土木工程专业英语课件作者陈瑛5.2AxiallyLoadedMembers.pptVIP

5.2 Axially Loaded Members Characterisitics of Axially Loaded Members Tension Members Applications Tension chords and internal ties in trusses Tension bracing members Hangers supporting floor beams Sections Open sections – angles, channels, tees, … Closed sections – circular, square, rectangular hollow sections Compound and built-up sections – double angles/channels, … Round bars, flats and cables Factors affecting efficiency of tension members End connections Reversal load may cause buckling Resisting moment Compression members Applications Generally described by terms ‘columns’ or ‘struts’ Vertical members supporting floors, roofs and cranes … Most members are also subjected to moment besides axial load Sections Tend to be stocky with square sections – resist buckling Rolled, compound and built-up sections H-section – used in buildings where axial load predominates Single angles, double angles, tees, channels and hollow sections – trusses, lattice girders and bracing Design Considerations Tension members Possible failure modes Yield in gross section Fracture in effective net section Block shear Shear rupture along plane through fasteners Bearing on fastener holes Prying Compression members Possible failure modes Yielding Inelastic/elastic buckling – flexural, torsional, and flexural-torsional Flexural – doubly symmetric or antisymmetric cross-sections; or singly symmetric sections (buckled about an axis that is perpendicular to the axis of symmetry). Torsional – doubly symmetric sections with very thin walls Flexural-torsional – singly symmetric cross-sections (buckled about the axis of symmetry); or unsymmetric cross-sections. Local buckling – width thickness ratio Design Details for Columns Choice of column cross-section Column construction Beam-column connections Beam cap connections Column splices Not prepared for full contact in bearing, designed to transmit all moments and forces Prepared for full contact, provide continuity of stiffness about both