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This paper presents the flexural response of reinforced geopolymer concrete (RGPC) beam. A commercial finite element (FE) software ABAQUS has been used to perform a structural behavior of RGPC beam. Using parameters such: stress, strain, Young's modulus, and Poisson's ratio obtained from experimental results, a beam model has been simulated in ABAQUS. The results from experimental test and ABAQUS simulation were compared. Due to friction forces at the supports and loading rollers; slip occurring, the actual deflection of RGPC beam from experimental test results were slightly different from the results of ABAQUS. And there is good agreement between the crack patterns of fly-ash based geopolymer concrete generated by FE analysis using ABAQUS, and those in experimental data.

Given the importance of light construction in terms of better performance of structure, in case of earthquake, reduction of life and financial casualties, as well as shortage of studies in this field, the present research studied building non-structural lightweight blocks using lightweight aggregates of Scoria, Pumice and Leca. On the other hand, density, compressive strength, and water absorption volume of these blocks have been investigated in this research in order to replace traditional materials with them. The experiments' results show that, due to hardness and strong texture, high mechanical resistance of their lightweight aggregate Scoria blocks have higher compressive strength and density but lower water absorption volume compared to Pumice and Leca lightweight aggregate blocks. Despite desirable compressive strength and lower density compared to the other two blocks, pumice blocks have higher water absorption volume, and they do not meet standards. This makes them less interesting. Among these Leca blocks with density of 1151.94 (kg/m 3 ) below 2000 kg/m 3 of Iran density standard of 7782 (28-day compressive strength of 2.57 MPa), higher than 2.5 MPa of Iran compressive strength standard of 7782 (and water absorption volume of 282.92 kg/m 3 ) and below 288 kg/m 3 of Iran water absorption volume standard of 7782 (as a non-load-bearing lightweight block), has been recognized desirable.

Various methods are available to reinforce concrete members and structures. Wrapping the concrete beams with composite sheets is one of the suggested methods for increasing the load bearing capacity of concrete beams and specially those containing opening. In this paper, the influence of using two composite sheets reinforced with carbon (CFRP) and glass (GFRP) is studied on increasing the strength of concrete beams having opening. A number of concrete beams with and without openings were modeled in ANSYS and using the nonlinear analyses, the initial cracking load, ultimate failure load, cracking pattern and deflection were determined numerically for each beam. Different wrapping schemes were examined for increasing the load bearing capacity of the opening section and it was concluded that wrapping from both inside and exterior of opening with the mentioned composite patches provide the most enhancement in the opening zone. Also the CFRP patch showed better performance in comparison with the GFRP wrapping.

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Steel moment frame systems, steel plate shear walls and also buckling restrained brace (BRB) are considered as the most widely used seismic resistant systems of the world. Firstly, in this research, in order to validate the finite element models, the tested sample of steel plate shear walls of 4 floors at the University of Alberta, Canada, and the tested sample of buckling restrained brace at the University of Berkeley California, with the software ABAQUS 6.10-1 were used. Then, the obtained results of the test and analysis have been compared. The confirmed models have been used for the analysis of two-dimensional frame of plain and perforated steel plate shear walls with a regular pattern of positing holes in the screen, buckling restrained brace and moment frame of 4 floors.

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In this study, the behavior of two buildings designed with steel structures Buckling Restrained Braced (BRB) and conventional bending frame was studied to analyze their strengths against progressive collapse. The structures were designed and analyzed in accordance with Iranian regulation No. 2800 for the design of buildings. Using nonlinear static pushover analysis, the performance of the structure after removal of the center and the corner columns were investigated and it was demonstrated that removing the corner column provides more critical conditions for the investigated buildings. Furthermore, the use of BRB elements provides better performance for the analyzed buildings due to the ability of BRB in absorbing and dissipating more energy induced from the external loading sources like the earthquake.