Sharif Digital Repository

Fires in buildings and closed environments are considered as the most important types of fires due to the possibility of the presence of people and the possibility of life-threatening. Understanding and predicting fire behavior is critical to preventing damage. Backdraft is a special phenomenon of fire that occurs in a chamber with limited ventilation. In a closed environment where there is fire, over time, due to the closed doors and windows, the oxygen required for combustion decreases and as a result, semi-combustible materials can be dangerously exposed to the environment with flammable vapors and gases. Fill and when sufficient air reaches this chamber, a sudden explosion or the same... 

Correct and timely extraction of smoke is very important in fire incidents. Statistics show that more than seventy percent of fire casualties are caused by breathing toxic gases. One of the destructive factors in the operation of the smoke exhaust system is the plugholing phenomenon. In this phenomenon, due to the improper design of the ventilation system, the exhaust vent extracts air instead of smoke. The plugholing phenomenon causes the accumulation of smoke in the structure, therefore it is essential to know this phenomenon to prevent it. In this research, the plugholing phenomenon in the smoke extraction process has been investigated by the numerical simulation method. To investigate... 

The severe wildfires in California, Australia, Canada, and Iran have interrupted the power system operation, caused multiple blackouts, took many lives, and caused damages to power grid infrastructure to the extent of millions and billions of dollars. Most of the recent wildfires occur in the distribution system. Therefore, enhancing power system distribution resilience against wildfire is crucial.To this end, two groups of measures are proposed: the hardening of the power network and the operational measures. The past published papers mainly studied the resilience enhancement strategies against wildfire from an operational perspective. There is a considerable gap between the past works... 

Fire is one of the permanent threats due to earthquakes, however in spite of the attention drawn towards design and retrofitting of structures in recent years in our country, no effective steps have been taken for examining design methods and control of the structures’ reactions in case of a fire. One of the reasons for this, is lack of observations and data and also lack of a standard for design of structures that are resistant to fire. Since the connections of beams and columns play an important role in performance of the structures, in this research the behavior of a structure having a semi-rigid connection to an end plate has been investigated by performing an experiment on a scaled... 

Abstract- Due to vulnerability of metallic structures to fire, to have an advance estimate of the behaviour and performance of the structure during fire, can greatly assist the designers to make preparations and take precautionary measures to prevent excessive damage to the building. The study of the behaviour of a structure at high temperatures can be divided into two parts, that of its members, and that of its joints. The survey of the literature reveals that most of the previous work concentrated on the former, and it seems that there has not been much work on the latter. The objective of this project was to study the behaviour of structural joints at elevated temperatures, in general,... 

With the process of achieving a higher state of social development and technological advances, the need for higher and more strict safety standards has been increased. In this regard, it is of great importance to have an accurate understanding of the fire phenomena and its consequences. Among the adverse effects of fire, a significant percentage of the fire fatalities is related to the fire-induced buoyant gases (smoke) flow which can lead to suffocation. Therefore, it is necessary to know the physics of the fire phenomena well. In fire investigation methods, the numerical study is an appropriate choice, because of the lower executive cost (relative to the experimental study) and the wider... 

Fire in Grasslands is one of the most dangerous natural disasters that is uncontrollable at the time of its occurrence and will continue until there is a fundamental change in the conditions of the fire. Fire in Grasslands due to the high density of vegetation can produce a large amount of heat energy in a short time and in a very large area, which alone can cause the spread of fire in Grasslands. Today, numerical studies of fire behaviour and propagation are given more attention than experimental studies due to their lower costs and limitations. In the present study, the numerical simulation of the fire spread with the influence of climate parameters such as humidity, rainfall during fire... 

When a fire breaks out in a tunnel, due to the enclosure of the interior of the road tunnels, hot and poison smoke quickly spreads in the tunnel. This phenomenon, in addition to destroy the tunnel structure, causes a lot of financial and human losses. In recent years, research into fire control has become more important with the occurrence of numerous accidents in road tunnels and fatalities. Longitudinal ventilation is still the main method for controlling smoke distribution in tunnels due to lower construction costs and acceptable efficiency. Numerous studies have been conducted to investigate the effect of different and effective parameters on fire control and smoke emissions in direct... 

