mahbobeh mirzaie aliabadi

Self-compacting concrete is one of the newest types of concrete due to its durability, stability, flowability and resistance. Nowadays, one of the most important concerns in the environment is solid waste disposal. Plastic packaging belts are one of the plastic materials that are thrown away after use and are known as waste, also iron smelting factories are the main source of iron oxide waste production. In this research, based on the idea of using plastic packing belts and iron oxide waste in the design of self-compacting concrete mix with different percentages (0, 0.5, 1, 1.5, 2 percent compared to the weight of cement) and ( 0, 5, 10, 15, 20% relative to the weight of sand) was added as an additive. For fresh and hardened properties of self-compacting concrete tests with and without fibers and iron oxide, slump flow tests, V funnel, L box, J ring, U box and compressive strength, tensile strength, ultrasonic pulse speed, Schmidt hammer, temperature effect They were evaluated on compressive strength and permeability. The results of the tests showed that with the increase in the percentage of fibers and iron oxide waste in self-compacting concrete for cubic samples, respectively, the compressive strength, ultrasonic pulse speed, Schmidt hammer and the effect of temperature on the 1-day compressive strength in 28-day processing from the range of 1.61% - 72.57%, 10% - 57.5%, 3.27% - 9.27% and 5.22 – 20.64% increased compared to self-compacting concrete (control) and also the tensile strength of cylindrical samples in 28 days processing.

Self-compacting concrete is widely used in buildings, bridges, industrial pavements and other structures. Due to the wide use of this material, many researchers have investigated its mechanical properties. Several factors influence the fresh and mechanical properties of self-compacting concrete, and heat transfer is one of these factors. Heat transfer is a vector quantity that occurs through conduction, convection and radiation. Heat transfer to solids is a mixture of molecular vibrations and energy transfer by free electrons. Heat transfer is from the molds to the concrete and the temperature increase of the molds affects the surrounding concrete. Therefore, the heat transferred to the molds from the air and its transfer to the concrete can cause crushing, flaking, cracking and reducing the final strength of the concrete. In this research, the numerical model of heat transfer with different types of molds to self-compacting concrete was investigated with ABAQUS software and the experimental results of the compressive strength of self-compacting concrete in polypropylene and ST37 steel molds. The numerical results showed that the transfer The heat from the polypropylene mold to the general environment of the self-compacting concrete and to its central core was reduced by about 61.50 and 62.66 percent compared to the St37 steel mold, and the average laboratory results of the final compressive strength of the concrete showed that the failure results from the uniaxial compression machine, Concrete in polypropylene mold increased by 8.49% and 7.28% compared to concrete in St37 steel mold during 7-day and 28-day curing. With the results shown from polypropylene mold, the effect of heat transfer, temperature and environmental factors can be seen and It reduces the self-compaction of concrete and its use in concrete structures leads to more durability and increased compressive strength compared to other form.

The aim of this study was to evaluate the optimization of three-dimensional steel moment frames structures with torsional irregularity, via particle swam algorithm under earthquake load. In this way, to produce torsional irregularity, the center of stiffness has been kept constant with symmetrical grouping of the members, and the center of mass was placed with specific distances from the center of stiffness. Besides that, two types of three-dimensional steel moment frames structures have been modeled. The first structure has box-shaped columns which is assessed with 0 Percent, 20%, 40% and 60% torsional irregularity. The second structure includes cross-shaped columns which is evaluated with the same condition as first structure. Particle Swarm Optimization (PSO) algorithm has been used to achieve the best structure in terms of: weight, maximum drift, dimensional fit of joints and strong column to weak beam. In addition, in the optimizing process of elements, the required strength of the sections according to AISC 360-16 is satisfied under the LRFD method. The AISC360-16 database is also used for sections of structures (I-shaped beams, box-shaped and cross-shaped columns). The optimization results demonstrated that the weight of the first structure (box-shaped column) with, 20%, 40% and 60% torsional irregularity was higher in comparison with the regular optimal state with 43.242 ton, to 5.5, 9.9 and 11.3%, respectively. Moreover, the weight of the second structure (cross-shaped column) in same noted condition was 0.31, 9.4 and 11.9% more than the weight of the structure in regular optimal state with 54.915 ton, respectively.

Self-compacting concrete is one of the most High potential Concrete Currently available due to its wonderful fresh and hardened properties. fresh properties of concrete include the ability to pass, flow and stability, and with these properties will increase the efficiency of self-compacting concrete in all stages from making to utilization. One of the most important wastes in the steel industry is the electric arc furnace slag and one of its applications is the use as aggregate in concrete .The steel slag of Khuzestan Steel Company consists of fine and coarse aggregates, and in this research we first seek to design a suitable mix of self-compacting concrete And then we replace the amounts of coarse and fine slag by 10% incrementally as long as the concrete remains self-compacting. Replacement of coarse and fine slag has been possible up to 30%. fresh concrete tests include slump flow, V Funnel, J-ring and L-box which is evaluated according to the EFNARC guideline.. Hardened concrete tests include compressive and Split tensile strength performed on standard cubic and cylindrical specimens after curing saturation of concrete at 3,7,28 days. Replacement of coarse slag up to 30% improves hardened concrete properties, But slight decrease in fresh properties. By modifying the mix design and the use of super plasticizer to 3% by weight of cement The coarse slag has been 100% replaced by coarse aggregate and has achieved good fresh and hardened results. Replacement of fine slag by 10% of fine particle is the most optimal condition for fresh and hardened concrete properties, And replacing more than this percentage will greatly reduce the fresh and hardened properties.

