abbas akbarpour

Through recent years, several types of research have been performed about steel plate shear walls numerically, experimentally and a combination of these two methods. Scaled samples have been implemented to make transportation and movement processes easier. However, the accuracy of samples with real scale is of concern. In this research -which has been performed experimentally and by software implementation-, at first, cyclic loading was applied on a single-story, single-span steel shear wall sample made with a one-third scale in the laboratory and then it was modeled in ANSYS and loaded in the same condition. The comparison between these two methods represents an acceptable conformation. After the verification accomplished, various conditions were modeled and analyzed in the software as one-fifth, one-fourth, one-third, one-second, two-third and one scale. The results indicate that averagely, a 25% decrement of maximum shear is observed in the scaled models but the result from contours shows a good conformation in the scaled results and indicates their reliability.

Concrete structures may be exposed to high heat. In such a way that high heat in the vicinity of concrete structures causes damage in concrete. The aim of this study is assessment of effect of electric high heat on the bending capacity, energy absorption, fracture type and crack distribution of circular fiber concrete slab under monotonic loading. The concrete aggregates with a fracture percentage of 45% are from the mines around Tehran and the fibers used in the concrete are of macrosynthetic type. The concrete mixing design was based on the target compressive strength of 45 MPa and the amount of fibers equal to 0.5% of concrete volume. The heating of the concrete samples was done by a 2400-liter device with a power of 90 KW and maximum temperature of 550 degrees Celsius. To perform slab tests, Dartec9600 device was used with monotonic loading at a rate 0.004 mm/s. based on the Experimental studies conducted on the fiber concrete slab, the application of high heat did not cause concrete peeling but it reduced the capacity of the slab by 89.3% and decreased the energy absorption of the slab compared to the control sample. Also, SEM photos have shown the aggressive destruction of macrosynthetic fibers and the creation of cracks under the effect of high heat in fiber concrete.

In recent decades, the coupled Steel plate shear wall system is considered as an efficient lateral force resisting system by engineers and researchers. Different parameters affect the nonlinear behaviour of Coupled Steel plate shear wall system. Other models are produced according to the base model. After verifying the nonlinear behaviour of this system by cross stiffeners on the Coupled Steel plate shear wall, an increase in the thickness of the stiffeners and the thickness of the Coupled Steel plate shear wall have been evaluated. In this study, the effect of the parameters on the initial stiffness, ultimate strength, and energy absorption by the samples have been compared with each other and the base model. The cross stiffeners on the Coupled Steel plate shear wall have also increased the sample's initial stiffness, ultimate strength, and energy absorption. However, the use of stiffeners does not significantly affect the energy absorption by the samples. Stiffeners increase the sample's initial stiffness, ultimate strength, and energy absorption, which has little effect on the energy absorption by the sample.

This research has investigated the improvement of the seismic behavior of repairable systems with a cradle mechanism in steel braced buildings with irregular mass in plan. A new method is used to find a suitable method in a building with a regular plan with asymmetric mass distribution, in order to reduce the adverse effects of the structure and to quickly repair the damage caused to the structure after a strong earthquake. In this method, by creating lifting conditions at the base of braced bay columns and by using energy-dissipating devices in this part, energy absorption and consumption are transferred to this part of the structure and prevent damage to other parts. Based on the results, the effect of taking into account the effects of vertical and horizontal earthquakes in different mass irregularities of structures in the seismic performance of low-rise structures was determined. Also, the irregularities in the numerical model of the structure have a significant effect on the IDA curves. As the height of the structure increases in the four failure modes, the mean probability of fragility of the structures occurs at a lower Sa, which means that the vulnerability of the structure increases. Also, with the increase in height, the slope of Sa reduction in four failure modes becomes milder, and the fragility curves for two IO performance levels and CP performance level have been obtained for all 6 structures. Considering the effect of irregularities, they are significantly effective in the structural failure of structures, so that considering the effect of these irregularities in mass distribution can lead to an increase in the probability of structural failure.

When considering energy efficiency optimization in construction project management, one of the best evaluation criteria is the building life cycle energy analysis; that, includes the embodied energy in the building and the operating energy during the life of the building. The present study consists of two steps; 1- Library, statistical and descriptive study (selection of suitable options for life cycle energy optimization of buildings) and 2- Case study (analysis of embodied energy of construction and operation of the building through modeling in energy simulator software design Builder). The results of the life cycle energy analysis of a real educational building in Tehran with a lifespan of 50 years, taking into account ground heating, in the three states of this building; basic available, optimal and optimal with a green roof showed; That, the amount of life cycle energy of the studied buildings is 51.86, 44.82 and 43.89 GJ / m2, respectively. Also, the annual energy consumption during the operation period of the basic educational building in Tehran was estimated to be equal to 0.80 GJ / m2, although this amount was in the range of values provided in global research, but the amount of energy consumption during the operation period of this building Compared to global cultivars, it is a large and significant amount. The overall results indicated; that, The energy consumption during the life of the studied building in the optimal and optimal with a green roof state was less about 24,220 GJ (equivalent to 3958 barrels of crude oil) and 27,420 GJ (equivalent to 4480 barrels of crude oil), respectively, compared to the existing base state.

