悬伸梁和双跨连续梁的整体稳定承载力试验研究

为了研究悬伸梁和双跨连续梁在集中荷载作用下的整体稳定性能,对两种单轴对称截面形式(上翼缘加强、下翼缘加强)、两种悬伸长度(1200mm、1600mm)共计5根悬伸梁,以及一种单轴对称截面形式(上翼缘加强)、三种相邻跨度之比(1∶0.48、1∶0.64、1∶1)共3根双跨连续梁进行了试验研究。在进行破坏试验前,对悬伸梁进行了三种荷载作用位置的弹性试验,对连续梁进行了三种加载比例的弹性试验,并利用Southwell法确定了临界荷载。试验研究结果表明:当最大弯矩出现在悬伸梁的简支跨且上翼缘受压时,上翼缘加强构件稳定承载力明显高于同尺寸的下翼缘加强构件;悬伸长度为1600mm的构件承载力明显高于悬伸长度为1200mm的构件承载力;荷载作用在简支梁段跨中时构件稳定承载力最低,荷载作用点离中间支座越近构件稳定承载力越高。双跨连续梁中,在等比例加载时,相邻跨度之比越大,构件稳定承载力越高。此外,对试验进行了有限元模拟,计算结果与试验结果吻合良好。

Experimental investigation on overall stability capacity of overhanging beams and two-span continuous beams

In order to investigate the overall stability of overhanging beams and two-span continuous beams under concentrated loading,a total of 5 overhanging beams with two singly symmetric sections(top flange strengthened、bottom flange strengthened) and two different overhanging lengths(1200mm、1600 mm) were tested.In addition,3 two-span continuous beams with one singly symmetric section(strengthened top flange) and three different length ratios(1∶0.48、1∶0.64、1∶1) were tested.Before the failure tests,a series of elastic tests were conducted on overhanging beams considering three loading positions and continuous beams considering three load ratios.The critical loads were determined using Southwell Plot method.It is found that when the top flange is compressed and the maximum bending moment appears in the supported segment of overhanging beam,the buckling loads of the members with top flange strengthened are significantly higher than the members of the same size with bottom flange strengthened;the capacities of members with the 1600mm overhanging length are obviously larger than 1200mm overhanging length;when the load is applied at the central section of the supported segment,the critical load is the lowest.As the loading position moves closer to the middle support,the critical load is greater.When the load ratio is held constants at 1,the stability capacity of the continuous beams is greater,with the length ratio increased.Furthermore,tests are simulated by finite element analysis.Results from the analysis agree well with experimental data.