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Civil-Comp Proceedings
ISSN 1759-3433
CCP: 79
Edited by: B.H.V. Topping and C.A. Mota Soares
Paper 260

Semiloof Element Formulation: New Computer Coding and Applications

J. Noorzaei, M.S. Jaafar, W.A. Thanoon and J.N. Wong

Department of Civil Engineering, Faculty of Engineering, Universiti Putra Malaysia, Selangor, Malaysia

Full Bibliographic Reference for this paper
J. Noorzaei, M.S. Jaafar, W.A. Thanoon, J.N. Wong, "Semiloof Element Formulation: New Computer Coding and Applications", in B.H.V. Topping, C.A. Mota Soares, (Editors), "Proceedings of the Seventh International Conference on Computational Structures Technology", Civil-Comp Press, Stirlingshire, UK, Paper 260, 2004. doi:10.4203/ccp.79.260
Keywords: semiloof shell, semiloof beam, fortran, flooring, roof, idealization.

Shell problems are difficult especially when the shell is very thin and in addition, one of the principal curvatures is positive and the other negative or zero. It is particularly suitable to modal complex civil engineering structures such as cooling tower including staging columns and ring beams, flooring or roofing systems.

Finite element analysis of thin shells received considerable attention during recent year and a number of finite elements for thin shell analyses have been derived. Among these, the semi-loof element occupies a special place owing to its generality, type of formulation and performance. At present the semi-loof element is probably one of the most efficient element available for the solution of thin shells of arbitrary geometry. The present study deals with development of a three dimensional semi-loof finite element software based on programming code presented by Martin and Oliveira [1,2]. The finite element formulation for semi-loof beam, plate and shell are presented by Iron and Ahmad [3], Owen and Martin [4], Martin and Oliveira [1,2] but with limited computer coding and application.

At initial stage of this study, the subroutines SLSTIF and BMSTIF published by earlier investigator are implemented under Fortran environment. These subroutines are concerned with generation of stiffness, mass and load matrices. Then pre- processor (Noorzaei [5]), solution routine (modified frontal technique) developed by Godbole et al. [6] and post-processor (Noorzaei [5]) are added under a master main. The three dimensional finite element software package is compatible with Fortran 90 power station computer. The program is multi-element in nature and can deal with concentrated, pressure and gravity loadings (i.e only static loading). Besides that, there is compatibility between the shell element and beam element. At present the software application is limited to linear analysis.

The calibration of this upgraded semi-loof computer code has been well established by analyzing some benchmark problems, for which the analytical solutions are available in the literature. The application of the software is shown extensively in the analysis of complex structures such as scordis shell roof, flooring system and cooling tower including the ring beams. An attempt has been also made to compare the results obtained via present software with that of commercial finite element packages such as STRAP [7].

Based on these formulations, a three dimensional finite element software package has been coded and verified. The complex structures as flooring, roofing and cooling tower have been analyzed by using semi-loof shell elements which show the application of this element in predicting perfect behavior of theses structures. Also semi-loof beam element for representing the straight curved and its combination with semi-loof shell element has been clearly worked out. It is proven that the software can applied to any complex civil engineering structures.

R.A.F. Martin, C.A.M. Oliveira, "Semi-loof shell, plate and beam elements - new computer versions: Part 1", Engineering Computations, 5, 15-25, 1988a. doi:10.1108/eb023716
R.A.F. Martin, C.A.M. Oliveira, "Semi-loof shell, plate and beam elements - new computer versions: Part 2. Elements programming", Engineering Computations, 5, 26-38, 1988b. doi:10.1108/eb023717
B.M. Irons, S. Ahmad, "Technique of Finite Element", Ellis Horwood Ltd., Chichester, England, 1980.
D.R.J. Owen, R.A.F. Martins, "Elasto plastic and geometrically nonlinear thin shell analysis by semiloof element", International Journal of Computers and Structures, 13, 505-513, 1981 . doi:10.1016/0045-7949(81)90045-6
J. Noorzaei, "Non-linear soil structure interaction in framed structure", Ph.D thesis Department of Civil Engineering I.I.T, Roorkee India, 1991.
P.N. Godbole, M.N. Viladkar, J. Noorzaei, "A Modified Frontal Solver with Multi-Element and Variable Degrees of Freedom Features", International Journal of Computer and Structures, 39 (5), 525-534, 1991. doi:10.1016/0045-7949(91)90061-P
Structural Analysis Programs (STRAP) user manual, version 8.0, 1999.

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