High-temperature creep of concrete

Abstract

Abstract Axisymmetric or spherical concrete structures designed with tensioned or non-tensioned steel reinforcement are used in civil engineering practice as reactor pressure vessels, containers for chemicals, water towers or reservoirs, submarine oil tanks, caissons, bunkers, air-raid shelters, silos, cupolas, lighthouses, industrial chimneys, television aerial masts and central pylons for suspended cooling towers. In the course of analysing such structures using finite element and finite difference computing techniques, the author investigated the behaviour of concrete at ambient, elevated and high temperatures, and subsequently studied its effects on the structures' strain history. Since stress analysis problems of continua are insoluble in closed form except for simple ideal geometries, the strain history is reproduced matrix-theoretically by defining sets of scalar thermal relaxation factors which act as multipliers of the coefficients of the structures' stiffness matrix as present in the global force-deformation equation.