مقالات رزومه دکتر حسن صالحی

In this study, the numerical investigation of the pre-approved connections of the 10th topic of the National Building Regulations under explosive loading was done. For this purpose, six three-story, two-span frames with different connections were examined. These frames had similar beams and columns, and their connection types differed. The results showed that the frame with a bolted unstiffened extended end-plate connection (BUEEP) had the minimum displacement and optimal performance under explosive loading. Also, the frame with the reduced beam section connection (RBS) had the highest displacement and the weakest performance. Decreasing or increasing the number of floors did not affect the optimal performance of the frame with a bolted unstiffened extended end-plate (BUEEP) connection. To improve the performance of these connections, various methods were investigated. It was found that adding a steel plate with a thickness of 1 cm to the center of the column and the two ends of the beams separately reduced the maximum displacement of the frame by 11 and 5%. Meanwhile, adding a steel plate with a thickness of 1 cm to the two ends of the beams and the middle of the column at the same time caused a 15% reduction in displacement at the level of the third roof of the frame, which is a very suitable method to improve the performance of connections against explosion.

This study aims to enhance the performance of explosion-proof doors by analyzing the structure, arrangement, and features of their stiffeners. Numerous numerical models were developed to assess how the above parameters affect the performance of rectangular doors under blast loads. The modeled doors consist of stiffeners on their inner face that help them absorb energy and reduce displacement. An optimization process was also carried out to determine the best number and thickness of stiffeners that can minimize displacement while optimizing steel consumption. The analysis revealed that using a non-parallel stiffener can decrease the displacement of the door's center by about 30% while maintaining the same weight. Moreover, the optimal number of stiffeners depends on their thickness. If the thickness of the stiffener is less than 25% of the door panel's thickness, seven stiffeners should be used. If the thickness is between 25% to 40%, five stiffeners are optimal. When the thickness ranges from 40% to 60%, three stiffeners are sufficient, and if the thickness is greater than 60%, one stiffener will provide the best functionality for the explosion-proof door.

Self-compacting lightweight concrete (SCLC) is one type of concrete that its usage has widely increased. The use of some additives in the production of SCLC can both reduce its costs and improve its properties. The effects of different cement replacement materials have been studied by several researchers. Jalal et al. (2012) claimed that the use of silica fume could improve the electrical resistance and mechanical properties of self-compacting concrete, and reduce its water absorption. Moreover, the use of silica fume in normal concrete improves the bond between aggregate and paste surfaces, and it has positive effects on fracture toughness, compressive strength and tensile strength (Lam et al., 1998). To simulate the fracture behavior of concrete in numerical models of concrete, depending on the model, some parameters such as fracture energy, fracture toughness and critical effective crack-tip opening displacement ( or δc), which generally are known as fracture parameters, must be determined. In this regard, Peterson (1980) showed that the fracture parameters are significantly affected by water to cement ratio (w/c) and the quality of aggregate. In other words, by reducing w/c or using stronger aggregate, the fracture energy of concrete increases. In this study, the effect of w/c and silica fume on the fracture toughness and fracture energy of SCLC has been investigated. Therefore, by making six mix designs and 126 concrete specimens, fracture parameters, mechanical properties and the workability of fresh concrete were carefully studied. Initially, four mix designs with the w/c of 0.37, 0.42, 0.47 and 0.52 were made. Afterwards, by replacing 0, 5% and 10% of the weight of cement with silica fume, the effects of changing this parameter on the fracture parameters of SCLC were studied.

In this paper, the efficiency of the bedrock grain's characteristics on the performance of its layers was investigated. For this purpose, experimental and numerical studies were performed using ABAQUS software in both static and dynamic conditions. The performances of the geogrid layers in various types of soils by different values of elastic modulus and frictional angles were investigated. It was observed that increasing soil adhesion at a constant concentration, enhanced loading capacity, and reduced the reinforcing efficiency. Study on different soil types by various specifications showed that for soil substrates by values of elastic modulus of 10, 50 and 100 MPa, the effects of the layers of the reinforcement on improving the Settlement were about 75%, 65% and 54%, respectively. In dynamic loading mode, the performance of the reinforcement layers increased compared to static loading, and the improvements of the Settlement were 79%, 72% and 54%, respectively.

Given the sensitive situation of the country and the successive threats, as well as several terrorist acts in the coming years, the need for passive defense is felt at any other time. Therefore, in these cases, the need to protect sensitive resources is essential. Geosynthetics are among the new and efficient materials that, while simple and fast implementation without the need for equipment and specialized people in combination with soil as protective walls, show good performance even compared to time-consuming, costly and time-consuming structures. In this study, the focus is on the deformation of the reinforced earth wall in the face of an explosion. After examining the model by Geostudio / Slope / w geotechnical software in static equilibrium mode, wall deformations were performed by 3D / Abaqus finite element software using MohrColumb behavioral model. The aim of the present study was to investigate the effect of geosynthetics on the deformation of reinforced earth walls against explosion. The results showed that with increasing the distance of the explosion from the wall, the deformations of the wall decrease, but the remarkable point is the rate of this deformation reduction, which increases with increasing the distance of the explosion from the earth wall

One of the most significant concerns of recent years among scientists has been related to waste management actions and policies. Unfortunately, landfills are filled with various debris and demolition from old building including waste concrete, glass, brick, ceramic, and plastic. Waste concrete seems to occupy a large volume of these landfills; thus, they are potentially among the most appropriate choices for recycling process. However, different papers have focused on the impact of recycled concrete aggregates in concrete and in recent years, no specific model has been recommended to predict the behavior of parent concrete in recycled concrete. In this study, a central composite design along with response surface methodology was employed to prepare experimental designs and model the properties of concrete made of recycled aggregates. Effective factors included compressive strength of parent concrete, substitution rate of parent concrete, and value of cement, while the compressive strength, tensile strength, and water absorption of recycled concrete were introduced as goal responses. Based on the statistical analysis, all recommended models were adequate with acceptable coefficient of determination ( ). Response surface and perturbation plots revealed that compressive strength, tensile strength, and water absorption of recycled concretes depended heavily on the compressive strength of parent concrete. Moreover, in order to generate concretes with higher compressive strength than the compressive strength of parent concrete, the value of compressive strength for parent concrete should be above MPa. However, for low-strength parent concretes, substitution rate should be limited in order to reduce undesirable performance. As the compressive strength of recycled concrete aggregates increased from to MPa, the compressive strength of recycled concrete was enhanced by over percent. In this substitution, water absorption reduced over percent. Additionally, when the compressive strength of recycled aggregates was fixed at MPa, by changing substitution rate from % to %, the compressive strength of recycled concrete increased from to MPa. The tensile strength of recycled concrete also was enhanced from to MPa.