One of the most important challenges facing civil engineering community besides cost, performance problems such as vibration, especially in thin sections, the smooth and concrete movement of reinforced and complex sections, is increased resistance with reducing or not using cement. The purpose of this research is to innovate in Portland cementless concrete industry, which is inspired by geopolymer technology and its incorporation in self-compacting concrete (SCC) to produce sustainable concrete, in order to reduce carbon emission from Portland cement (PC) production. In this regard, the furnaces slag as amorphous (cement replacement) and alkaline actuators are used and laboratory study was performed on the fresh properties (slump Flow, T50, L-Box, hopper V and J rings) and hardened properties (compressive and tensile strength). Results indicate easy filling in narrow sections, improved compression, good bonding strength, reduced maintenance, faster construction speed, about 70% increase in 28-day resistance and 86% in 90-day resistance of Type III geopolymer concrete with respect to Portland cement concrete (reference concrete) with constant grade of 400 kg / m3, Use of industrial waste and reduction of air pollution, Improve mechanical properties (according to statistical results of compressive strengths up to 65 MPa), Reduce the overall construction cost of self-compacting geopolymer concrete in comparison to the rate of acquisition of resistance of conventional self-compacting concrete, self-compacting concrete with different slag percentages, conventional geopolymer concrete and ordinary concrete. Due to the high cost of alkaline activators in the country, lack of equipment and infrastructure for slag powder, insufficient information on the durability of geopolymer concrete is predicted and thereby create new opportunities for the construction industry.

The construction of resistant structures against blast loads and vibration is essential. Structures are vulnerable to the external loads in different areas. The initial purpose of designing against blast loads include life safety and the prevention of progressive, collapse based on economic considerations. Structures with these qualities are of great importance and should be protected against explosion. Structures with sensitive and expensive equipment. Structures with long-term guidance role. Structures that cause disruption when they are destroyed. The clear understanding of any occurrence and its consequences are required in order to provide an assessment. The literature review of designing steel frame structures against explosion is evaluated in the next part. Bogosian et al. [1] have modeled the blast load (300-1000 kips) on a structure, and in their result, there is a graph that shows the relation between the chance of occurring an event with weight and the distance of explosive materials. Liew [2] have modeled a five floors steel frame against blast and fire loads. The study on the columns of the structure has shown that local inelastic buckling in critical sections will occur in high strain rates. Izadifar et al. [3] have evaluated the effects of ductility on the behavior of steel frames against explosion. The graph of force against displacement has been drawn and the parameters of ductility has been studied. An eight-floor steel frame, which has been designed for service load (live and dead load) was evaluated under explosion by Urgessa and Arciszewski [4]. The results of the research show that the joints with side plates exhibit a better behavior than the conventional joints when blasting. They also behave more efficiently than conventional joints because of the use of these joints to move the plastic hinge into the beam. By comparing the behavior of similar joints with differences in the thickness of the bonding sheet, it was shown that doubling the thickness of the bonding sheet reduces the in-plane displacement. Inappropriate design is the main reason for the vulnerability of these structures. The optimal model for performance-based design of steel framework structures resistant to explosion is provided in this study. For the purpose of the study, the authors assessed the three performance levels of IO, LS, and CP. The intended system for structures is the steel bending frame. In the first step, the structures are designed against seismic load for three levels of performance. In the second step, the structures were redesigned against the blast load. In order to investigate the behavior of structures, the following parameters were investigated. Weight of structural materials used Assessment of the designed frames has shown that the weight of structural materials consumed by the specimens against seismic load is less than the weight of structural materials consumed against the blast load. Examine the horizontal displacement of the roofs of the floors According to the results, the horizontal displacement values of the roofs in the frames are lower than the seismic load compared to the explosive load. Check the absolute acceleration of the roofs of the frames The results show that in designing the frames against the seismic and explosive loads, the absolute acceleration of the roofs is reduced from IO to CP level. Also with respect to the amount of explosive and its distance to the frames and the amount of seismic load, it is observed that as the number of floors increases, the absolute acceleration of the roof of the frames is closer to each other under seismic load and explosive load.

Self-compacting concrete (SCC). was developed about four decades before since that time it has been used very scarcely due to a number of problems including : separation, lack of flowability and filling ability, high cracking potential, and thereupon low compressive and tensile strength. In this study, properties of SCC containing viscosity modifying agent, steel and polypropylene fibers were investigated. polypropylene fibers with dosages of 0.1, 0.125, 0.20, 0.150, 0.185, 0.205, and hook end steel fibers with volume fractions of 0.5, 1, 1.5, 0.2 and 2.5 were employed; fresh and hardened SCC were examined. The results of the fresh concrete tests revealed that rise of the both fiber types reduces the slump flow and raises the T50 time. In the V-funnel test, the time shortened with polypropylene fibers up to dosage of 1.25%, and then soars. Growing steel fibers elongate the time of the V-funnel test. Adding both types of the fibers reduces the passing ability of concrete in the L box test. Hardened concrete tests indicated that the compressive strength is falling by rising the dosage of steel fibers. The compressive strength at the age of 7 and 28 days improves up to the polypropylene fiber dosage of 1.50% and then declines. At the age of 90 days, strength trend changes in dosage of 0.1. Tensile strength grows as the both fibers increase. The crack test results show that the length and width of the cracks lower with the growth of the fibers. Adding steel fibers boosts the number of cracks.