Experimental and numerical investigation on post-fire seismic performance of light weight aggregate reinforced concrete beams

• Published in: Engineering structures 2022-10, Vol.268, p.114791, Article 114791
• Main Authors: Dabbaghi, F., Yang, T.Y., Tanhadoust, A., Emadi, S.B., Dehestani, M, Yousefpour, H.
• Format: Article
• Language: English
• Subjects: Ambient temperature; Compressive strength; Concrete aggregates; Cracking (fracturing); Cyclic loads; Deformation; Degradation; Earthquake damage; Earthquake loads; Elevated temperatures; Energy dissipation; Energy dissipation capacity; Exposure; Fire resistance; Heat resistance; High temperature; Lightweight aggregate concrete (LWAC); Lightweight concretes; Mathematical models; OpenSees; Post-fire response; Prisms; Reinforced concrete; Reversed cyclic loading; Seismic activity; Seismic response; Stiffness; Strength degradation; Stress-strain relationships; Weight reduction
• ISSN: 0141-0296; 1873-7323
• DOI: 10.1016/j.engstruct.2022.114791

•Lightweight and normal weight aggregate reinforced-concrete beams were subjected to ambient and elevated temperatures.•Lightweight aggregate beams demonstrated better seismic performance at high temperatures.•The dissipated energy varied by the concrete type and the heat exposure level.•RC beams incorporating LECA can safely be implemented in structures subjected to seismic loads.•The finite element analysis can accurately simulate the seismic behavior of RC beams after exposure to high temperatures. The stringent demand for designing fire-resistant structures in recent years has triggered a good deal of effort into theoretical and experimental studies. Structures may be exposed to seismic loading after a fire in the course of their lifetime, resulting in the reduction of their integrity. This study examines the seismic performance of damaged light weight aggregate reinforced concrete beams by exposure them to elevated temperatures. Accordingly, a set of 8 light weight and normal weight concrete prisms were cast and tested under quasi-static reversed cyclic loading after exposure to temperatures of 25, 250, 500 and 750 °C. The stress-strain relationship, residual deformations, strength and stiffness degradation, energy dissipation capacity and cracking pattern of light weight beams were compared to those of the normal weight counterparts. The experimental results revealed that the light weight beams, although with lower compressive strength at ambient temperatures, show better seismic performance when exposed to elevated temperatures as compared to their normal weight companions. On this account, the residual deformations of the entire set of beams decreased with increasing the thermal exposure level. However, this was less pronounced in the case of lightweight prisms. In addition, the energy dissipation capacity of normal weight prisms was higher than that of the lightweight beam specimens at ambient temperature. Nonetheless, the dissipated energy in lightweight concrete overtook that of normal weight concrete as the temperature was increased. Moreover, the beams under investigation were numerically modeled in OpenSees through fiber section models in order to verify the obtained experimental results. The fire effect was applied in the compressive strength reduction of the beam specimens based on experimental results, such that each heat-exposure level relatively decreased the compressive strength of prisms. The results confirmed that the numerical respon