Effect of thermal creep on the behavior of flush end-plate connection under transient conditions of fire

Abstract

The properties of steel material become dependent on the temperature and duration of heating during a fire event. Thermal creep strain is a time-dependent plastic deformation that becomes significant under constant load and high temperatures. The goal of this study is to understand the thermal creep effect on the behavior of a beam-column flush end-plate connection subjected to transient fire conditions. Finite element models were developed and validated against experimental work available in the literature. Parametric studies were conducted to study the overall response of the connection with and without the explicit consideration of thermal creep. The parameters included are heating/cooling rate, beam length, load ratio, plate thickness, bolt size, column axial compressive force, and creep effect in bolts. The thermal creep effect decreases the beam thermal induced compressive forces and simultaneously causes larger mid-span deflections at high heating temperatures. At slow heating rates, the effect of thermal creep can significantly reduce the compressive force at the end of heating while generating high tensile forces at the end of cooling. Neglecting the thermal creep in the analysis may cause inaccurate prediction of the tying forces and rotational demand of the connection.