Earthquake Response Analyses Of Plane Frame Structures Under Wave Passage Excitation

The seismic safety of frame structure is very important to the public life and property safety. the seismic analysis and design is taken seriously by countries in the world. Ultimately estimating the seismic responses of the frame structure is the precondition of seismic design and it is very important to ensure the safety of structures.To study whether wave passage effect should be considered in the seismic responses of frame structures or not, four plane frame structures are adopted. The first is a three-span, three-story reinforced concrete structure, the second is a three-span, six-story steel-concrete composite beam structure, the third is a three-span, six-storey reinforced concrete plane frame structure and the fourth is a two-span, ten-storey steel-concrete composite beam plane frame structure.The sites in accordance with the wave velocity of PEER database of the United States Geological Survey and code for seismic design of buildings is divided into four categories. In accordance with the requirements for seismic design of buildings on the earthquake fortification intensity of7degree, peak accelerations of the horizontal and vertical seismic waves adjust to0.1g and0.065g respectively.Based on the equations of motion for a structure subjected to multiple support excitations and Wilson-θ method, the earthquake responses of four plane frame structures to wave passage excitations and uniform excitations are computed by programming the FORTRAN language respectively for each of four sites’seismic waves. The results of the time-history curves of column shear forces and beam-end bending moments, the maximum column shear forces, the maximum beam-end bending moments and the displacement deformations of different moments of frame structure obtained from the wave passage excitations are compared with those of the uniform excitations.The numerical results showed that, for the three-span, three-story reinforced concrete plane frame structure, wave passage effects caused the shear force of the bottom-side column facing the seismic wave to increase remarkably for the plane frame structures being at site class Ⅲ. The increasing percentage is35%. At site class III. wave passage excitation increased significantly the beam-end bending moment of bottom beam facing the seismic wave compared with the result of uniform excitation. The increasing percentage is19%. For the three-span, six-story steel-concrete composite beam plane frame structure, wave passage effects caused the shear force of the bottom-side column facing the seismic wave to increase notably for the plane frame structures being at site class III. The increasing percentage is34%. At site class III. wave passage excitation increased remarkably the beam-end bending moment of bottom beam facing the seismic wave compared with the result of uniform excitation. The increasing percentage is21%. For the three-span, six-story reinforced concrete plane frame structure, wave passage effects caused the shear force of the bottom column facing the seismic wave to increase remarkably at site class IV. The increasing percentage is79%. At site class Ⅲ, wave passage excitation increased notably the beam-end bending moment of the first-storey beam facing the seismic wave. The increasing percentage is29%. For the two-span, ten-storey steel-concrete composite beam plane frame structure, wave passage effects caused the shear force of the bottom column facing the seismic wave to increase remarkably at site class IV. The increasing percentage is252%. Especially at site class III, wave passage excitation increased notably the beam-end bending moment of the first-storey beam facing the seismic wave. The increasing percentage is37%.It demonstrated that, for the first-storey column and beam facing the seismic wave in the plane frame structure, wave passage effect caused column shear force and beam-end bending moment to increase remarkably and the wave passage effects should not be overlooked in the earthquake response analyses even for frame structure.