The stability of precast concrete skeletal structures

Precast concrete forms a significant proportion of buildings in Europe, particularly in Northern Europe, Scandinavia and the Baltic countries. Yet the investment in research in precast concrete is much less than in structural steelwork and cast-in-place concrete, where construction practice is much more familiar. This paper presents an overview of the current research climate in Europe, together with details of work carried out in three European countries on structural stability. The design and analysis of precast skeletal structures is greatly influenced by the behavior of beam-to-column connections, where patented designs have led to a wide range of types with differing structural qualities. Full-scale experimental tests have been carried out to determine the influence of connection behavior on stability, both in the in-plane (bending) and out-of-plane (torsion) modes of sway. This paper shows how small quantities of reinforced cast-in-place infill concrete provide composite action between the precast elements to enhance strength, stiffness and ductility, leading to a semi-rigid behavior. Combined with a parametric column effective length study, test data are used to propose a method for the analysis of semi-rigid frames where column effective lengths are greatly reduced and second order (deflection induced) bending moments in the column may be distributed via the connectors to the beams, leading to significant economies.