Experimental and Numerical Analysis for Eccentricity Solution in Double-Layer Space Truss

Abstract

This paper shows an extensive study on the Typical Connections used in Double-Layer Space Truss. For this structural system, the ends of the bars are flattened to connect the bars. However, the flattening process results in a highly plastic stamping zone susceptible to warping with the appearance of two eccentricities, one of which causes rotation of the connection, with the presence of a bending moment with local rupture resulting in progressive collapse of the entire coverage system, as already evidenced in several countries. Therefore, eccentricity in this paper is studied and an analytical solution to the problem is presented through the use of a new device called a spacer. Furthermore, a preliminary study with complex numerical simulation was carried out with nonlinear analysis in ABAQUS were evaluated. For this study, nine space trusses were experimentally tested with reinforcement spacer in reduced trusses. After confirming the efficiency of the spacer proposal, another six space trusses were tested in the laboratory, this time, on a full-scale. In this study, two types of spacers were evaluated, one made of USI SAC 350 steel and another cheaper one made from recycled tires from heavy vehicles with multiple filaments of steel and nylon wires in the rubber layers. The two devices presented very close resistance capacity values, with a resistance gain of approximately 30% in relation to connections without reinforcement, with structural failure characterized by buckling of the bars. Finally, a numerical study of space trusses with spacers was developed. In practical design terms, from these FE simulations it was possible to determine the normal stresses for different spacers applied in the different modeled spans.