大宽厚比H形截面短柱轴压性能研究

Study on behavior of H-section axially compressed stub columns with large width-thickness ratio

针对大宽厚比H形截面轴心受压构件,目前中国GB 50017—2017中尚未形成完整的设计方法,而在欧洲EN 1993-1-1和美国ANSI/AISC 360-16中未能充分考虑板件相关作用的影响。为确保此类构件在工程应用中的安全性,探讨以上规范计算方法的适用性,针对12个大宽厚比,即宽厚比超出GB 50017—2017板件宽厚比限值的H形截面短柱,开展了轴压试验研究,基于试验结果进行了有限元分析。研究结果表明:翼缘与腹板间的约束作用在不同宽厚比组合下存在差异,直接影响板件的屈曲荷载,进而影响构件的承载力;通过调整翼缘与腹板宽厚比组合,大宽厚比H形截面轴心受压短柱有较高的屈曲后承载力,甚至可以达到全截面塑性承载力;根据板件宽厚比相对大小不同,峰值荷载后大宽厚比H形截面轴心受压短柱荷载-位移曲线可分为有、无陡降段两种类型;通过有限元分析,得到了宽厚比对H形截面轴心受压短柱承载力的基本影响规律,提出了考虑板件相关作用的受压截面分类宽厚比限值;通过对不同规范轴心受压构件承载力计算结果的对比,发现欧洲EN 1993-1-1和美国ANSI/AISC 360—16对H形截面轴心受压短柱承载力的计算结果偏于不安全。

Complete design method for axially compressed stub columns with large width-thickness ratio is not available in Chinese code GB 50017—2017,and the effects of flange-web interaction were not sufficiently taken into account in the existing calculation methods in EN 1993-1-1 and ANSI/AISC 360-16.In order to ensure the safety of slender section members in engineering applications and to evaluate the applicability of the above specification calculation methods,axial compression tests were carried out on 12 welded H-section stub columns with large width-thickness ratio whose width-thickness ratio also exceeds the limit values of GB 50017—2017,and extensive parametric analysis was conducted based on the test results.The results show that the restraining effect of the plates varies with the width-tothickness ratio combinations of the flange and the web,which directly affect the buckling load of the plates and the bearing capacity of the member.By adjusting the width-thickness ratio combinations of the flange and web,the axially compressed slender H-section stub columns can have a strong post-buckling bearing capacity,where even a full-section plastic bearing capacity can be reached.With different width-thickness ratios of the plates,the load-displacement curves of the axially compressed slender H-section stub columns after the peak load can be divided into two types,i.e.,with or without steep drop stages.Based on the validated finite element model,the influence of the widththickness ratio on the bearing capacity of axially compressed H-section stub columns was revealed,and classification limits of compression sections considering the plate interaction effect were proposed.The calculation results of the bearing capacity of axially compressed members of different codes were compared,and it was found that the calculation results of EN 1993-1-1 and ANSI/AISC 360-16 for the bearing capacity tend to be unsafe.