Quantification study for roof truss subjected to near-fault ground motions

The effects of vertical seismic excitations have a considerable destructive potential for long-span structures, particularly for near-field earthquakes. A quantification analysis is carried out in this paper to describe the response of a 25-m long trapezoidal truss frame with a height of 9 m under Vertical Ground Motion (VGM) with the help of eight near-field seismic excitations. Linear analysis of earthquake load combinations, including VGMs, has been conducted. The VGMs are leading the design of the long-span roof truss rather than the wind load. The time history analysis is therefore performed for horizontal ground acceleration and horizontal plus vertical acceleration using SAP 2000. For this analysis, eight near-field earthquake ground motion records consisting of four with pulse and four without pulse from the PEER NGA database, consistent with the ATC-63 requirements, are selected. The response of the structure is observed in different parameters such as the axial force of the column, the vertical displacement of the ends of the roof truss and the edge of the truss, the axial load of the bottom truss, and the base moment. This work quantifies the effect of vertical seismic excitations on a long-span industrial trapezoidal truss and demonstrates the need for a time history study of the VGM component.