Since cementitious materials are brittle, they are prone to cracking. Cracks could be healed via autogenous methods namely healing microcapsules.The objective of this study was twofold. First, microencapsulation of isophorone diisocyanate (IPDI) as a catalyst-free healing agent. Second, evaluation of microcapsules effect on promotion of cementitious materials healing capability. PU prepolymer was synthesized and smoth spherical microcapsules of IPDI with average diameter of 48-62 μm were produced successfully. The microcapsules shell wall thickness varied linearly with microcapsule diameter and so, the shell wall thickness to diameter ratio was constant (~0.04).The microcapsules weight loss in a 6 months period was ~12.47% under ambient conditions. The mortars containg 3% of their cement weight IPDI microcapsules, had up to 74% recovery rate of compressive strength while this rate for control mortars (with no microcapsule) were less than 50%.EDS analysis of healed mortars, showed noticable amount of carbon in the areas of ruptured microcapsules and healed cracks, confirming that healing process had been precisely accomplished according to the theory of self healing assumed.Samples containig micocapsules had higher initial compressive strength in comparison with control ones, indicating that there had been an undesired rupture of portion of microcapsules during prepartion and molding of specimens. This demonstrated need of more studies and work on mechanical properties of microcapsules specially stiffness of those used in cementitious composites.

Iran is considered as one of the most seismically active regions in the world. Therefore, the need for seismic strengthening of the existing structures is essential. One of the suitable methods in seismic reinforcement of buildings is the use of dampers. Dampers are components, which are mostly utilized to increase damping and deplete seismic energy. Numerous studies have indicated that dampers can reduce seismic displacement. In this way, the performance of most of the load-bearing members of the structure remains in the elastic range. In this research, the effect of using slit steel dampers (SSD) on concrete structures was evaluated. Therefore, four models of SSD were selected as following: 3 single slit, 3 double slit, 5 single slit and 5 double slit in three thickness of 6, 8 and 10 mm, which were placed in a concrete frame with a single diagonal brace at the connection of the brace to the column beam. The effects of increasing the number of slits from 3 to 5, from single to double and increasing the thickness were studied. The results exhibited that by increasing the thickness of dampers, the area of force-displacement diagram, stiffness and strength were increased in frames. The frames, which are consisted of double 3-slit dampers presented better performance than 5-slit dampers. So that, the reduction of rigidity of frame with single 5-slit dampers in a thickness of 10 mm, was 4.9% in comparison with double samples. In addition, it is decreased in stiffness by 2.9% and 7.3% for single and double models, respectively

Today, Passive defense is considered as a strategic need in management of construction projects in order to providing a desirable sustainable security. A significant portion of the dam and power plant projects build with underground methods. In addition to the cost of these structures, they have also great importance strategically, so supplying the requirements of passive defense is essential in this project. in this research,According to passive defense purposes and the principles of project management in construction of underground projects trying to present the appropriate method according to the current conditions and technology in the country. Therefore, using multiple sources and the use of questionnaires, suitable materials and procedures in the construction of underground structures analyzed and several measures have been reckon then they have been weighted using quantitative methods and applications of AHP.
Final results prove that using FRCS fiber concrete, FRP materials, Nanomaterials as smart materials and additives for high strength concrete are more preferable than usual and privileged materials for construction of these kinds of structures, and utilizing each of the mentioned materials with different construction methods can provide various options and specific applications.

Vulnerable buildings and their rehabilitation are important problems for earthquake regions. In recent decades the goal of building rehabilitation and strengthening has gained different rehabilitation systems. However, most of these strengthening techniques disturb the occupants, who must vacate the building during renovation. Several retrofitting techniques such as addition masonry infill wall, application of buckling restrained braces and local modification of components has been studied in order to improve the overall seismic performance of such buildings. In response to many of the practical issues and economic considerations, engineers use often convergent unbuckling steel bracing frames as the lateral load resisting system during an earthquake.This kind of bracings increases the hardness and strength of concrete structures.The aim of the present study is the evaluation and comparison of seismic performance and retrofitting of an existing 7-storeys concrete structure with buckling restrained bracings and shear walls by nonlinear static procedure (NSP) and accordance with cod-361. The results show that the buckling restrained bracing, decreased drift to acceptable levels and Structure behaves on the life safety of performance level.