Title: Out-of-Plane Behavior and Stability of Five Planar Reinforced Concrete Bearing Wall Specimens under Fire

Author(s): Kevin A. Mueller and Yahya C. Kurama

Publication: Structural Journal

Volume: 112

Issue: 6

Appears on pages(s): 701-712

Keywords: gas fire furnace; high-strength concrete; out-of-plane buckling failure; reinforced concrete bearing walls; structural fire engineering

DOI: 10.14359/51687908

Date: 11/1/2015

Abstract:
This paper describes a full-scale experimental investigation on the out-of-plane thermomechanical behavior of five planar reinforced concrete (RC) bearing wall specimens under fire. The wall specimens were heated on one surface over half of the wall height through the ASTM E119 standard fire time-temperature curve, while simultaneously being subjected to a constant axial load at the top. The walls were fixed at the base and free to displace vertically and rotate at the top. In the out-of-plane lateral direction, the top of three specimens was restrained (representing a rigid floor slab), the top of one specimen was free (representing a compromised or nonexistent floor slab), and the top of one specimen was subjected to a step-wise increasing lateral load (to investigate the change in wall lateral stiffness during the fire). The test results show that, depending on the wall thickness, reinforcement, and loading, the combined axial-lateral strength and stability of RC bearing walls can be severely compromised by the development of eccentric conditions from the unsymmetrical deterioration of the concrete and reinforcing steel over the wall thickness. Significant axial-flexural and diagonal cracking from large thermal gradients over the wall thickness and height can also contribute to the deterioration of the wall. Out-of-plane shear and buckling failures were observed at fire durations much shorter than the resistance rating per Section 2.1 of ACI 216.1 for the fire resistance of concrete structures.