M.A thesis at the college of engineering addresses the finite element method of concrete ceilings
A discussion of a master thesis took place in the department of civil engineering at the college of engineering, university of Baghdad, submitted by the student “Enas Mohamed Mahmoud” entitled “A comparison between the equivalent way (SDOF) and the finite element method of concrete ceilings exposed to blast (FEM)”. The search summarizes a comparison between two methods for nonlinear dynamic analysis to evaluate the conduct of reinforced concrete slabs exposed to blast. The researcher stated that it is possible to speculate the pressure resulting from blast by the curves existed in the U.S. blog about the “equivalent” method by finding the values of shift factors that transforms the “slab” to the “equivalent” system. The validity of results was evaluated and compared with the findings resulted from “the finite element method” and show that this method is more accurate in this analysis. In order to complete the nonlinear dynamic analysis with the “equivalent” method, the researcher found the function of resistance – precipitation at first, which has been found practically and theoretically by the use of non-linear static analysis for the slabs to find a relationship between resistance and precipitation. The researcher used computer for analyzing concrete blocks with eight nodes because this element has the ability to represent cracking and crushing. The variables taken into consideration by the researcher were as follows: proportion of rebar, mechanical properties of concrete and iron, the coefficient of blast, the thickness of the slab and the impact of types of backing. The results of the study showed that the finite element method gave lower values for static precipitation when compared with the results of the practical tests (8% -21%), while the finite element method gave higher values when calculating the static failure (2% -7%). When comparing results of these two methods, it was clear that the results of the finite element method gave higher results for dynamic precipitation (9% -22%) and that the impact of the above variables on the response of the concrete ceiling was similar (increase or decrease) in both methods, a decrease in the value of the absorbed energy (85%), an increase in the proportion of rebar at about 100% (0.005 to 0.01) that leads to a decrease in ductility and transitory precipitation (40% and 38%) respectively at the “scaled distance” coefficient (1.3 m / kg 1/3). The thesis was under the supervision of prof. Dr. Thamer Khudair Mahmoud and the discussion committee consisted of assistant professor Dr. Abbas Abdul Majeed Allawi as chairman and the membership of assistant professor Dr. Laith Khaled al-Hadithi and assistant professor Dr. Amir Farouk Ezzat.