Nonlinear Response Analysis Of Single Steel Tubular Arch Truss Under Multi-Support And Multi-Dimensional Earthquake Excitations

At present, the steel tubular arch truss is one kind of long-span spatial structures which is widely applied in the public place of crowd crowded or the disposition critical facility. As known, the effect of traveling wave and multi-dimensional excitation are noticeable on seismic response of the long-span arch truss. Therefore, considering the effect of traveling wave and multi-dimensional, study on the earthquake resistance performance of arch truss under the multi-support and multi-dimensional earthquake excitation has the project practical value. Revolving this topic, this article takes an 84m-span's steel tubular arch truss as object, considers the self-weight of structure, the geometry nonlinear and material nonlinear, uses the large mass method model, analyses the nonlinear response with ANSYS finite element procedure. The main research work covers the following aspects:(1) Comparisons are made between single-dimensional and multi-dimensional response,simple-support and multi-support response. The results indicate that: Under multi-dimensional and multi-support earthquake excitation, axial force of middle-cross upper bar and bottom bar and 1/8 cross bottom bar as the velocity decreases significantly increase its value, axial force of upper and bottom bar more evenly than multi-dimensional and simple support earthquake excitation, the plastic bottom bar increased significantly; Multi-support earthquake excitation, the Level -X component to the role of characteristics node's displacement is big than the vertical displacement response component alone, the Z direction displacement of middle-cross and the response distinction between multi-dimensional earthquake and Level-X component increased obvious along with the reduce of wave velocity; Multi-support earthquake excitation, the Level -X component to the role of critical bar's axial force is big than the vertical displacement response component alone, and the response distinction between multi-dimensional earthquake and Level-X component reduced gradually along with the reduce of wave velocity; the max value of critical bar's axial force corresponding to different velocity under multi-dimensional earthquake. Obviously, analyzing the seismic response of this structure must to consider the participation of the vertical earthquake component and the influence of traveling wave effect, according to multi-support and multi-dimensional seismic motions excitation.(2) Selected the El Centro wave, NingHe wave and the artificial wave, and analyzed the dynamic response of structure under the different earthquake wave action. The result indicated: This structure's overall displacement and axial force biggest under the NingHe wave action, the artificial wave take second place, the El Centro wave is smallest.(3) Selected three different kind of rise-to-span of this structure, analyzed the response of multi-dimensional earthquake with simple excitation and multi-support excitation as the wave velocity 100m/s. The result indicated: Overall response of structural characteristics node's displacement and axial force of bar, multi-support and multi-dimensional earthquake excitation is greater than simple support earthquake excitation; the max value of upper bar's axial force increased along with the reduce of wave velocity, but the change of bottom was little; the displacement of characteristic node and the development degree of bottom plastic bar reduced along with the reduce of rise-to-span under simple support and multi-dimensional excitation ; the X-direction displacement of characteristic node was still reduced with the reduce of rise-to-span ,but the Z-direction displacement of characteristic node and the development degree of bottom plastic bar increased along with the reduce of rise-to-span under simple support and multi-dimensional earthquake excitation. The Z-direction displacement of characteristic node and the development degree of bottom plastic bar can have the poles apart change rule along with the change of rise-to-span under these two different methods. Obviously, accurately analyze the rule of structural response allowed change of rise-to-span under the seismic action must according to multi-support excitations.