混凝土收缩徐变参数影响分析

影响混凝土收缩徐变的因素很多,主要有环境湿度、混凝土强度、混凝土理论厚度、初始加载龄期等。本文以一钢筋混凝土柱为算例,采用ANSYS进行参数分析,研究以上主要因素对混凝土收缩徐变的影响。并采用正交试验设计方法,分析混凝土收缩徐变受各因素影响的敏感性。结果表明,环境湿度是影响混凝土收缩徐变的最主要因素,其次是加载龄期,然后是混凝土强度,最后是理论厚度。     

浅析单桩在竖向载荷作用下的工作性状

简单分析了单根桩在上部荷载作用下随着荷载的变化端承力与桩侧摩擦力的变化规律，指出了影响桩-土体系荷载传递的主要因素，为该类结构的设计与施工提供了理论基础。     

首层架空层转换结构的侧向刚度控制参数探讨

通过一系列在首层架空层设置转换层的高层建筑的有限元分析,对楼层侧向刚度比、等效剪切刚度比和等效侧向刚度比三种转换层结构侧向刚度控制参数进行了探讨。讨论了在不同首层层高条件下,转换层下部结构侧向刚度改变对这三种侧向刚度比控制参数的影响。结果表明,首层层高较高且与相邻层层高相差悬殊时,楼层侧向刚度比和等效剪切刚度比容易大幅度超过现行规范限值,但并不能由此判断转换层下部结构侧向刚度严重不足。这种情况下,等效侧向刚度比较好地体现了转换层上下结构的侧向刚度关系,宜按等效侧向刚度比对结构侧向刚度进行控制,但其上限取值有待进一步研究。     

高强混凝土的收缩和早期徐变特性

以掺硅粉的大流动性高强混凝土为研究对象,对混凝土在常温常湿的室内条件下的自收缩、干缩收缩和徐变特性进行了实验测定,讨论了干燥开始龄期和加载龄期对收缩和徐变的影响,并通过引入凝结时间的要素对MC90的收缩和徐变系数预测式进行了修正,使其也能适合于早龄期。     

庆化开元高科大厦转换结构设计

庆化开元高科大厦是B级高度的复杂高层建筑结构 ,其建筑竖向上的结构转换层与建筑使用功能转换层不在同一层 ,且结构转换层上下两部分的轴网呈 45°相交 ,这给结构设计带来了较大的难度。重点介绍了转换层的选型、整体计算模型的处理 ,并提供了控制转换层上下层等效剪切刚度比、层间侧向刚度比的有效方法 ,很好地处理了建筑转换层、设备转换层、结构转换层之间的关系。     

某高层建筑侧向刚度比对转换层结构抗震性能的影响

梁式转换层结构作为目前高层建筑常用的垂直转换形式,抗震设计至关重要。结合一工程实例,通过应用分析软件SAP2000,研究了侧向刚度比对结构抗震性能的影响,其中包括不同侧向刚度比对转换层的地震力,倾覆弯矩,结构周期的影响。     

核筒悬挂建筑结构体系的减震性能研究

通过建立核筒悬挂建筑结构体系的分析模型,分析了其动力响应的影响参数及设置,并推导了运动方程.分析表明,核筒悬挂减震结构具有显著减小水平地震作用的效果,是一种有着很好发展前景的结构体系.该研究工作为这种新型结构体系的工程应用提供了理论基础.     

高大模板结构尺寸的换算及支撑架布置浅谈

通过各规范中荷载计算公式得出高大模板梁板尺寸的界定,使用PKPM软件计算各立杆间距所能承受的高大模板构件尺寸,并介绍支撑架体布设思路。     

Creep and shrinkage behaviour of CFRP-reinforced mortar

This paper deals with the reinforcement of mortar with external composite materials. The mortar specimens were strengthened with CFRP (Carbon Fibres Reinforced Polymer) plates on two or four faces. Creep tests were run for 7 or 28 days with applied stress level at 30% of ultimate stress. Experimental results show a clear improvement of short-term creep behaviour for the reinforced mortar. There is no evidence of shrinkage reduction due to the reinforcement. Drying is modelled using a non linear diffusion equation and shrinkage is numerically calculated. In both cases, accurate predictions of experimental results were obtained.     

