Research On Global Stability Of Staggered Truss High-rise Steel-timber Combined Structure

Unstable failure of structure always happens suddenly, the structure immediately crashesonce the buckling occurs. Unstable failure is more dangerous than strength failure confirmedby many practical engineering accidents. Stability analysis of structure is very important.Staggered truss high-rise steel-timber combined structure is a new green residence,it has thecharacteristics of small size of section, slender component, flexible plate element.Makingglobal stability analysis of this structure to explore its system of unstable failure andinfluencing factors of global stability, provide design basis.The thesis first makes structure design of staggered truss high-rise steel-timber combinedstructure according to the architectural scheme of a15-story residence in Nan Jing usingSAP2000,then analyses its mechanical behavior under basic composition and accidentalcombination. The results show that, under basic composition, internal force of chords,webmembers,framecolumns and joists is low, moment and shear in transverse plane have beenmainly concentrated in the truss layer, moment and shear of frame columns are low, and framecolumns mainly bear axial force.This structure makes full use of tensile propertiesand flexuralbehavior of steel,and compression resistance capability wood, two materials both exert theiradvantages.The results also show that, under accidental combination, staggered trusses areregarded as lateral resistant system,most horizontal shear turns into axial force of tilted bellypoles,columns mainly bear axial force,structural lateral displacement reduces greatly. Thisstructure shows good mechanical behavior and seismic capacity.Then, the thesis makes a whole stability analysis of this staggered truss high-risesteel-timber combined structure by ANSYS. Material nonlinearity and geometrical nonlinearityare considered simultaneously in this analysis. By proper calculation technology, the loaddisplacement curves and ultimate bearing load are obtained, which can show the safety storageand overload capacity. Moreover, according to the result of bi-nonlinear analysis results, plasticdevelopment of the important components is analyzed in detail. The results show that, staggeredtruss high-rise steel-timber combined structure has large ultimate bearing capacity and goodductility.Finally, the thesis analyses the main influence factors of the global stability of thisstructure. The factors considered mainly include as follow: structural materials, building heightto width ratio, section sizes of frame columns, lateral resistant system, storey height and so on.Results show that ultimate bearing capacity of pure steel structure is a little larger than steel-timber structure combined staggered truss system; The ultimate bearing capacity ofstructure decrease with the increase of building height to width ratio; Increasing the sectionsizes of frame columns has remarkable effect to improving ultimate bearing capacity ofstructure. The setting of longitudinal braced is not of any meaning to the structure, buttransverse brace can improve ultimate bearing capacity and control lateral displacement of thestructure. With the increase of storey height, lateral stiffness of structure decreases, ultimatebearing capacity reduces,and lateral displacement of structure increases. Building height towidth ratio, section size of frame columns and storey height should be controlled to suitablelevels to meet the requirement of safety and economy.