Experimental And Theoretical Study In Ultimate Load Capacity Of High-Strength Single-Angle Compression Members

As the development of electric power industry in our country, both of the transmission towers and their load-carrying capacities are getting much larger. If the design load is large, the method of built-up sections is accepted to meet the bearing capacity requirements; as a result, the quantity of transmission tower members and the difficulty of the joint splicing are both increased, which wastes the material and the power. In order to improve the cost effectiveness of towers, the high strength steel is required urgently. Without the method of built-up sections, the usage of high strength steel still can reduce the tower weight and construction difficulty as well as to fulfill the strength design requirement.This paper is based on the experiment of Q460 high-strength single-angle equal-leg compression members with a concentric load at one end and normal framing eccentricity at the other end. According to different sections and slenderness ratios, the test specimen is divided into sixteen groups. And each group consists of three sections of the same size specimen. The slenderness ratios of test specimens are 30,45,60 and 80,respectively. In addition,the sizes of angles are L125×10,L140×12,L160×10 and L160×12.After analyzing the experiment, the finite element software ANSYS is used to simulate the experiment and the comparative analysis is also conducted between the experiment results and the simulation results, which proves the feasibility and validity of the finite element analysis. Then, parametric analysis is done in order to examine the impacts of several factors such as initial bending, Young's modulus of elasticity, the gusset plate thickness and slenderness ratio, meanwhile some design suggestions are also given in this paper. Furthermore, based on ANSYS, the ultimate load carrying capacities of compression members with different slenderness ratios are obtained and the width-to-thickness ratios of these compression members are all within the ASCE10-97 limit. Finally, according to the comparison between the experiment results, the finite element analysis and calculation results which obtained by ASCE10-97 Manual formula method, some advices are proposed for slenderness ratio equation of single-angle equal-leg compression members loaded through one leg. Likewise, these advices apply to DL/T5154-2002.The conclusions reached by the research are as following:In project, the initial bending limitation for moderate and small members can be extended to L/250; for long members, the limitation should be limited to no more than L/1000. When the gusset plate thickness to angle width ratio is no more than 0.2, the thickness of plate has less impact on bearing capacity; when the ratio is more than 0.2, the impact increased obviously. Gusset plate unconnected length, Young's modulus of elasticity and residual stress have slight effects on bearing capacity. ASCE 10-97 method for the Q460 high-strength single-angle equal-leg compression members has not a reasonable degree of accuracy, which underestimates ultimate load capacity of long members.