Analytical studies were conducted on force transfer mechanism of retrofitted anchorage system in structural concrete by Strut-and-Tie modeling (STM). Post Installation of Headed anchorage (PIHA) as supplementary system introduced for implicit strengthening of anchorage system. The boundaries of STM are considered under direct tension pull-out test. Five different configurations of conventional reinforcement anchorage in concrete with straight bar, 90-degree bend, 180-degree hook, single head and double head bars are retrofitted by using PIHA technique. The mechanics of force transfer in anchorage system was analyzed by STM and validated the results by experimental program. The study parameters considered are (i) location of nodal zone, (ii) strut angle, (iii) size of strut (concrete) contributed during failure. The study variables are (i) configuration of anchorage system (ii) characteristic node formation and (iii) presence of supplementary reinforcement. The result shows good agreement with experimental findings against failure mode, stress pattern, and location of critical zone in conventional and retrofitted anchorage system. Use of this study may further extended to assess theoretical evaluation of failure mode, formation of critical section and stressed regions of discrete RC elements such as corbel projection, bracket connections and beam-column joints.

The present paper is concerned with the seismic risk assessment of buildings in the Kingdom of Saudi Arabia. A critical review of the existing literature is presented to identify the shortcomings of extant studies. None of the extant studies considered nonlinear action of the beam-column joint (BCJ) but rather they dealt with BCJ as a rigid element for simplicity and the only plastic hinging has been considered in beams and/or columns. Hence the main focus of this paper is to demonstrate the significant effects of the nonlinear action of BCJ in the pushover analysis and in turn the inadequacy of all previous studies which overlooked such effect. In this study, nonlinear static pushover analysis is performed on two-dimensional RC frames of existing buildings in Jeddah city, with and without using macro node elements and pushover curves are compared. The beam-column joint modelling approach adopted in this study is through macro node element which accounts for failure due to shear collapse of the joint, concrete crushing, flexural and/or shear plastic damage of the beams or columns connected and bond-slip failure. The results clearly indicate that the RC frame in which the beam-column joints were modeled using a macro node element, tends to have lesser base shear values and higher displacement capacity when compared to the RC frame modeled without using the macro node. Furthermore, the status of plastic hinges developed in building frames modeled without using macro node element was found to be within the Immediate occupancy (IO) performance level, but this hinge status drastically changed to Collapse prevention (CP) performance level when BCJ was modeled using macro node. Hence, the results highlight that the nonlinear action of beam-column joint has a significant effect on the nonlinear response of a structure.