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...     

钢筋混凝土剪力墙耐火性能及抗火设计

钢筋混凝土剪力墙是高层建筑结构中的重要构件,深入研究其耐火性能并进行合理科学的抗火设计至关重要。为此,简要回顾了钢筋混凝土剪力墙火灾下力学性能的研究现状,介绍了Eurocode 2、BS 8110-2、ACI 216R-89、AS 3600-2001、NS 3473E-1992、NZS 3101、GB 50045—95和GB 50016—2006规范的有关设计要求,探讨了钢筋混凝土剪力墙耐火性能及抗火设计的若干问题。     

CFRP筋钢筋混凝土剪力墙自复位性能试验研究

通过对1片钢筋混凝土剪力墙和4片配有碳纤维增强聚合物(CFRP)筋的剪力墙的低周反复荷载试验,在分析试验中测得的裂缝宽度、裂缝的发展和分布形态、侧向变形的基础上,研究了在钢筋混凝土剪力墙的适当位置部分或全部配置CFRP筋对剪力墙的残余裂缝和残余变形等自复位性能的影响规律。研究结果表明:与普通钢筋混凝土剪力墙相比,配有CFRP筋的剪力墙的开裂荷载较低,裂缝较多,裂缝分布分布范围较广,墙体的最大裂缝宽度、残余裂缝宽度和侧向残余变形分别降低了60%、70%和90%,说明在剪力墙中合理配置CFRP筋能使剪力墙具有优异的自复位性能。     

低剪跨比双钢板-混凝土组合剪力墙抗震性能试验研究

为研究低剪跨比双钢板-混凝土组合剪力墙的抗震性能,完成了2片低剪跨比双钢板-混凝土组合剪力墙和1片低剪跨比钢筋混凝土剪力墙试验,研究了高轴压比剪力墙在低周往复荷载作用下的变形能力、破坏模式,得到了试件滞回曲线、骨架曲线、承载力、位移延性系数、刚度退化、承载力退化和耗能能力等,分析了不同形式连接件对抗震性能的影响。试验结果表明：与钢筋混凝土剪力墙相比,低剪跨比双钢板-混凝土组合剪力墙受剪承载力显著提高,具有良好的延性和耗能能力,抗震性能良好。     

火灾下钢筋混凝土剪力墙温度场数值模拟

为了研究配筋率、升温曲线、多面受火、传热系数等因素对钢筋混凝土剪力墙温度场的影响,利用COMSOL多物理场建模与仿真软件对火灾下钢筋混凝土剪力墙温度场进行模拟,并得到不同因素变化条件下的剪力墙的温度场分布规律,模拟结果与试验结果符合良好.对温度场模拟中各参数对温度场的影响进行了讨论,结果表明:受火时间越长,钢筋混凝土剪...     

Fire response of exterior reinforced concrete beam-column subassemblages

Investigating the structural response of reinforced concrete beam-column sub-assemblies at elevated temperatures is the purpose of this paper. This goal was achieved by conducting the ISO-834 standard fire test on two identical one-third scaled reinforced concrete beam-column subassemblage test specimens. The test specimens, which each consisted of one reinforced concrete cantilever beam anchored at the mid-height of a reinforced concrete column, were installed together in a full scale furnace and subjected to downward and upward service loads, respectively. The fire compartment fully engulfed the cantilever beams (except the beams’ top face and the loading points), the beam-column connections and the lower columns. The fire test terminated after 74 min as soon as the tensile longitudinal steel bars of the upward-loaded cantilever beam attained the predefined critical temperature 530 °C. The lower columns exhibited partial concrete spalling and typical diagonal cracks appeared at the beam-column connections. Based on the recorded internal temperature distributions at the joint cores it was found that the material strength loss in the fire had insignificant impact on the load bearing mechanism of the joints. On the other hand, the gradual decrease in rotation capacity of the beam ends during the fire course considerably influenced the load-deflection relationship. A detailed numerical work has been carried out to simulate the response of the test specimens and will be published elsewhere.     

