Title: Thermal Performance of Concrete Slabs Reinforced with Glass Fiber-Reinforced Polymer Bars

Author(s): Yail J. Kim and Jun Wang

Publication: Structural Journal

Volume: 119

Issue: 6

Appears on pages(s): 67-82

Keywords: fiber-reinforced polymer (FRP); modeling; slabs; temperature; thermal performance

DOI: 10.14359/51733141

Date: 11/1/2022

Abstract:
This paper presents the thermal performance of one-way slabs reinforced with glass fiber-reinforced polymer (GFRP) bars, including ordinary concrete, high-strength concrete (HSC), and ultra-high-performance concrete (UHPC). A state-of-the-art simulation technique, called agent-based modeling, is adopted to implement the differential equations of heat transfer in conjunction with ASTM E119 standard fire. Alongside the thermal absorptivity of the concrete materials, the slabs’ time-dependent responses are predicted during a fire rating of 3 hours with and without vermiculite-gypsum insulation. A parametric study is conducted to propose design recommendations. When the external temperature ascends, the conductivity and density of all concrete types increase, whereas their specific heat declines. The temperature profiles of the slab sections change over time and the mitigation of thermal gradients reduces the heat flux differentials near the slab surface. The addition of the insulation layers retards the propagation of thermal distress, which is particularly beneficial for the UHPC. Following the interface deterioration between the concrete and the reinforcement, the degraded modulus of GFRP influences the flexural capacity of the slabs. At a 3-hour fire rating, the remaining capacity of the slab without insulation varies from 34 to 46% of the intact capacity, while the capacity increases up to 75% for the insulated slab. Care should be exercised if either UHPC (180 MPa [26,100 psi]) or high-modulus GFRP (60 to 100 GPa [8700 psi to 14,500 ksi]) is used because premature GFRP rupture can take place before reaching the intended fire rating. Practice guidelines are suggested to accomplish the performance-based design.