Seismic design of R/C piers of hollow circular cross sections

Paper in proceeding, 2013

Hollow circular cross sections are widely used in piers. However, it is known that they are especially sensitive against inelastic deformation and therefore their use should be avoided, when it comes to ductile seismic resistant bridge systems. Consequently, it is important that such sections are to be utilized in non-ductile systems, namely in cases where the numerical value of the behaviour factor q lies between 1 and 1.5. In such cases, there is a certain level of impact upon their design. As far as the flexural design of hollow circular R/C cross sections is concerned, it should be based on the yield strength of the tension zone rather than the maximum bending strength. The problem of the transverse spiral reinforcements and the question whether the active presence of an inner spiral is actually needed (given that the inner spiral can jeopardize the integrity of a structural element, when there are no additional restraint measures), are also affiliated with the flexural design. On the other hand, the shear design of such sections can be even more difficult, when it comes to both the determination of the transverse spiral reinforcements and the maximum shear strength, which is influenced by the curved struts of the virtual network mechanism. In this paper, a thorough analysis of the design of hollow circular R/C cross sections is attempted, given that the compliance criterion is the value of the flexural yield strength, rather than the maximum failure strength.