نشریه آنالیز سازه - زلزله
سال نوزدهم شماره 2 (تابستان 1401)

In this study, after evaluating the capability of Abaqus software and ensuring the results, two non-reinforced prestressed beams as reference models and 24 reinforced prestressed beams with carbon and glass reinforcing fibers and application of concrete with strength of 30, 40 and 50 MPa and prestressed cables with diameters of 16, 20 and 22 mm were modeled. After numerical analysis of prestressed concrete beams with and without reinforcing fibers, their bearing capacity was investigated. After numerical analysis of prestressed concrete beams with and without reinforcing fibers, their bearing capacity was investigated. It was concluded that in the simple reinforced concrete and prestressed beams, cracks resulting from tensile damage in the middle cross section of the beams with maximum stress are continuously reduced with a gentle slope towards the supports. In simple reinforced concrete and prestressed beams, the highest stresses were created in the tensile reinforcements at the bottom of the beam and in shear reinforcements, the stress get started in the middle section of the beams and exhibited its maximum in the lower part of the beam section. In addition, in simple prestressed concrete beams, the capacity was increased by raising the number of prestressed tendons from 1 to 2 and 3. The capacity of beams with 3 tendons has increased by 79% and 22% compared to the beams with 1 and 2 tendons, respectively. The bearing capacity of prestressed concrete beams with C50 consumption category were increased by 6% and 5% contrasted to the prestressed concrete beams made of C30 and C40 concrete categories, respectively. By comparing the reinforced models using carbon reinforcement sheets in comparison with the glass type, the bearing capacity of beams containing carbon fibers are enhanced by about 12% (on average) compared to different types of glass fibers.

Liquid Storage refers to structures utilized to store water in the water supply and refueling systems of industrial estates and refineries. These structures are also widely used in industrial areas and nuclear facilities. In the field of energy industry and macroeconomics, protection of resources and storage structures is considered as one of the important and strategic necessities. The present research investigated an unburied concrete reinforced liquid storage structure (CRLSS) with dimensions of 1 × 1 × 4 m under impact of blast with different TNT masses of 10, 12, 14, 16 and 18 kg at 2.5, 4 and 5.5 meters at both lateral and upper positions of the surrounding wall of the CRLSS. Load blast enhanced (LBE) and LS-DYNA, a non-linear dynamic software, were applied for modeling and explicit solution modeling was used to model the shock caused by the blast wave. The impact of shock, pressure and damage to the CRLSS has been investigated after validating the numerical method by laboratory studies by changing the distances and masses of TNT in both lateral and upper positions of the CRLSS. The results indicate that the most critical situation is when TNT is in the lateral position at 2.5 meters from CRLSS, and impact of blast shock and pressure on the CRLSS increased by approximately 20%, 30%, 36% and 43% by increasing the amount of TNT to 1.2, 1.4, 1.6 and 1.8 times, respectively. Based on the results, the reduction of the amount of damage and the spread of damage in the body of the CRLSS has occurred with the increase of the height of the fluid

Underground structures are the best options to build command posts, shelters, weapons depots, important equipment, and defense industries. The manner in which a loading is caused by launch of airplane bombs on buried underground structures is among major issues on which relatively few studies have been carried out, and may not be considered in design of such structures. The simultaneous and Multi-step explosions of missile launches from aircraft and drones also affect the buried structural response.  Therefore, in the present study, after verifying the validity of the numerical model with a real model, a comparative study on the effect of simultaneous and multi-stage bombs on response of secure buried structures in soil was carried out using finite element method. This issue has been investigated in four cases with constant burial depth and different explosion location. The results of maximum stresses presented that, in the case of multiple-stage bombing loads, underground structures under study, in all considered situations, experienced more stress than the simultaneous explosive loading mode. The difference of these changes has been observed in some places up to about 15%.

