Usmani, Asif

Bisby, Luke

Jiang, Jian

2013-09-11T08:41:13Z

2013-09-11T08:41:13Z

2013-07-01

The behaviour of heated structures is strongly governed by thermal induced deformation and degradation of material properties. This thesis presents an augmentation of the software framework OpenSees to enable thermomechanical analysis of structures. The developments contributed to OpenSees are tested by series of benchmark cases and experimental results. OpenSees is an object-oriented, open source software framework developed at UC Berekeley for providing an advanced computational tool to simulate non-linear response of structural frames to earthquakes. OpenSees was chosen to be extended to enable the modelling of structures in fire. The development of this capability involved creating new thermal load classes to define the temperature distribution in structural members and modifying existing material classes to include temperature dependent properties according to Eurocodes. New functions were also added into the existing corotational beam/column element (2D and 3D) to apply temperature related loads. A new geometrically nonlinear shell element was created (based on the existing linear MITC4 shell element in OpenSees) using total Lagrangian formulation. Appropriate thermal load, material and section classes were also developed for enabling thermomechanical analysis using the nonlinear shell element. A number of benchmark tests were carried out to verify the performance of the new developments implemented in OpenSees. The benchmark tests involved subjecting beams and plates to a range of through depth temperature gradients with OpenSees results compared against closed form solutions. Further verification was also carried out by comparing OpenSees results with ABAQUS results. The extended OpenSees framework was also used to model experiments such as two plane steel frames at elevated temperatures, the Cardington Restrained Beam Test and the Cardington Corner Test and an earthquake damaged reinforced concrete (RC) frame subjected to a subsequent fire. The existing DruckerPrager material class in OpenSees was used to the model concrete in the composite floor in the Cardington tests and in the RC frame. The pinching material available in OpenSees was used to model the beams and columns in the RC frame to consider the cyclic degradation of strength and stiffness during the increasing cyclic displacements imposed on the RC frame before the fire. In all cases the results from OpenSees show good agreement with test data.

http://hdl.handle.net/1842/7749

en

The University of Edinburgh

Asif Usmani, Jian Zhang, Jian Jiang, Yaqiang Jiang and Ian May. Using OpenSees for structures in fire, 3(1): 57-70, 2012.

Mariyana A. Ab-Kadir, Jian Zhang, Jian Jiang, Asif S. Usmani, Martin Gillie, Umesh K. Sharma and Pradeep Bhargava. Modelling of an earthquake damaged RC frame subjected to fire. Proceedings of 7th International Conference on Structures in Fire, Zurich, 479-489, 2012.

J. Jiang, A.S. Usmani. Thermo-mechanical analysis of steel frame structures using OpenSees. Proceedings of the 19th UK Conference of the Association for Computational Mechanics in Engineering, Edinburgh, 209-212, 2011.

J. Jiang, A.S. Usmani, J. Zhang, P. Kotsovinos. Numerical analysis of structures in fire using OpenSees. Proceedings of International Conference on Applications of Structural Fire Engineering, Prague, 319-323, 2011.

A.S. Usmani, J. Zhang, J. Jiang, Y.Q. Jiang. Using OpenSees for structures in fire. Proceedings of 6th International Conference on Structures in Fire, Michigan, 1089-1094, 2010

J. Zhang, A.S. Usmani, J. Jiang, Y.Q. Jiang, P. Kotsovinos, I. May. Development and application of OpenSees for a RC frame in fire. Proceedings of the 19th UK Conference of the Association for Computational Mechanics in Engineering, Edinburgh, 233-236, 2011.

J. Zhang, A.S. Usmani, J. Jiang, Y.Q. Jiang, P. Kotsovinos, I. May. Development and application of OpenSees for a RC frame in fire. Proceedings of the 19th UK Conference of the Association for Computational Mechanics in Engineering, Edinburgh, 233-236, 2011.

thermomechanical

nonlinear

OpenSees

Nonlinear thermomechanical analysis of structures using OpenSees

Thesis or Dissertation

Doctoral

PhD Doctor of Philosophy