均布荷载作用下保温龙骨足尺墙体的抗弯性能

为研究腹板开孔的轻钢龙骨墙体在均布荷载作用下的抗弯性能,考虑腹板高度的影响,进行3.0 m×3.0 m足尺试件试验研究．分析了不同腹板高度的墙体在均布荷载作用下的破坏模式及腹板高度对墙体抗弯性能的影响．在此基础上,采用ABAQUS建立墙体的有限元模型,与试验结果进行对比分析,验证了有限元模型的可靠性．分析结果表明:石膏板可很好地限制竖龙骨的整体屈曲,当龙骨腹板高度为150 mm时,墙体竖龙骨在支座附近发生腹板剪切屈曲,同时在跨中位置发生畸变与局部屈曲的相关屈曲破坏;当龙骨腹板高度为100 mm时,墙体竖龙骨在跨中位置发生畸变与局部屈曲的相关屈曲破坏;当不考虑窗洞口影响时,腹板高度为100 mm的保温龙骨外围护墙体可满足我国全部地区建筑高度不超过50 m的城市建筑外围护墙体的抗风要求．     

Fire performance of cold-formed steel wall panels and prediction of their fire resistance rating

Recent research at the Queensland University of Technology has investigated the structural and thermal behaviour of load bearing Light gauge Steel Frame (LSF) wall systems made of 1.15 mm G500 steel studs and varying plasterboard and insulation configurations (cavity and external insulation) using full scale fire tests. Suitable finite element models of LSF walls were then developed and validated by comparing with test results. In this study, the validated finite element models of LSF wall panels subject to standard fire conditions were used in a detailed parametric study to investigate the effects of important parameters such as steel grade and thickness, plasterboard screw spacing, plasterboard lateral restraint, insulation materials and load ratio on their performance under standard fire conditions. Suitable equations were proposed to predict the time–temperature profiles of LSF wall studs with eight different plasterboard-insulation configurations, and used in the finite element analyses. Finite element parametric studies produced extensive fire performance data for the LSF wall panels in the form of load ratio versus time and critical hot flange (failure) temperature curves for eight wall configurations. This data demonstrated the superior fire performance of externally insulated LSF wall panels made of different steel grades and thicknesses. It also led to the development of a set of equations to predict the important relationship between the load ratio and the critical hot flange temperature of LSF wall studs. Finally this paper proposes a simplified method to predict the fire resistance rating of LSF walls based on the two proposed set of equations for the load ratio–hot flange temperature and the time–temperature relationships.     

推出试件中剪力钉剪切刚度实测与计算方法

剪力钉的剪切刚度是钢-混凝土结构设计和计算中的一个重要参数,一般通过分析剪力钉模型试验的实测结果得到.剪力钉的剪切刚度是个综合且复杂的量,缺乏统一的取值标准和计算方法.根据剪力钉推出试验的测试结果,综合欧洲规范4条文和学者推荐的计算方法,分析得到了φ22×200剪力钉在界面无摩擦组合结构中纯剪下的剪切刚度值,并对相关影...     

Resistance of headed studs subjected to fatigue loading: Part I: Experimental study

In steel-concrete composite structures the transfer of longitudinal shear forces at the interface between steel and concrete is mostly realized by headed shear studs. Especially in bridges due to traffic loads these shear connectors are subjected to high-cycle loading and the fatigue resistance governs the design. In this first part of two companion papers a series of experimental work with standard EC4 push-out specimens is presented. The main purpose of these tests was to determine the fatigue life and a possible reduction of the static strength of the headed shear studs subjected to unidirectional cyclic loading. A further aspect was to examine the effects of the loading sequence and damage accumulation on the fatigue life. The results of the experimental investigations show that due to a crack initiation at the stud foot at 10%-15% of the fatigue life, an early reduction of the static strength is caused. Furthermore tests to examine the effects of the loading sequence on the fatigue life revealed that the linear damage accumulation hypothesis according to Palmgren and Miner on which the present design codes are based do not describe the real behaviour.     

Effect of Different Connectors on Concrete Composite Box-Girders with Corrugated Steel Webs

不同剪力连接键对波形钢腹板PC组合梁力学性能影响

逯彦秋^1,2

(1.北京首都公路发展集团有限公司, 北京 100161;

2.清华大学 土木工程系,北京 100084)

创新点说明：

首次提出并通过实验方法研究了PBL剪力连接键、栓钉剪力连接键对波形钢腹板PC组合梁极限承载力、抗弯刚度、抗裂性、预应力导入效率的影响;

研究目的：

为明确波形钢腹板PC组合梁常用的两种剪力连接键（即PBL剪力键、栓钉剪力键）对波形钢腹板组合梁极限承载力、刚度、抗裂性及预应力导入效率等力学性能的影响,从而为该类型梁设计中正确选择合适的剪力连接键提供技术支持。

研究方：

采用实验结合有限元方法

结果：

PBL剪力键在提高波形钢腹板PC组合梁的极限承载力、抗弯刚度、抗裂性等反面优于栓钉剪力键,但是在梁的预应力导入效率方面不如栓钉剪力键。

结论：

在波形钢腹板PC组合梁设计中应根据梁的不同受力特点选择不同的剪力连接键,不可主观臆断地选择剪力连接键,为该类型桥梁留下安全隐患。

关键词：栓钉; PBL剪力键;极限承载力;预应力导入效率;抗弯刚度;抗裂特性

     

Seismic behavior of connections composed of CFSSTCs and steel-concrete composite beams — finite element analysis

Based on the experimental results of connections composed of concrete-filled square steel tubular columns (CFSSTCs) and steel-concrete composite beams with interior diaphragms, exterior diaphragms, or anchored studs, 3-D nonlinear finite element models were established to analyze the mechanical properties of these three types of connection using ANSYS. Finite element analyses were conducted under both monotonic loading and cyclic loading. The load-displacement and shear force-deformation curves of the finite element analyses are in agreement with those of the tests in terms of strength and unloading stiffness. Parametric analyses were conducted on the connections with exterior diaphragms under monotonic loading to investigate the influences of axial load ratio, width to thickness ratio, and dimensions of exterior diaphragms on the connection behavior. It was found that the strength and stiffness are less influenced by the axial load ratio and the dimensions of the exterior diaphragms, but more influenced by the width to thickness ratio of the steel tube under shear failure mode.     

锈蚀栓钉连接件力学性能试验研究

为了解钢-混组合梁的栓钉连接件发生锈蚀后的静力工作性能,进行了4组栓钉试件的推出试验.首先通过人工电化学快速锈蚀方法使试件中的栓钉达到预定锈蚀状况,然后进行静载破坏试验,通过试验结果分析不同锈蚀状况对栓钉连接件力学性能的影响.结果表明:栓钉钉杆尤其是靠近结合面处发生锈蚀时,其极限承载力降低最大达到18％,相同荷载作用下滑移量增加,与极限荷载相对应的滑移量最大减小了12％;栓钉大头端部发生锈蚀时,对推出试件的承载力影响不大,但对栓钉连接件变形性能影响较大.     

浅析一种双头螺柱拆卸工具

阐述了一种双头螺拄拆卸工具的基本结构及工作原理,同时提出使用该工具的注意事项。在不容易拆卸双头螺柱的场合。应用双头螺柱拆卸工具灵巧的特点,可更好地提高生产效率。