Abstract
The purpose of this paper is to determine a critical load for a nonuniform circular steel tube under eccentrically axial load. The circular tube has variable cross section at flattened ends with existing holes used for connection between members. Three different cases of eccentricities are studied with the drilled holes either on the same side or on the opposite side of column axis. The critical load is calculated from the differential equation of deflection curve which is solved by the power series and Runge-Kutta method. In addition, the loading tests were performed on a total of 180 specimens with different diameters, slenderness, and connection. The calculated results are compared and shown in a good agreement with those obtained from the experimental results. The results also show that the critical load decreases rapidly even at a small value of eccentricity and thus may have a significant effect on the load-carrying capacity.
Highlights
Space trusses have been widely used in engineering structures as construction industry imposing increasingly demanding requirements on safety design of light weight structures at low cost
The governing equation for loading of nonuniform circular column under eccentrically axial load is reduced to a differential equation of the fourth order which is solved by the power series and Runge-Kutta methods to calculate the critical load
The experiment with connecting holes located in a rod axis was performed
Summary
Space trusses have been widely used in engineering structures as construction industry imposing increasingly demanding requirements on safety design of light weight structures at low cost. The truss system is mainly composed of long steel members connected to each other at nodes to form the framework structures. The determination of critical load is essential to assess the reliability and safety of space truss structures. The steel members used in truss systems are generally in circular hollow section for their adequate behaviour under both tension and compression [1]. Various patented designs of connection mechanisms have been proposed for the space truss systems such as Triodetic, Nodus, Mero, Okta, “V”, processing of tube ends by milling and mutual welding, or connection and welding by a sheet insertion into the undercut tube ends [2, 3]
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