Several factors and reasons, including correcting errors in bridge design and construction, preventing damage caused by natural and environmental factors, forces caused by earthquakes, or strengthening the bridge structure to withstand more loads, increase the need to strengthen the bridge. Reinforcement is usually applied to a specific element in the bridge, such as the foundation, column, beam head and deck, each of which may be reinforced. Also, from the economic point of view, retrofitting of bridges is generally preferred compared to the replacement and renovation option. Bridges play an important role in rescue operations after an earthquake. It is necessary that these structures have a higher level of protection against seismic attacks. The earthquake identified the weak points of the structure. Bridges are very vulnerable to these attacks due to their low degree of uncertainty. Seismic displacements based on the principles of elastic design are much less than what the structure experiences in a real earthquake. One of the consequences is the falling of the decks due to the loss of the support surface. The decision to strengthen the bridge was made when many bending and shear cracks were created on the king beams of the bridge. The use of FRP profiles can significantly prevent losses caused by corrosion and is a good alternative to traditional methods of strengthening the structure. In this article, the design for the deck of a sandwich panel bridge reinforced with FRP fibers is presented.
Nowadays, the use of reinforced concrete hollow slab system in building structures is widely accepted due to the provision of control criteria, the ability to be used in large openings and flexibility in architectural designs, and it is more responsive in terms of economic efficiency and time management. has it. The use of reinforced concrete hollow slabs is one of the effective methods in styling and reducing the dead load and consequently the earthquake load, and as a result achieving sections with smaller dimensions. The aim of the current research is to study the post-cracking behavior of reinforced concrete hollow slabs under Common loading situations and analyzed using the finite element method. Also, by using the obtained results and comparing them with the behavior of laboratory samples, it is intended to determine the optimal numerical model for predicting the behavior of reinforced concrete hollow slab, and to measure the accuracy of common design relationships. Modeling of hollow concrete slab sample in this study has been done using ABAQUS software, and the results of this study showed; The load coincident with the first crack in the CDP method was obtained for 10.18, 15.2, 34.20, and 44 for the concentrated joint, concentrated grip, wide joint, and wide grip modes, respectively.
In recent decades, various control systems have been studied to reduce the vibrations of structures under dynamic forces. Generally, types of structural control systems are classified into energy dissipation systems and seismic isolation systems. Examples of energy dissipation systems include metallic yielding dampers, friction dampers, viscoelastic dampers, viscous dampers, tunable mass dampers, and tunable liquid dampers. This article investigates the seismic performance of friction dampers and metallic yielding dampers in steel frames, as well as the performance of a two-story steel frame strengthened with metallic yielding dampers and combined with friction dampers. For this purpose, five two-story steel frames with eight-story divergent braces were examined: a frame without a damper, a two-story frame with metallic yielding dampers, a two-story frame with friction dampers, a two-story frame with the first floor having friction dampers and the second floor having metallic yielding dampers, and a two-story frame with the first floor having metallic yielding dampers and the second floor having friction dampers. The results show that the use of dampers increases the energy dissipation of the structure and reduces the maximum displacements induced in the structure as well as the base shear. The effect of metallic yielding dampers on reducing the base shear is greater than that of friction dampers, while the effect of friction dampers on increasing energy dissipation and reducing displacements induced in the structure is greater compared to metallic yielding dampers
Lack of proper municipal solid management in the Northern provinces of Iran has led to damages to the natural resources, health, environment, social and economic conditions. Construction of solid waste processing plants such as compost and incineration, ignoring essential elements in waste management, cannot be as a successful strategy to solve the solid waste problems. Integrated management as a suitable and well-proved solution in many developed countries was proposed for Mazandaran province as a more reliable strategy to replace the existing conditions. In this paper, the results of study conducted for Amol and Noor region have been analyzed. Minimizing waste production, maximizing recycling and reuse, processing organic waste through digestion or composting process, producing refusing derived fuel (RDF) and using it in the waste incineration plants or Neka cement plant and finally disposing less than 10% of the waste in landfill is the proposed solution to improve the existing waste conditions. Implementing the proposed integrated management over a period of 20 years will lead to preventing from economic and environmental damages due to the loss of valuable natural resources and the release of various pollutants from landfills which is evaluated to be equivalent of about 28 billion dollars also, saving resources and energy estimated to be about 38 billion dollars.
The moment frame is one of the most widely used seismic resistant systems in the world, due to its high formability and flexibility, this system causes a lot of displacement in the structure and force exceeding the capacity of the structural components. The bracing system is a suitable method to control the lateral displacement of the structure and the seismic improvement of the bending frame. The new type of bracing system that is used in the design of new systems and the improvement of old structures is non-buckling bracing, and in this research, their effect on the performance of 4, 7, and 10-story concrete moment frames under the Northridge, San Salvador, and Tabas earthquake has been investigated. The research method in this research is analytical-applied, which the results of this study showed; In the 4-story structure, the amount of wasted energy under the 3 considered earthquakes is equal to 0%, 0%, and 1% without buckling braces and 39%, 48% and 50% in the case with non-buckling braces and in the 7- story structure, the amount of energy consumed under the mentioned 3 earthquakes is equal to 0%, 0% and 0% without buckling braces and 40%, 45% and 51% in the case with non-buckling braces and also in the 10- story structure, the amount of energy consumed under the above 3 earthquakes is equal to 1%, 0% and 11% without buckling braces and 35%, 42% and 45% in the case with non-buckling braces. So, it was concluded that the performance of the structure in the case with non-buckling braces is better than in the case without non-buckling braces.
Geopolymer concretes (GPCs) are known as green, environmentally friendly, sustainable concretes in the development of the structural industry with superior mechanical performance and durability compared to ordinary Portland cement concrete (OPCC). This type of concrete emits less CO2 than OPCC and aims for efficient waste management while reducing environmental impacts. In this experimental research, 5 mixed designs were made of GPC based on granulated blast furnace slag (GBFS), which contains 0-8% Nano silica (NS) and 1-2% polyolefin fibers (POFs). A mixed design was also made of OPCC to compare with GPC. The tests of compressive strength, tensile strength, drop weight impact (DWI), Ultrasonic Pulse Velocity (UPV), water permeability and microstructural examination by scanning electron microscope (SEM) images and X-ray fluorescence (XRF) spectroscopy were performed on concrete samples and the results were analyzed and compared. The results obtained in this laboratory research, while overlapping with each other, indicate the superiority of mechanical properties and durability of GPC compared to OPCC.