Structural Engineering

By: Irene Calaizis

In May 2008 Prof. Mark Bradford and Dr. Ehab Hamed presented some of the outcomes of the ARC Discovery project which deals with the “Long-Term Nonlinear Behaviour of Shallow Concrete Domes” (awarded to Profs. MA.Bradford and RI.Gilbert) at the 6th International Conference on Computation of Shell and Spatial Structures (IASS-IACM 2008) that was held on the campus of Cornell University in Ithaca, New York State.

The proceedings focused on “Spanning Nano to Mega”, and on computations for any long-span, lightweight, fabric, or thin-walled structures. Over 200 worldwide scientists and engineers attended the conference. 

Prof. Mark Bradford presented the paper “A local failure mode for shallow spherical concrete domes subjected to uniform radial pressure” (by Z-T Chang, MA Bradford and RI Gilbert). The paper presents a new simplified design methodology for predicting local failures in shallow concrete domes. Such local failures, which have been observed in some experimental studies that appear in the literature and in the experimental study undertaken at the UNSW Heavy Structures Research Laboratory at Randwick, dominate the total failure of concrete domes. The proposed simplified model that was validated through comparison with the available experimental data, is based on the yield line method and explains some of the critical aspects that characterize the failure of shallow concrete domes.

Dr. Ehab Hamed presented the paper “Effects of boundary conditions on the non-linear long-term behaviour of spherical shallow concrete domes” (by E Hamed, MA Bradford, and RI Gilbert). The paper presents a breakthrough new theoretical approach for the nonlinear long-term analysis of concrete domes, which is based on variational principles, incremental nonlinear constitutive relations of the concrete material, and on a step-by-step superposition solution technique. The findings of the paper shed light on the long-term behaviour of shallow concrete domes, and especially on the effect of uncertainty regarding the real boundary conditions of the structure.

Currently Dr. Hamed together with Prof. M.Bradford are developing a general theoretical model that will account for imperfections, cracking, and material nonlinearity effects in the long-term analysis of shallow concrete domes. Concurrently, Dr. Z-T Chang together with Prof. M.Bradford and Prof. I.Gilbert are undertaking the long-term tests.