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Integral abutment bridges have many advantages over bridges with expansion joints in terms of economy and maintenance costs. However, in the design of abutments of integral bridges temperature loads play a crucial role. In addition, seismic loads are readily transferred to the substructure and affect the design of these components significantly. Currently, the European and American bridge design codes consider these two load cases separately in their recommended design load combinations. In this paper, the importance and necessity of combining the thermal and seismic loads is investigated for integral bridges. A 2D finite element combined pile-soil-structure interactive model is used in this evaluation. Nonlinear behavior is assumed for near field soil behind the abutments. The soil around the piles is modeled by nonlinear springs based on p-y curves. The uniform temperature changes occurring at the time of some significant earthquakes around the world are gathered and applied simultaneously with the corresponding earthquake time history ground motions. By comparing the results of these analyses to prescribed AASHTO LRFD load combinations it is observed that pile forces and abutment stresses are affected by this new load combination. This effect is more severe for contraction mode which is caused by negative uniform temperature changes.

The occurred damages during the past significant earthquakes have proved that vertical seismic excitation has tremendous effect on bridges. Three-component earthquake excitations are preferred to resemble the earthquakes. In this article, a cable-stayed arch bridge, a new type of bridge with the hybrid system of half-through arch and stay-cables, was analyzed under a set of different earthquake excitations (more than 21 ground motion records). Both vertical and horizontal components of the ground motions were considered to act simultaneously at the bridge supports. By using different three-component earthquake excitations, the dynamic responses of the bridge, including the displacements and accelerations of the main parts of the bridge, were obtained. The effects of various parameters such as soil type, epicentral distance, spatial variation of the ground motions, and dimensional variation of the structure were investigated. The results of the numerical study indicate that the cable-stayed arch bridge subjected to both horizontal and vertical components of earthquakes are more vulnerable than those subjected to horizontal ground motion only.

The paper studies a pendulum isolator. This isolator has a spherical surface which is placed on the foundation and it has an arm which is connected to the column of the building as a hinge. When the height of the arm is less than the curvature radius of the spherical surface, and a small movement is applied on it, a restoring force will be applied to the isolator. In this paper the effect of horizontal and vertical component of seismic load was studied. The dynamic equation of motion was obtained for the pendulum isolator under horizontal and vertical accelerations of seismic loads. The equation was solved by step time integration method. The comparison of the results of horizontal component effect and the combined effect of horizontal and vertical components on the isolator showed that the vertical component effect increased the isolator horizontal displacement response and increased the isolator horizontal acceleration.Keywords base isolation · vibration control · pendulum isolator · earthquake vertical acceleration effect · combined horizontal and vertical components effects of earthquake