Performance evaluation of demountable shear connectors with collar step at ambient and elevated temperatures
Performance evaluation of demountable shear connectors with collar step at ambient and elevated temperatures
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DOI：
10.1016/j.engstruct.2019.05.059
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发表时间：
2019-09
影响因子：
5.5
通讯作者：
R. Sencu;Yong C. Wang;J. Yang;D. Lam
中科院分区：
文献类型：
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作者：
R. Sencu;Yong C. Wang;J. Yang;D. Lam
本文介绍了一种新型组合剪力连接件的试验结果，该连接件可用于建造可拆组合楼板。共进行了21次推出试验，以量化不同设计参数的影响，包括不同的标称温度水平（20°C、100°C、300°C、450°C、600°C），钢桥面板垂直和平行于钢截面，两种不同的嵌入式剪力钉长度和两种不同等级的混凝土（C40/50和C20/25）。试验主要在稳态条件下进行，其中将试样温度升高至所需目标，然后施加载荷直至试样失效。还进行了一些瞬态试验，其中施加的载荷等于600 °C下稳态试验的承载能力，然后增加试样温度直至失效。观察到三种模式：（i）混凝土破碎与螺柱断裂，（ii）螺柱断裂和（iii）混凝土拔出。混凝土等级为C20/25的试件仅发生混凝土拔出。研究发现，在不超过400 °C的高温下，混凝土的破坏主要是由混凝土的破碎引起的，同时也产生了延性螺柱的破坏。在高于400 °C的高温下，失效模式变为剪切螺柱断裂。欧洲规范4的计算公式表明，产生的剪力连接件阻力与高等级混凝土的稳定状态结果合理一致，即使之前的公式是针对焊接剪力钉开发的。瞬态试验在低于目标温度600 °C的温度下失败，表明在高温下使用稳态试验评估剪力连接件的抵抗力可能不安全。
This paper presents the results of an experimental programme to investigate the performance of a new composite shear connector that can be used to build deconstructable composite floors. A total of21push-out tests were conducted to quantify the effects of different design parameters, including different nominal temperature levels (20°C, 100°C, 300°C, 450°C, 600°C), with the steel decking perpendicular and parallel to the steel section, two different embedded shear stud lengths and two different grades of concrete (C40/50and C20/25). The tests were mainly carried out under steady-state condition where the specimen temperatures were increased to the desired target and the load was then applied until failure of the specimen. A few transient tests were also carried out, in which a load equal to the load carrying capacity of the steady-state test at600°C was applied, followed by increasing the specimen temperature until failure. Three modes were observed: (i) concrete crushing with stud fracture, (ii) stud fracture and (iii) concrete pull-out. Concrete pull-out occurred only on one specimen with concrete gradeC20/25. It is found that the main failure mode at elevated temperatures not exceeding400°C was initiated by concrete crushing, concomitantly producing ductile stud damages. At elevated temperatures above400°C, the failure mode changed to shear stud fracture. The Eurocode 4 calculation equations were shown to produce shear connector resistances to be in reasonable agreement with the steady state results for the higher-grade concrete, even though the previous equations were developed for welded shear studs. The transient state tests failed at lower temperatures than the target temperature of600°C, indicating it may not be safe to use steady state tests for evaluation of shear connector resistance at high temperatures.