Experimental Study On Bearing Capacity And Failure Mechanism Of Composite Steel Staggered Truss Structures

The steel staggered truss system is a new concept in structural steel framing for high-rise buildings.It has been introduced into our country since last 90's,but used very rarely due to the lack of seismic study.So this paper was mainly aimed at the seismic behaviors of a composite steel staggered truss structure under cyclic loading.In this paper,by referring to the Steel Design Guide Series 14:Staggered Truss Framing Systems of American and Chinese relevant codes,one-third scaled specimen of five story composite staggered truss structure was designed by the software ETABS in terms of similar theory.The design considered the internal forces under the effects of wind load combinations,seismic load effect combinations and limit load effect combinations.In addition,the floor of the model has also been designed.And then Pushover analysis was carried out on the model to obtain basement shear force-displacement curve,the formation and development of the plastic hinge and the failure mode of the model,in terms of which the testing scheme was drawn up.The pseudo-static test was carried out on the model.Based on the test results,the P-Δhysteresis curve,the P-Δskeleton curve and the limit supporting capacity were found,also the ductility and performance of plastic deformation,the energy consumption ability,the strain distribution and failure mechanism were analyzed.The following conclusions would be suggested in terms of test results:The P-Δskeleton curve of composite staggered truss structure appeared steady and plump without obvious pinching;The bearing capacity of the composite staggered truss structures was high,but the ductility and plastic deformation ability were not very good;the first story is structural weak story;The columns in the composite staggered truss structure were mainly subjected to large moment along the weak axis with little moment along strong axis under transverse loading,and the chords subjected to both moment and axial force, the web member subjected to axial force;he failure mode of the composite staggered truss structure belonged to beam(truss) plastic hinge mechanism.