Papers by Keyword: R/C Frame

Abstract: The seismic fragility of R/C frames was redefined as the conditional failure probability of the structure with regard to the ground motion index and structural service age in this paper. An analytical method was proposed to disclose the seismic fragility variation of reinforced concrete frames with respect to the service age. Considering the variation of nonlinear mechanical characteristics of un-carbonated concrete within the service life, the seismic fragility variation of frames was analyzed using the inter-story drift ratio in the weak storey. For the defined damage levels of frames, each seismic fragility curve variation reflects the failure probability change tendency within the service life. A R/C frame was modeled to illustrate the variation of the seismic fragility within the service life.

Abstract: This study investigates an innovative method based on low yield steel plate shear walls for seismic retrofitting of existing reinforced concrete (R/C) structures. A simplified numerical model of steel shear panels is developed for global analyses of multi-story R/C frames. The seismic performance of a non-ductile five-story R/C frame retrofitted with steel plate shear walls is evaluated in terms of drift control and energy dissipation capacity using nonlinear dynamic analyses. The results obtained by the application of two different story-wise distributions of steel plates are compared. In case of retrofitted frames a considerable decrease of the maximum top displacements is registered and the energy dissipated by the primary structural elements is significantly reduced for severe seismic actions. The energy dissipation concentrates in the steel panels, reducing the plastic demand on the structural members, along with the potential for structural damage. The different story-wise distributions of the steel panels change the damage distribution throughout the frame. The uniform arrangement of the steel panel thickness along the height of the frame causes a concentration of damage in the columns of the first story. In case of steel panel distribution proportional to story shear, the energy dissipation results more uniform over the height of the frame and a significant decrease of damage is registered for the columns of all the storeys.

Abstract: This paper proposes a reliable and computationally efficient finite-element model (Partial Fiber Model) for the nonlinear analysis of reinforced concrete (R/C) frames under static and cyclic loading conditions that induce multiaxial bending and axial forces. The beam-column member is composed of three parts: middle elastic and two plastic regions at the two ends of beam. The plastic regions are discretized into longitudinal steel reinforcement and concrete fiber elements. The nonlinear behaviors of the elements are derived from the nonlinear stress-strain relations of the steel and concrete fibers. The global stiffness matrix of beam-column can be deduced from those of mentioned three parts. Numerical examples are calculated to prove the accuracy and efficiency of the model. The results of nonlinear analysis show the validity of the model to describe the nonlinear response of frame subjected to static and cyclic loadings.