navayineya

A large number of bridges and buildings that are currently used, are made of slabs withopening. Some of these buildings and bridges have been severely damaged because of natural disasters such as earthquake, storm and other effects such as materials fatigue and alkaline and corrosive agents.Therefore, retrofitting and strengthening of these structures is essential and affordable. In this research, by applying experimental models, the flexural behavior of reinforced concrete slabs with opening strengthened with different FRP systems and steel sheets have been studied. Eight specimens of reinforced concrete slabs designed according to the Iranian code ABA with the dimensions of 150×45×20 cm were manufactured. In these slabs, the amount of tensile reinforcement was equal to 0.25 ρ b. Two openings across the length of each slab with 10 cm diameter were created. One slab was considered as reference (not strengthened) and seven other slabs were strengthened with CFRP laminates, GFRP sheets and steel sheets, and tested. Forces, strains and deflections were recorded during the tests. The results of this research show that the flexural strength increases about 43% in the strengthened slabs with FRP laminates, about 57% with CFRP sheets, 45% with GFRP sheets and 15% with steel sheets.

In this work, rotational components of ground motion acceleration were defined according to improved method from the corresponding available translational components based on transversely isotropic elastic wave propagation in the soil. With such improvement, it becomes possible to consider frequency dependent wave velocities on rotational components of ground motion. For this purpose, three translational components of El Centro earthquake (24 January 1951) were adopted to generate their relative rotational components based on SV and SH wave incidence by Fast Fourier transform with 4096 discrete frequencies. The translational and computed rotational motions were then applied to the concrete elevatedwater storage tanks with different structural characteristics and water elevations. The finite element method is used for the nonlinear analysis of water storage tanks considering the fluid-structure interaction using Lagrangian- Lagrangian approach and the concrete material nonlinearities have been taken into account through William- Warnke model. The nonlinear response of these structures considering the six components of ground motion showed that the rotational components of ground motion can increase or decrease the maximum displacement and reaction force of the structure. These variations are depending on the frequency of structure and predominant frequencies of translational and rotational components of ground motion.

In recent decades the use of special truss moment frames has been developed as relatively new steel frame systems in high seismic zones. These frames dissipate the seismic energy through the specific ductile parts that are located near the middle of the span of the truss beam. In this study the response modification factor of steel moment frames with specific truss beams due to the ductility and over strength was determined. The analysis was carried out using linear static analysis (pushover). In order to consider the nonlinear behavior of the material in formation of the plastic hinge، it was used the elasto-plastic behavior and it was assumed that the plastic hinge are created at the top and bottom of the column and beam. The analyses are carried out for two types of the frames، Vierendeel and across diagonals frames. These frames are evaluated for two cases، two and three spans، and also for different stories، 3 to 8-story. The results are shown that the response modification factor of the Vierendeel frame is more than the across diagonal frame’s and has a better seismic performance. The results also show that the response modification factor is dependent on the height of the structure، so that this factor is increased with increasing the height of the structure.

Growing population and improvement of living standards on one hand and limited drinking water sources on the other, have forced the related authorities to optimize and upgrade the existing water distribution systems. These networks are normally extensive and costly, in which a correct methodology to keep its performance at acceptable level in needed. In this article, the city of Fariman in the province of Khorassan was selected to carry out the above studies. In this research, the design parameters such as average per capita, water consumption daily water consumption, pick hourly and daily consumption, percentage of leakage and water meter calibration water experimentally investigated. Also the information on the physical condition of existing water distribution system and number of network breakdowns were gathered and analyzed. The obtained design data were implemented and compared with recommended Iranian code of practice, and showed.