Numerical tool to study structural reinforcement of steel reinforced concrete (RC) structures under seismic loads using fiber reinforced polymers (FRP)

Abstract

Strengthening or retrofitting existing structures in order to increase their ductility and improve their seismic response has traditionally been accomplished using conventional materials and construction techniques. Composite materials of a polymeric matrix reinforced with long fibres (FRP) have emerged as an alternative to these methods.
To view the performance of these reinforcements when seismic loads are applied, this work studies the structural response of a frame joint when a horizontal load is applied to it. Under a seismic load, joints are one of the weakest parts of these structures. The response of a plain concrete frame joint is compared with the response obtained when it is reinforced using FRP. Different configurations of FRP reinforcements are considered to compare their behaviour.
The structural response of all structures considered is obtained with a numerical simulation. This is done using the finite element method. Composites are treated using the mixing theory, which obtains the composite behaviour by means of the composition of each component material properties. Each component is simulated with its own constitutive equation. The anisotropy usually found in composite
components is treated using a mapped space theory. The debounding effects found in composite materials are treated using the formulation developed by E. Car and S. Oller [Car, 2000].
The results obtained validate the use of FRP reinforcements to improve frames seismic response. The structure load capacity is increased in a 20% when lateral reinforcements are applied to the joint. This can avoid the structure to collapse in a seismic case. They results also show a good performance of the numerical tool developed.