Title: Modeling Cyclic Response of CFRP Strengthened Fiber Anchored RC Frame Members to Failure

Author(s): Salman Alshamrani, Sama Mohammed Saleem, Hayder A. Rasheed, and Fahed H. Salahat

Publication: Symposium Paper

Volume: 360

Issue:

Appears on pages(s): 423-441

Keywords: Seismic strengthening; CFRP fiber anchors; Frame members; Hysteresis modeling; Backbone curve.

DOI: 10.14359/51740641

Date: 3/1/2024

Abstract:
There is a shortage of studies related to the effects of fiber anchorage on the behavior of strengthened frame members undergoing seismicity. This study models experimental data of four frame specimens having seismic code-compliant joints with CFRP-strengthened members secured with different fiber anchorage systems. Analytical formulation using a trilinear moment-curvature response is extended to accurately model the envelope curves of the vertical frame member by including the nonlinear interaction from the horizontal member, which presents a new solution. Furthermore, the experimental hysteresis data provides a basis to formulate an analytical model based on phenomenological observations to capture the cyclic load-drift curves. When modelling the drift-based hysteresis loops, each cycle is divided into three linear regions in the unloading and reloading paths, respectively. These are named push-bound, inflection range, and pull-bound regions. Curves correlating the ratio of unloading and reloading slopes of these regions to the initial backbone curve slope as a function of the drift ratio to yielding drift ratio are generated. These curves define the rules that the hysteresis loops behave according to. The hysteresis rules are calibrated against two different RC frame assemblies and used to predict the cyclic response of two other frame assemblies with similar features.