Numerical analysis of truss systems with stiffened flattened end-bars

Abstract

Circular hollow sections are usually used in long-span roof truss systems. One of the typology for connecting elements in such structures involves the flattening of bar ends. This article presents the numerical analysis of a plane truss composed of circular hollow sections, in which diagonal bars have flattened ends. In this sense, a new flattening typology called stiffened flattening is proposed, characterized by a non-flat geometry, with the creation of stiffeners in the lateral edges of the diagonal flattened ends. The diagonal connecting system with the chord members uses connecting plates. The plates are welded to the chords and the diagonals are connected to latter through a single bolt. The numerical analysis using finite elements method was developed in two stages through ANSYS software with the Parametric Design Language APDL , in which parameters such as geometry, materials, element types, boundary conditions and loads are specified. A non-linear analysis was performed using shell elements on the chords, diagonals, plates and welds, and contact elements between the diagonals with stiffened flattened ends and the connecting plates. Initially, a numerical study of the connecting node and the stiffened flattened end was performed, and the results directed the modeling of the plane truss. The numerical results were calibrated with the experimental truss results in full scale. The numerical result of the plane truss was also compared to a theoretical study, considering the axial load eccentricity applied in the diagonal with stiffened flattened ends. The study was based on the consideration of combined effects of axial force and bending moment provided by the Brazilian standard ABNT NBR 8800:2008. The final results indicate that the numerical model proposed is efficient and has good correlation with the experimental and theoretical results.

Numerical analysis of isolated end-flattened steel bars under compression in space trusses

“…The Brazilian standard of circular hollow sections ABNT NBR 16239:2013 [26] presents prescriptions for the determination of the axial compression strength of calculation for prismatic bars. It is emphasized that the standard provides resistance capacity without regarding the bars flattened-ends and eccentricities [30]. ABNT NBR 16239:2013 [26] considers that the sizing of bars under compression load must be carried out in accordance with the requirements of ABNT NBR 8800:2008 [31].…”

“…ABNT NBR 16239:2013 [26] considers that the sizing of bars under compression load must be carried out in accordance with the requirements of ABNT NBR 8800:2008 [31]. However, it presents its own curve to calculate the reduction factor associated with the axial compression load for tubular profiles [30]. Thus, the computation of the axial compression strength of calculation given by:…”

Experimental study and finite element analysis of heavy-duty escalator truss under full load conditions

“…Zhou et al investigated the response of an 8-story steel staggered-truss system, utilizing a scaled model at 1/8th size subjected to reversed low cyclic loading, and put forward some suggestions for the design of a staggered-truss structure 2 . Amélia et al created a new flattening typology by incorporating stiffeners in the lateral edges of the diagonal flattened ends, and found that this stiffened flattening technique can simplify the structural design of the plane and multi‐planar trusses 3 . To replace traditional reinforcement methods for coupling beams used within shear wall system, Chairunnisa et al modeled a simplified version of a coupling beam using steel truss configurations made from steel angle profiles and found that this kind of steel truss-coupling beam can show fairly well behavior under lateral load 4 .…”

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

“…There are high concentrations of stress on the nodal region, separation and slip between bars, which can sensibly increase the loss of bearing capacity with the emergence of bending moment [4,11,16]. (c) The eccentricities in the connections can cause increases of stress for a reduced nodal stiffness [17,18]. Another characteristic worth emphasizing refers to the collapse of special trusses with typical joints, which occurs because of the collapse of the connection with inefficient use of the bar's strength capability [19].…”