Seismic design for steel trussed arch to multi-support excitations

The behavior of steel trussed arch to multi-support excitations is studied. The spatial variation of ground motion is modeled by an empirical coherency loss function. Numerical results indicate that horizontal multi-support excitations have a quite large amplification effect on the seismic responses of the trussed arch. This amplification effect cannot be ignored in the seismic design of such structures. Vertical multi-support excitations reduce the seismic responses of the trussed arch. Therefore the assumption that vertical free-field ground motions are spatially uniform is available to assure the degree of seismic safety reliability of the trussed arch. An average response spectrum method is subsequently introduced to calculate the arch response to multi-support excitations. The advantage of the method is that the linear peak seismic response of the arch to multi-support excitations can be obtained as conveniently as the conventional response spectrum method does. The good agreement of results between the time-history method and the average response spectrum method shows the validity of the latter method.