IN-PLANE ELASTIC STABILITY BEHAVIOR OF SPATIAL CIRCULARTRUSS-ARCH

摘要

Truss-arch structures have found wide application in spatial large-span steel structures and bridges because ofrnbeautiful appearance, good load-carrying capacity, economy and practicality. A spatial circular truss-arch with arnsymmetric triangle cross section, composed of one bottom chord and two top chords, is generally used as roofrntruss in building structures. Its in-plane elastic stability behavior is studied in this paper. Firstly, a briefrnintroduction has been given to instability characteristics of truss-arches and engineering application in buildingrnstructures. Secondly instability types are presented according to instability behavior under different loading typesrnand initial geometric imperfection distribution along the arch axis. Based on the classical stability theory of archrnstructures, several typical buckling modes are fully discussed, and especially a secondary bifurcation bucklingrnmode of truss-arches is investigated theoretically, which usually controls the design of truss-arch structures.rnThirdly, by employing the finite element analysis from a well-known FEA soft package ANSYS, in-plane linearrnand nonlinear buckling behavior and elastic ultimate load-carrying capacity of truss-arch structures are analyzed.rnThen the overall stability behavior of truss-arch structures is studied from the complete loading-displacementrncurves obtained from numerical analytical results. The effects of parameters such as rise-to-span ratio, height ofrncross section, span length and dihedral angel of diagonal rods on the in-plane elastic stability of truss-arches arerninvestigated systematically. Two types of loads are considered: one vertical load uniformly distributed on arnhorizontal projection, and the other vertical load uniformly distributed along the arch axis.