PSI - Issue 70

Alok Kumar et al. / Procedia Structural Integrity 70 (2025) 145–152

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1. Introduction Reinforced concrete (RC) structures are commonly used in construction for their strength, durability, and flexibility. However, in seismic areas, RC structures are to be damaged or collapse as a result of intense earthquakes. especially when constructed under old codes or with insufficient ductility and energy dissipation capacity. Enhancing the seismic performance of the buildings using the retrofitting of the existing structures for earthquake resistance. FRP composite materials have proven to be a successful substitute or addition to conventional steel reinforcement in concrete structures. FRPs are hybrid materials that contain high-strength fibre carbon, glass, or aramid spread out in a polymer matrix. The pushover method of analysis can be used fornewbuildingsor existing buildings toevaluatein termsoflateral force or seismic force and deformation demand. Non-linear static procedure (NSP) canbe applied to structure in many methods which are the Capacity spectrum method, Displacement coefficient method and Modal pushover analysis Seismic performance of a structure can be checked in terms of pushover curve, plastic hinge formation, etc. The maximum base shear capacity ofthestructure can beknownfrom base shearvsroof displacement curve. Sherif M. S. Osman et al. (2023) When the axial load ratio (AR) increased from 10% to 40%, the elastic deformation increased by 36.8%, along with a reduced inelastic material response of 37.5%. With an increase in FRP reinforcement ratio (RF) from 0.54% to 1.56%, the lateral forces at equivalent yield and maximum base shear increased by 25.5% and 28.8%, respectively. Bo Tong Zheng et al. (2024 ) Under reversed cyclic loading up to a 7% drift level, the assembly reached its peak load at a 4% drift, with the residual load capacity at 5% drift being approximately 50%. Analysis of the hysteresis curves revealed that the specimen showed minimal pinching during the 7% drift level. Overall, the assembly demonstrated the expected seismic performance.

Nomenclature CFRP Carbon fibre-reinforced polymer DBE=Design basic earthquake MCE=maximum considered earthquake SMRF=Special moment resisting frame

2. Building Description The building investigated in this study is a G+5 reinforced concrete (RC) multi-story frame building located in a zone of high seismicity, Earthquake Zone V. The rectangular plan layout is 20 meters in length and 20 meters in width. It stands 21 meters in height, with a uniform floor-to-floor level of 3.5 meters for each of its floors. The configuration is four bays in the x-direction and four bays in the y-direction, each bay being at a spacing of 5 meters. The foundation system has fixed support. The building is assumed to be founded on medium-type soil, Type II. For dynamic analysis, a damping ratio of 5% is used, which is typical for RC structures. It is assumed that the importance factor (I), which denotes a typical occupancy category, is 1.5. As with a Special Moment Resisting Frame (SMRF) system, a response reduction factor (R) of 5 is employed to account for the structure's ductility performance under seismic loads. The building's structural components are made of reinforced concrete whose normal compressive strength (Fck) is 25 MPa. The reinforcement material used across the structure is high-yield strength steel with a yield strength (Fy) of 500 MPa. Beams are 250 mm wide and 350 mm deep, and columns are spaced at sizes of 400 mm by 400 mm to provide adequate strength and stiffness to withstand vertical and lateral loads. The floor system consists of a 125 mm thick RC slab, which is adequate in load-carrying capacity and structural stability. Masonry infill walls are taken to be constructed of brickwork with a unit weight of 20 kN/m³, adding to the total weight of the structure and affecting its seismic response. The choice of these materials and cross-sectional sizes is in accordance with normal design practice and aimed at providing safety and serviceability under anticipated conditions of loading.