HRBF500级钢筋混凝土梁受火后力学性能试验研究

以HRBF500级钢筋混凝土梁为研究对象进行了常温下和受火后细晶粒钢筋混凝土梁的力学性能试验。在不同的受火时间作用下进行了5根细晶粒钢筋混凝土梁的明火试验,自然冷却至室温,然后进行静载试验。通过试验,观察其受火破坏现象、静载破坏形态和在不同工况下混凝土梁受火后剩余承载力的变化; 进行了2根细晶粒钢筋混凝土梁常温下的静载试验,得到荷载 挠度曲线关系,并与受火后的细晶粒钢筋混凝土梁剩余承载力进行比较。试验结果表明：高温对细晶粒钢筋混凝土梁的损伤很大,受火时间、配筋率、预加荷载对混凝土梁耐火性能有影响;受火时间越长,其剩余承载力越小;配筋率越小,其火灾后的剩余承载力越小;预加荷载降低梁的剩余承载力。     

以磷石膏为模壳的新型钢筋混凝土结构体系试验研究

提出了以磷石膏为模壳的新型钢筋混凝土结构体系。完成了以磷石膏为模壳的钢筋混凝土密肋网格式剪力墙模型试验和以磷石膏为模壳兼吊顶的钢筋混凝土密肋井字楼盖试验,试验结果表明,以磷石膏为模壳的钢筋混凝土密肋网格式剪力墙的受力特性与普通剪力墙类似,为弯曲破坏;以磷石膏为模壳兼吊顶的钢筋混凝土密肋井字楼盖在设计荷载作用下,结构具有较好的安全度,且用钢量、混凝土用量比常规结构小8.0%、7.5%。试验结果可为结构设计提供参考。     

城市隧道混凝土墙火灾行为数值模拟研究

为探究火灾作用下城市隧道混凝土墙的火灾行为规律,用有限元软件ABAQUS 建立三维混凝土墙数值模型,对其结构温度场分布进行数值模拟,分析得到墙体厚度、保护层厚度、火灾荷载比等因素对墙体变形的影响规律。结果表明：在火灾高温作用下,城市隧道混凝土墙受火面温度迅速升高,且由于混凝土的热惰性,内部会形成较大的温度梯度;混凝土墙体单面受火时的挠度变化规律可分为三个阶段,且火灾高温作用引起材料性能急剧劣化造成的截面中和轴偏移是影响墙体挠度变化的主要原因;混凝土墙体厚度、保护层厚度及火灾荷载比等因素对混凝土墙的火灾行为及其耐火性能均有一定影响,同时墙体挠度随火灾持续时间的增加而增大。     

钢筋再生混凝土结构研究进展及其工程应用

再生混凝土绿色、环保,是实现建筑垃圾资源化再利用的重要途径。为了进一步推动钢筋再生混凝土结构的研究发展与工程应用,分析了钢筋再生混凝土梁、板、柱、剪力墙、梁-柱节点及框架结构的受力性能、抗震性能、抗火性能、氯离子侵蚀后性能、徐变及抗冻性能的研究现状及存在的不足,列举了典型工程案例,指出了需要深化研究的问题。研究表明,钢筋再生混凝土梁、板、柱、剪力墙、梁-柱节点及框架结构的上述多数性能较同类钢筋普通混凝土构件(结构)的均有不同程度的劣化,但可通过合理设计实现其与普通混凝土相当甚至更好的性能,可用于实际工程中。     

受损剪力墙的非线性分析

砼剪力墙一种有效的抗偶力构件,成功地应用于各种抗震结构。但剪力侧向刚 大,地震时所承受的地震作用也较大,因此,在强地震作用下时常受损。本文作者采用钢筋砼非线笥有限元程序,对受损砼剪力墙进行了计算分析。计算模型考虑了钢筋和砼之间粘结－滑移,任意反复加载过程,砼开裂和裂缝闭合,裂缝宽度模拟。最后与试验结果进行了对比分析。     

