Comparison of joint schemes between V-shaped steel tower and concrete base for cable-stayed bridge
A pedestrian bridge over river was designed as a cable-stayed bridge with special-shaped steel tower,in which two steel columns with box section meet just above concrete base to become asymmetric V junction.The axis of steel column was not perpendicular to the junction-concrete interface,and base size was strictly limited by the requirements of flood passage.These bring great challenge to the structural design of steel-concrete joint.On the basis of equivalent cost,three different kinds of joint schemes were preliminarily drawn up,that were the pressure type,the shear type and the combined type.The corresponding finite element model was established by using ABAQUS software.The combination with the maximum absolute value of in-plane and out-plane bending moments in the reaction force at the support of the tower bottom is selected for finite element analyses.The results were compared both among three schemes and to the provisions in the relevant codes.It shows that the combined pressure-shear joint can greatly reduce the stresses at the root of the steel column,the base and the anchor box,and reasonably meet the code requirements.In terms of the maximum displacement and stress variation amplitude near the column bottom,the largest values occurred in the shear type and the smallest in the combined type.In the combined scheme,the thickness of bearing plate is reduced by 1/3 compared with that of pressure type.The maximum Mises stress is increased but do not exceed the limit.So the material utilization rate is improved.The maximum principal tensile stress of the concrete base is far beyond the limit of the code in the pressure scheme,especially in the shear scheme,which cannot meet the requirements of cracking resistance.The maximum Mises stress at steel plate of the anchor box in the shear scheme also exceeds the standard limit by 22%,and it is at the same position as the maximum values of its vertical compressive stress and the principal tensile stress of concrete.The shear scheme is not applicable because the vertical plates on the side of the anchor box is not far enough to each other and unfavorable structural features leads to great angle between the rectangular plates and the column wall.The combined scheme is worthy of priority regardless of stress or deformation control.The research results can serve the project,and also have reference value for similar projects.
steel tower cable-stayed bridgesteel-concrete jointstructural connectionjoint schemefinite element analysis
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