Fire is an undesirable phenomenon that causes human and financial losses. This in itself is a dangerous event that becomes even more dangerous in closed spaces. Car fires in underground car parks are no exception. In this research, the fire caused by burning flammable materials inside the car cabin located in a closed underground parking environment and the performance of sprinkler and water mist nozzles in controlling and extinguishing it have been investigated. Based on the broad foundations of various phenomena affecting this problem, including the separation of solid fuels under the influence of heat and oxygen, chemical reactions, radiant heat transfer and change of liquid phase to... 

Steel is a non-combustible material, but at high temperatures, steel structures, due to their diminishing yield strength, undergo a considerable visco-plastic deflection, which results in a reduction in their load bearing capacity. Thus, to increase safety against fire must be considered as an important objective in the design and construction of steel structures. One of the safety measures which can be taken against fire is to increase the resistance of the structure against heat by using heat-resistant coatings. This decreases the rate of transfer of heat to the structure, and must include the ‘structural members’ and ‘structural joints’. Due to the role of structural connections in... 

The reinforced concrete deep beam is a structural member with mostly shear behavior that can be seen in various members such as beams of bridges and tall structures, girder beams, and equipment-carrying beams in industrial structures. Due to the non-linearity of the strain in these members, various parameters are important in their behavior and response, including the compressive strength of concrete, the type of loading, the type and amount of shear reinforcement, and the cross-sectional dimensions. Deep beams' ultimate damage and failure are generally shear, brittle, and sudden. Therefore, considering the importance and sensitivity of these crucial structural members, it is necessary to... 

The use of glass fiber–reinforced polymer (GFRP) bars in concrete structures such as bridge decks has increased notably in recent years due to their unique corrosion resistant properties in harsh environments. Also, hybrid steel-GFRP reinforcement solutions have been proposed to provide higher ductility in GFRP-reinforced concrete structures. This study presents the experimental results of fourteen full-scale reinforced concrete slabs consisting control and fire exposed specimens. Test specimens consisted of concrete slabs reinforced fully with GFRP rebar, steel rebars, or hybrid reinforcements. The test variables included the arrangement of rebars, mechanical reinforcing ratio, and the... 

Concrete, a versatile construction material, combines cement, aggregates, and water to form a composite known for its durability and adaptability in various architectural and engineering applications. Its widespread use stems from its ability to efficiently bear heavy loads while maintaining longevity. However, producing concrete's key ingredient, cement, contributes significantly to environmental harm by emitting substantial carbon dioxide during its manufacturing process. This carbon footprint underscores the urgent need for sustainable alternatives and innovative practices in the construction industry to mitigate the detrimental effects on our planet. On the other hand, understanding the... 

The present study evaluates the effect of connection rigidity on the behaviour of partially restrained frames under fire condition. Since the interaction of members with each other at elevated temperatures, controlled by the connections, has a significant effect on the behavior of the structure, a half-scaled three dimensional one-bay, one-story frame was used as the test specimen. In fact, this study is part of a broader research programme in which identical specimens equipped with similar connections (flush endplate connections) with various thicknesses hence various rigidities are studied. In order to record the deformations of structural members and the rotation of connections, Digital... 

As it is known, one of the dangerous consequences of the earthquake is the possibility of fire. In recent years in our country special attention have been paid to design and retrofit buildings against earthquakes, but have not done to understand the behavior and design concepts of structures against fire. One of the reasons is the lack of information and the absence of a specific standard for design of structures against fire. Since the beam-to-column connections play an important role in the performance of structures, in this study, the behavior of the moment frame with flush end plate was investigated by testing on a small scale structural model (half scale). It is observed that, the test... 

Due to the increased likelihood of fire after earthquakes, it seems retrofitting buildings for fire resistance after retrofitting against earthquakes is a priority. As connections are usually the most vulnerable members of Steel Structures in Fire, the main focus of this research is on the behavior and performance of a particular type of connection. The test sample is in ½ scale. Semi-rigid connections with flush end plate with a thickness of 6 mm and three rows of two bolts were used at each connection. Appropriate ductility of the end-plates observed at the end of test. The test continued for 65 minutes and the furnace temperature reached close to 1200℃ and the total failure did not occurr...