Construction site layout planning is one of the most important and essential early steps in construction management, which significantly influences project’s productivity. Since the tower crane is one of the key facilities on construction sites, optimized planning and managing its operation can improve construction performance. Determining optimal capacity and location of tower crane are complex combinatorial NP-hard optimization problems that are affected by several interrelated factors. This problem cannot be solved using exact mathematical methods on a large-scale site. Therefore, the use of metaheuristic algorithms is necessary in order to solve it. Tower crane’s location has a significant impact on its required capacity and, as a result, on total cost of material transportation, which was not considered in research for a long time. Recently, in a new research, tower crane’s capacity has been considered as a decision variable in the mathematical model. But the problem has been solved on a small-scale and with a precise method. Since the feasible solution space increases on a real-scale site, therefore, using the precise techniques is not practical to achieve the optimal solution. Therefore, it is necessary to utilize meta-heuristic algorithms to solve the problem. Using Genetic Algorithm, this study presents the optimal type and location of tower crane and material supply point as decision variables based on minimizing the total cost of material transportation on the large-scale site. The results indicate that the GA successfully determines the optimal solution, leading to approximately 14% cost reduction compared with when a site layout is decided based on experience.

Global warming and its effects on the environment can be considered as the important crises facing humans. Finding a method to reduce cement consumption can be an effective step in controlling the annual increase in global temperature. In this research, in order to find the optimal mixing design for replacing local mineral pozzolan instead of a part of cement, two mixing projects with four types of 5, 10, 15 and 20 percent by weight replaced a part of concrete cement.The compressive strength and concrete quality tests were evaluated in the specimens. The constituent elements of concrete and the effect of adding local mineral pozzolan were investigated using the XRD analysis, as well as the morphology and microstructural behavior of concrete with the SEM test. The results exhibited that the best replacement value of cement by pozzolan in concrete is equivalent to 15 percent by weight of cement. Pozzolanic samples increase the strength by 24% compared to plain cement concrete (PCC) samples. Optimal pozzolanic reaction reduced the amount of portlandite and calcite in concrete. Also, this pozzolan reduced the pores, increased the improvement and integrity of the interfacial transition zone (ITZ) in concrete in comparison with plain cement concrete. Considering the effects of this pozzolan on strengthening the structure and reducing the consumption of cement in concrete, the studied local mineral pozzolan can be introduced as a green material that reduces cement by increasing the strength of concrete and is environmentally friendly.

One of the new structural systems utilized in high-rise structures is diagrid structural systems. In this type of structural system, the columns are removed and the diagrid members are replaced. In other words, in addition to carrying gravity loads, the diagrid members also control lateral loads and there is no need to design a lateral load-bearing system for the structure. The buildings built with this system, in addition to innovation in the structural system, have a beautiful and unique architectural design. One of the most important and effective design parameters in diagrid structures is determining the angle of diagrid members. This angle directly affects the weight of the structure. In the present research, the angle of diagrid members has been studied and evaluated. For this purpose, a 24-storey building has been analyzed and optimized. In order to optimize the structure, an improved genetic algorithm has been used. In this regard, using the genetic algorithm, the optimal weight of the frame at different angles for the diagrid structural system as well as the structural system with mega bracing is determined and the optimal weight is presented. The weight of the diagrid structure was compared with the weight of the mega bracing system. The results show that the optimal angle of the diagonal members in the mega bracing system is approximately 36 degrees, while this angle is approximately 65 degrees for the diagrid system.

The Internet of Things is a new model known as the Internet of the Future, and its main idea is to connect things to the Internet, which was first proposed by Mark Weiser and introduced by Kevin Ashton. The Internet of Things is a term used to describe a world in which objects can They will be able to interact with other objects by connecting to the Internet or with the help of communication tools and share their information with each other or with humans and provide a new class of capabilities and applications. One of the important goals of the Internet of Things is to make management smarter and improve quality. the Internet of Things and its applications can play a central role in the intelligent management of water, which will ultimately lead to the creation of added value. In this review, an overview of internal researches and experiences in the field of using Internet of Things technology in civil engineering (water and hydraulic structures) such as urban runoff management, flood forecasting and warning, evaporation and transpiration, dam safety, water and sewage industry, smart irrigation, Management of water resource consumption, hydrology (quantitative and qualitative management) of surface and underground water has been done. Since the Internet of Things in civil engineering is one of the newest solutions in providing the possibility of data mining and information processing for the development and improvement of the quality of civil infrastructures, it will be faced with the challenges of its use.