Static Behaviors and Applications of Buckling Monitoring Members with Rigid Ends

The buckling of compression members may lead to the progressive collapse of spatial structures. Based on the sleeved compression member, the buckling monitoring member is introduced to control the buckling of compression member and raise buckling alert by sensing contact between the core tube and the restraining tube. Considering the rigid connection among the members in spatial structures, the buckling monitoring member with rigid ends needs to be further analyzed. An experimental test was conducted and finite element analyses were performed with calibrated finite element models. The results indicated that the ultimate bearing capacity and post-ultimate bearing capacity of the core tube were enhanced due to the restraint from the restraining tube. The contact was successfully sensed by pressure sensor, revealing that it sensed the buckling of the core tube. Parametric studies were conducted, indicating that the core protrusion, core slenderness ratio, the gap between the core tube and restraining tube, and the flexural rigidity ratio are the key parameters affecting the bearing capacity and the failure modes of the buckling monitoring member, and some key values of parameters were proposed to obtain good bearing capacity. Based on the parametric studies, the failure modes of buckling-monitoring members are summarized as global buckling and local buckling. The stress distribution and deformation mode of buckling monitoring members are presented in the non-contact, point-contact, line-contact, reverse-contact and ultimate bearing state. The buckling monitoring member is applied in a reticulated shell by substituting the buckling members. It can effectively improve the ultimate bearing capacity of reticulated shell.

BEARING CAPACITY OF SINGLE-ANGLE COMPRESSION MEMBER: EXPERIMENTAL AND NUMERICAL INVESTIGATION

This study was conducted to investigate the load-bearing capacity of a single angle column under various loading conditions to determine the loading condition offering the highest load- bearing capacity. In all cases, the load is transferred through one leg (or two legs) of the angle which has a smaller cross-sectional area compared to the total area of the angle profile. The main objective of this study is to develop almost all of the possible support conditions for the single angle section and carry out laboratory tests on the chosen specimens to determine the most suitable one. Also, there are some finite element investigations done using ABAQUS software to find out the maximum forces in which all the elements of the structures remain their linear behavior and the stress spots concentration. Based on the obtained results, it is possible to increase the axial critical load of a single angle by using the connections at the main axis of the section.

Analytical study of the seismic performance of all-steel buckling-restrained braces with H-shaped cores

The seismic performance of an H-shaped core buckling-restrained brace (HBRB) is evaluated through detailed finite element analysis. The numerical model is validated against available experimental data and a parametric study is carried out to investigate the effect of influential parameters on the cyclic behavior and failure modes of HBRB. Several design parameters including the yielding length ratio, the constrained length, the presence of stiffeners and their thicknesses, the length of the transition region and the gap size are considered in the parametric investigation. Based on the analysis results reducing the yielding length of HBRB increases its post-yield stiffness and the axial strain and stress of the H-section core. Since buckling of the unconstrained region was observed in HBRBs with insufficient stiffener thickness, an analytical method is proposed for evaluating the sufficiency of stiffeners by estimating the critical buckling load of HBRB as a three-segment stepped compression member.