箍筋锈蚀钢筋混凝土柱受火后抗震性能试验研究及有限元分析

为研究箍筋锈蚀钢筋混凝土柱的火灾反应及其火灾后的抗震性能,设计并制作4根尺寸及配筋相同的钢筋混凝土柱,以锈胀裂缝为损伤指标,对混凝土柱的箍筋进行电化学加速锈蚀试验,得到箍筋不同锈蚀率的混凝土柱.对RC柱进行限时受火试验,研究箍筋不同锈蚀率的混凝土柱的高温反应.对历经高温的钢筋混凝土柱进行低周水平反复荷载试验,并利用AN...     

Zur Tragfähigkeit von Ankerplatten in bewehrtem Beton

Load‐carrying capacity of anchor plates in reinforced concrete. For the load transmission into concrete constructions frequently anchor plates with welded studs are used. At the Institute of Structural Design two test series at reinforced concrete specimens were accomplished, which show that reinforcement decisively influences the load‐carrying capacity and the actually calculated design loads tend to underestimate the real resistance. On the basis of 27test results and supplementary FE analyses a first mechanical model based on the component method is presented, describing the load‐carrying capacity of anchor plates with welded studs in reinforced concrete elements.     

Whole-building behaviour of bonded post-tensioned concrete floor plates exposed to fire

This paper discusses the whole-building behaviour of post-tensioned concrete floor plates under fire conditions. Based on the results of eight fire tests on one-way spanning bonded post-tensioned concrete slab strips, recently conducted by the authors, a nonlinear finite element model was developed to model an entire typical concrete floor plate. The considered floor plate was post-tensioned using bonded tendons and was supported on traditional reinforced concrete columns. The overall objective of the study was to provide an understanding of the structural response and modes of failure of these floor plates under fire conditions. The mechanical and thermal material nonlinearities of the floor’s components, consisting of the concrete, grout, prestressing tendon, and the anchorages, as well as the reinforced concrete columns, have been considered in the model. The interface between the tendon and grout was also considered, allowing the bond behaviour to be modelled and the tendon to retain its profile shape during the deformation of the floor. The model has been validated against published finite element results on a floor plate under normal temperature conditions. The temperature distribution throughout the floor slab and supporting columns, together with the developed displacement and stress due to heating, and the overall fire resistance of the floor were predicted by the model. Furthermore, the variables that influence the structural behaviour comprising different natural fires, applied static load during fire, use of non-tensioned reinforcement, as well the difference between unbraced and braced frames were investigated in a parametric study. The study has shown that the failure mode of the floor under fire conditions is mainly due to tensile splitting along the tendons that extended to the top surface, while at ambient conditions the mode of failure is punching shear. The restraint provided by shear walls in the considered braced frame and the use of non-tensioned flexural reinforcement affected the vertical displacement behaviour under fire conditions, but did not affect the fire resistance due to the predicted tensile splitting failure mode. From the studies presented it is concluded that the design fire resistance of the floor specified in Eurocode BSEN1992-1-2 is acceptable, while that in the UK code BS8110 is unconservative and should be modified.     

粘钢加固钢筋混凝土剪力墙抗震性能试验研究

通过一组试验研究不同粘钢加固方式对钢筋混凝土剪力墙抗震性能的影响.本研究设计制作了6片钢筋混凝土剪力墙,并对这些试件进行了拟静力低周反复加载试验,这6个试件包括不经加固的混凝土剪力墙、只用水平U形箍加固的剪力墙、用水平U形箍和竖向钢材加固但端部锚固方式不同的剪力墙.在试验中记录了各试件在水平反复荷载下的荷载-位移滞回曲线、钢筋应变、墙体裂缝分布及墙体的破坏现象.分析了不同粘钢加固方式对混凝土剪力墙水平承载力、位移延性、耗能能力的影响.试验结果表明以粘钢加固的方式加固钢筋混凝土剪力墙,可以有效地改善剪力墙的抗震性能,并且,可靠的端部锚固方式对粘钢加固剪力墙的抗震性能也至关重要.     

