Flexural performance of non-loadbearing blast-resistant precast concrete cladding panels with discrete connections

Abstract

Boundary conditions of non-loadbearing precast concrete cladding panels differ from monolithic cast-in-place walls by relying on discrete connections for attachment to the main structural system, typically at the floor diaphragms. When the panels are designed to resist far-field blast loading, discrete connections at the diaphragms are commonly idealized as horizontal lines of continuous support, with cladding panels are analyzed assuming vertical (primary) one-way flexural behavior. Two-way or horizontal (transverse) one-way flexural response can realistically occur with variations in reinforcement layout or connection spacing; however, these modes of flexural response are typically neglected in conventional design approaches but could severely limit a panel's flexural ductility and capacity. In this paper, a validated nonlinear finite element model is used to conduct a comprehensive parametric study of the flexural responses of solid non-loadbearing precast concrete façade panels with discrete connections subjected to uniform lateral (normal) pressure. Sensitivity of ultimate flexural capacity based on discrete boundary conditions is examined for different ratios of primary to transverse reinforcement as well as different vertical-to-horizontal span aspect ratios. Models with discrete connections were able to achieve a vertical mechanism by either decreasing the ratio of vertical-to-horizontal flexural capacity and/or increasing the number of lateral connections (thereby reducing the horizontal span between connections). For panels with vertical-to-horizontal span aspect ratios near 1.0, a vertical-to-horizontal flexural capacity ratio of 0.5 was needed to develop the vertical plastic mechanism. For panels with vertical-to-horizontal span aspect ratios greater than 1.5, a vertical-to-horizontal flexural capacity ratio of 1.0 was needed to develop the vertical plastic mechanism.