novel anchoring devices. This successful numerical simulation predicts with a very good degree of approximation the observed load-deformation behaviour and the ultimate shear capacity of all these specimens as well as the observed modes of failure including diagonal concrete cracking, debonding of the FRP strips in the case of no anchoring, or the plastification of parts of the anchoring devices plus the adjacent crushing of the concrete.     

Effect of joint stiffness on the stability of cable-braced grid shells

Bolted joints used in cable-braced grid shells are typically semi-rigid joints, and the joint stiffness has a significant effect on the stability of cable-braced grid shells. The effect of joint stiffness on the stability of cable-braced grid shells is studied in this paper. Based on the experimental results of improved bolted joints, finite element models of elliptic paraboloid cable-braced grid shells with bolted joints are established, and spring elements are used to simulate the joint stiffness. The effect of the joint stiffness on the nonlinear buckling load is studied by changing the joint stiffness. The main conclusions are as follows. First, the joint rotational stiffness has a significant effect on the failure mode. When the joint rotational stiffness is small to a certain extent, the failure mode of cable-braced grid shells changes from overall buckling to local buckling. Second, the nonlinear failure mode is similar to the first-order eigenvalue buckling mode and the maximal compression stress distribution. The structural integrity is weakened, and the maximal steel tube compression stress decreases with the decrease of the joint rotational stiffness. The smaller the joint rotational stiffness, the lower the utilization rate of steel strength. The results suggest that the joint stiffness of elliptic paraboloid cable-braced grid shells should not be less than 20% of the rigid joint stiffness.