Full-scale long-term experiments of simply supported composite beams with solid slabs

This paper presents an experimental study aimed at the evaluation of the long-term behaviour of composite steel-concrete beams designed with partial shear connection formed by a steel joist and a solid concrete slab. Three full-scale simply supported beams with identical spans and cross-sections were prepared and tested. These specimens were designed as secondary beams of a typical composite flooring system based on Australian guidelines with the lowest permitted level of degree of shear connection of 0.5. They were cast simultaneously to enable comparisons with respect to pouring and loading conditions. One beam was cast un-propped and was kept unloaded for the whole duration of the long-term tests to measure shrinkage effects. The remaining two beams, cast under un-propped and propped conditions, respectively, were subjected to a sustained uniformly distributed load. Standard short-term and long-term tests were carried out to obtain the relevant material properties of both the steel and the concrete. Short-term and long-term push-out tests were carried out to obtain information on the response of the shear connectors. The experimental results were modelled by means of the finite element method. The time-dependent behaviour was depicted using a step-by-step procedure, while the steel joist and reinforcement were assumed to remain linear elastic. Two constitutive relationships were adopted for the shear connection, i.e., a linear-elastic one, and a new time-dependent one, to account for the long-term effects produced in the complex stress state of the concrete surrounding the shear connectors. The latter representation is intended to fall within the framework of simplified approaches suitable for design applications. Considerations of the accuracy of the numerical predictions are presented based on the two shear connection models.     

高层建筑厚板转换层结构设计

扼要介绍了位于低烈度区的三箭·银苑花园高层建筑结构采用高位厚板转换层的设计要点及构造情况 ,并介绍了转换厚板施工阶段的温度裂缝控制验算 ,以及所采取的控制温度裂缝的措施。     

超高层建筑如何与城市共生

城市结构,文化及景观的思考让建筑的营造富含了戏剧色彩,可以说建筑本身即体现了城市的内涵与外在的表象,它可以让城市产生独特的魅力,也可以让城市感觉急促,喘不过气。在设计的过程中,可以通过一些合理有效的方法来缓解这种看似矛盾的关系     

带斜柱转换的框支剪力墙结构工程应用对比分析

本文介绍了斜柱转换在工程中的应用,并对一个一般高层(建筑高度58.05 m)分别采用斜柱转换和实腹梁转换的计算结果进行对比分析,同时对比斜柱转换结构在100 m高层中应用的整体性能。结果表明:斜柱转换能明显改善转换层与其相邻上层结构的侧向刚度比,降低转换梁的截面尺寸,节省建筑的使用空间;斜柱转换在一般高层中的应用对控制转换层与其相邻上层的剪切刚度比效果更好,在100 m高层中的应用对控制结构整体水平位移效果更好。     

带斜柱转换的框支剪力墙结构整体性能分析

本文从转换层与其相邻上层结构的侧向刚度比、结构的嵌固部位以及0.2V0系数调整这三个方面,总结了框支剪力墙结构设计时应注意的问题。介绍了斜柱转换在工程中的应用,并对一实际工程分别采用斜柱转换和实腹梁转换的计算结果进行对比分析。结果表明:斜柱转换能明显改善转换层与其相邻上层结构的侧向刚度比,降低转换梁的截面尺寸,节省建筑的使用空间。     

Time analysis of composite beams with partial interaction using available modelling techniques: A comparative study

This paper presents a comparison of available numerical structural formulations for the short- and long-term analysis of composite beams with partial shear interaction. The finite difference method, the finite element method, the direct stiffness method and the exact analytical model have been considered, and both the instantaneous analysis and the time analysis based on the age-adjusted effective modulus method (AEMM) have been carried out. For modelling based on the first two of these formulations, a spatial discretisation and a discretisation in the time domain are required, while only the time discretisation needs to be specified for the direct stiffness method. The results obtained using these formulations are compared qualitatively and their accuracy is estimated, adopting the exact analytical model as a benchmark reference with the objective of establishing the minimum spatial discretisations required to keep the error within an acceptable tolerance. These comparisons are carried out for simply supported beams, propped cantilevers and fixed ended beams, from which the qualitative behaviour of these formulations in the modelling of continuous beams can also be deduced.     

带梁式转换层的联肢剪力墙结构的侧移刚度比计算

梁式换层结构上、下侧移刚度比是此类结构设计中的重要控制指标,现行规范中的计算方法所得到的结果与有限元法得到的结果有较大的出入。针对这一问题,考虑了上部剪力墙与下部框架的共同作用,分别采用带刚域的框架模型和连续连接介质模型模拟框架和剪力墙,导出了带梁式转换层的框支联肢墙结构在侧向集中荷载作用下的侧移计算公式,在此基础上得到了框支联肢墙结构上下侧移刚度比计算公式。数值计算表明,该方法算得的侧移刚度比与有限元方法的计算结果比较接近。     

四川彭州人民医院病房综合楼基础隔震结构设计

结合四川彭州人民医院病房综合楼项目,对基础隔震结构设计的流程及高层框架剪力墙结构隔震设计的特点、考虑拉压刚度不同的计算方法做简要介绍。该工程为隔震技术在类似建筑中的应用提供了一个实例。