Seismic behavior of RC coupled shear walls repaired with CFRP laminates having variable fibers spacing

The paper considers the seismic analysis of reinforced concrete (RC) coupled shear walls structures strengthened by bonded composite plates having variable fibers spacing. An efficient analysis method that can be used regardless of the sizes and location of the bonded plates is proposed in this study. In the numerical formulation, the adherents and the adhesives layers are all modeled as shear walls elements, using the mixed finite element method. Dynamic analysis was performed to investigates the influence of the fibers redistribution of the bonded plates on the lateral deflections of RC coupled shear walls. This conceptual study has demonstrated the feasibility of mitigating the seismic response of RC coupled shear walls building structures by using composites plates having variable fibers spacing.     

Reserved Strength of Reinforced Concrete Buildings with Masonry Walls

Abstract:   The case of a six-story reinforced concrete building that sustained the destruction of three columns is investigated. In this building, damage was limited to some cracks in the walls near the targeted zone. Other parts of the building remained intact. The building was analyzed using two different models. In one model, masonry walls were treated as nonstructural elements represented by applied loads. In the other model, walls were represented by membrane elements connected to concrete frames by link elements. Analysis was carried out for two cases, before and after damage. The study revealed that such buildings possess potential reserved strength. They have the ability to change their designated load path. The role of masonry walls is emphasized. In this case, masonry walls worked as a backup system that prevented major collapse of the building. It is estimated that, under normal conditions, masonry walls increase the building strength by 48%.     

江苏新长江(雅阁)国际酒店A塔楼高层混合结构体系特性分析

江苏新长江(雅阁)国际酒店中的酒店A塔结构高度为179.85m,属超高层结构。A塔楼采用了结构受力较好的钢管混凝土框架+钢筋混凝土核心筒的结构形式,此种混合结构方案也是现行超高层结构中最常见的结构形式。将混合结构方案与纯钢结构方案及钢筋混凝土结构方案从抗侧移刚度、延性、用钢量、耐久性和耐火性、施工速度及自重几个方面分别对比了三种结构方案的优缺点,对比发现,高层混合结构综合了钢结构和钢筋混凝土二者的优点,是一种非常可靠有效的高层建筑结构体系。高层混合结构框架与核心筒的竖向变形差较大以及框架与筒体的协调工作问题是高层混合结构需要解决的。     

某底框架商住楼在火灾中倒塌原因数值分析

采用计算机数值模拟方法研究了某钢筋混凝土底框架商住楼柱子的耐火稳定性。结果表明 ,该建筑的下部商业用房中火灾荷载和上部实际作用的重力荷载均较大是该建筑物于火灾中倒塌的主要原因     

Seismic performance of corrugated steel plate concrete composite shear walls

In this paper, composite shear walls with different encased steel plates (flat, horizontal corrugated, and vertical corrugated) were tested and simulated by Abaqus to investigate the seismic behavior of corrugated steel plate concrete composite shear walls (SPCSWs). The failure characteristics, deformation and energy dissipation capacity, and stiffness and bearing capacity of the structures under low‐frequency cyclic load were analyzed, and indexes of the seismic performance were obtained. The formulas of the shear‐bearing capacity of steel plate concrete composite shear walls are suggested, and the shear‐sharing ratio of each member is obtained. According to the obtained results, corrugated steel plates can bond with concrete well, and the bearing capacity of the vertical corrugated SPCSW are higher than that of the horizontal corrugated SPCSW. Compared with flat SPCSW, corrugated SPCSW has higher initial stiffness and lateral stiffness, better ductility and energy dissipation ability, and the degradation of bearing capacity and stiffness is slower. The shear‐sharing ratio of a steel plate is larger than that of reinforced concrete in the flat SPCSW and the vertical corrugated SPCSW, the shear force shared by steel plate and reinforced concrete in horizontal corrugated SPCSW is basically the same.