焊钉连接件抗拉承载力试验研究

为建立组合结构桥梁常用焊钉连接件的抗拉承载力计算方法,进行了高度分别为100、200、300和400mm的焊钉连接件抗拉承载性能模型试验,比较分析了高度对破坏模态、承载力和峰值分离的影响;基于国内外93个模型试验结果,比较分析了ACI 318-08、PCI 5th和CEB-ECCS等标准所建议抗拉承载力计算式与试验结果的吻合度;给出了防止焊钉拔出、边缘混凝土压裂和混凝土掀起等脆性破坏的限制条件;结合脆性破坏限制条件和延性破坏抗拉承载力计算式提出了焊钉连接件延性破坏抗拉承载力计算方法.研究结果表明:焊钉受拉延性破坏时的承载力和峰值分离约为脆性破坏时的1.5和5.8倍;ACI 318-08所建议计算式与试验结果吻合度较高;分别采用混凝土强度等级、焊钉缘端距离及焊钉高径比作为限制条件,能够防止焊钉受拉时发生脆性破坏;提出的焊钉连接件延性破坏抗拉承载力计算方法,可为焊钉连接件的延性设计提供参考.

Experimental study on static behavior of headed studs under tension force

In order to develop the calculation method for the tensile strength of headed studs widely used in steel concrete composite bridges, four groups of pull out specimens with different stud heights were tested. The overall stud heights used in the four groups were 100, 200, 300 and 400 mm, respectively. Based on the test results, the effect of stud height on failure mode, tensile strength and peak separation were investigated. Tensile strength equations specified in exiting codes (ACI 318 08, PCI 5th and CEB ECCS) were evaluated based on 93 test data of this study and other researches. In addition, constraint equations for preventing the brittle failure modes of stud pullout, side face blowout and concrete breakout were developed. Finally, calculation method of the ductile tensile strength of headed studs was proposed. The results indicate that the tensile strength and peak separation of the specimens failed due to steel failure are 1.5 times and 5.8 times as large as those of the specimens failed due to concrete breakout failure, respectively. The strength equations given by ACI 318 08 give more accurate predictions than those in the other codes. The minimum concrete compressive strength, minimum distance from stud center to concrete edge and stud height diameter ratio are employed as constraints to prevent the brittle failure modes. The proposed calculation method of the ductile tensile strength of headed studs can provide guidance when designing headed studs under tension force.