Abstract
This study deals with the serviceability of reinforced concrete solid and perforated rafters with openings of different shapes and sizes based on an experimental study that includes 12 post-fire non-prismatic reinforced concrete beams (solid and perforated). Three groups were formed based on heating temperature (room temperature, 400 °C, and 700 °C), each group consisting of four rafters (solid, rafters with 6 and 8 trapezoidal openings, and rafter with eight circular openings) under static loading. A developed unified calculation technique for deflection and crack widths under static loading at the service stage has been provided, which comprises non-prismatic beams with or without opening exposed to flexure concentrated force. Two approaches were used to compute the deflection: The first attempt was conducted by using the moment of inertia for solid non-prismatic beam and reduced for those with openings by the ratio of residual rafter self-weight. The second was performed by using the moment of inertia of transformed cracked sections depending on the segmental rafter method. The crack width was determined using the ACI code's equation. The analytical and experimental results were evaluated and found to be in good agreement.
Highlights
Because concrete has a comparatively cheap material cost, a strong reputation for excellent fire resistance, and low maintenance requirements, RC rafters can be utilized as an alternate preferable choice to support broad area roofs of warehouses, industrial buildings, and aviation hangars
The " Residual Area Method " employed a further method. This approach yields a set of formulae for calculating the critical temperature in the steel profile. (Kodur and Agrawal, 2016) give a technique for determining the residual capacity of RC beams exposed to fire was presented
The numerical analysis predictions have a high agreement with the response parameters observed in experiments for assessing the residual capacity of RC beams subjected to fire. (Mansur, et al, 1992) proposed a rigorous method to calculate the deflection of beams with openings
Summary
Because concrete has a comparatively cheap material cost, a strong reputation for excellent fire resistance, and low maintenance requirements, RC rafters can be utilized as an alternate preferable choice to support broad area roofs of warehouses, industrial buildings, and aviation hangars. (Wickstrom, U., 1986) created one of the earliest models; this "extremely basic" model predicted the temperature profile within concrete using data already established from conventional fire curves This approach can only be used on buildings that have been subjected to temperatures within the normal timetemperature curve. (Mansur, et al, 1992) proposed a rigorous method to calculate the deflection of beams with openings In this methodology, the rafter is considered as a structural member with multiple segments that make up the solid parts and the sections crossed by the opening. F., 2015) investigated the performance of CFRP wrapping jackets used for retrofitting twelve square reinforced concrete (CR) column specimens damaged by exposure to fire flame, at different temperatures of 300, 500, and 700oC, except for two specimens that were not burned.
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