偏心受压单角钢构件力学性能试验研究

Experimental study on mechanical behavior of single angle under eccentric compression

为了研究单边连接角钢在输电铁塔斜杆中的受力性能,采用与肢边平行的刀口铰支座,对48根等边角钢与62根不等边角钢试件进行了偏心受压试验稳定承载力研究。分析了节点板厚度、螺栓数量对其承载力影响,考察了不同长细比时角钢的破坏模式、承载力及其变形形态,并与国内外规范中局部稳定宽厚比限值进行了比较。研究结果表明：长细比小于35的等边角钢与长细比小于40的不等边角钢发生了局部屈曲破坏,反之发生整体屈曲破坏,其中包括弯曲屈曲与弯扭屈曲两种;角钢承载力随着偏心距增加而逐渐下降,当等边角钢长细比超过175或者不等边角钢长细比超过150时,偏心对承载力的影响可忽略;当长度相同时,等边角钢承载力略高于不等边角钢,二者差值随长细比增加而减小;随着长细比增加,角钢弯曲轴从肢边平行轴逐渐向弱主轴转动,其稳定系数相较于规范值来说时高时低,承载力应根据实际弯曲轴对应的长细比进行确定。该类角钢构件局部稳定宽厚比限值应低于我国现有规范GB 50017—2017与DL/T 5154—2012的规定值。

In order to study the mechanical properties of the steel single angle attached by one leg in transmission tower, a total of 48 steel equal-leg angle and 62 unequal-leg angle specimens were tested on knife-edge bearing which is parallel to the leg of angle. The effects of gusset plate thickness and bolts number on bearing capacity were analyzed. The buckling modes, ultimate bearing capacity and deformation performance of the steel angle were investigated and compared with various codes. According to the test results, the buckling modes are local buckling when slenderness ratio is less than 35 for equal-leg angle and 40 for unequal-leg angle, otherwise the buckling modes are mainly flexural buckling or flexural-torsional buckling. It also shows that an increase in eccentricity results in a reduction in ultimate load. However, the effect of eccentricity could be ignored when the slenderness ratio is more than 175 for equal-leg angle or 150 for unequal-leg angle. The bearing capacity of equal-leg angle is larger than that of unequal-leg angle with the same length, and the difference decreases with the increase of slenderness ratio. The bending axis of specimen moves from parallel axis to minor axis as the slenderness ratio increases. The stability coefficients from test results are higher or in some cases are lower than those from the codes, so that the bearing capacity should he calculated by the practical bending axis. For the angle steel on knife-edge bearing, the limit of the plate width-thickness ratio should be less than that in GB 50017-2017 and DL/T 5154-2012.