拉条和屋面板联合作用下檩条的屈曲性能研究

THE RESEARCH ON BUCKLING PROPERTIES OF PURLIN WITH THE COMBINED EFFECTS OF ANTI-SAG RODS AND ROOF PANEL

钢结构屋盖系统中檩条的跨度通常较大,在弯矩和轴力作用下容易发生屈曲。其稳定性通过两个方面来保证,一方面与之相连的屋面板为其提供均布的弹性约束,另一方面在檩条的腹板位置设置拉条来维持屋面系统的稳定性,相当于在檩条跨中侧面附加了一个弹簧,提供其侧向稳定。建立屋盖系统中檩条的隔离模型,分析檩条在屋面板和拉条联合作用下屈曲荷载的提高程度,验证了拉条能够对檩条稳定性起实际作用,但存在一个门槛刚度,当拉条的约束程度增加使檩条刚度达到此刚度后,再增加拉条约束对檩条的临界荷载的提高没有任何作用。此结论可为檩条和拉条稳定性设计提供理论依据。

The span of a purlin in steel roof system usually being designed as the large one, is easily to buckle under the combined action of bending moment and axial force. The stability is guaranteed through two aspects., one is that the purlins connect with roof panel through self-tapping screws, so the roof cladding exerts uniformly distributed flexible constraints on purlins. On the other hand, the anti-sag rods are set at the web of purlin in order to maintain the stability of the roof system, which is equivalent to adding centralized spring at the midspan of the purlin. It was established an isolation model for purlin in roof systems, and analysed the improvement degree of buckling load. It was also verified that the anti-sag rods play a practical role in improving stability of purlin. However, when the constraints of anti-sag rods reach a certain level, a further increase in the constraints of anti-sag rods has no effect on improving of critical loads, so that there is a threshold stiffness. The conclusion can provide a theoretical basis for the design of anti-sag rods and purlin.