异型钢管塔柱承载力试验研究和有限元分析

Experimental study and FE analysis on special steel tube column for Henan Broadcast and TV Tower

河南广播电视发射塔外塔柱采用异型大直径钢管,截面由三段直边和三段圆弧板组合而成,其径厚比已超过现行《钢结构设计规范》对圆钢管径厚比的限值,其承载力与管壁不同的加劲方法有关。分别采用内加劲肋和内桁架加劲两种方法对管壁进行内加劲可提高管壁的局部稳定性,从而提高构件的极限承载力。通过对两种加劲方法以及无加劲肋三种类型截面塔柱的缩尺试验研究和有限元模拟分析,有限元计算结果与试验实测结果吻合较好。研究表明:设计荷载作用下,三种形式截面均全截面处于弹性工作状态,具有足够的强度和刚度。对管壁采用内加劲肋方式处理后,截面承载能力提高20%左右,采用内桁架对管壁进行处理也可改善截面的应力分布,但在设计荷载作用下的效果并不显著。建议设计中采用内加劲肋对管壁加劲,提高构件的安全储备。

Special and large-diameter steel tubes are adopted as external columns in the Henan Broadcast and TV Tower. The special welded steel tube is coiled and welded by three plates and three arc plates. The diameter-tothickness ratio of this special steel tube exceeds that specified by ＇ Code for design of steel structures＇ and its bearing capacity depends on the difference of stiffening method inside tube wall. Through the internal stiffened plate or truss, the local stability of tube wall can be increased, and so does the ultimate bearing capacity. The reduced-scale test and finite element analysis about three kinds of stiffened sections including truss, ribbed plate and unribbed plate were carried out. The comparison shows that the experimental data coincide with finite element calculating results. The present investigation indicates that three types of sections subjected to the design loads have sufficient strength and rigidity. The hearing capacity of the special steel tube column can be improved at least about 20% with rib stiffener. The effect of stiffening truss is unapparent though the stress distribution on tube wall is further reasonable. The suggestion on rib stiffener adopted in column is proposed with the safety coefficient is heightened.