فهرست مطالب mahdi eghbali

Optimal use of materials in the construction of structures is one of the main goals in any design. Because the construction of building structures is costly for their builders, therefore, structures and buildings that are economically justifiable and appropriate and meet the requirements of the criteria are more welcome. On the other hand, maintaining the performance of structures in earthquakes plays an important role in ensuring safety and reducing earthquake damage. Optimization of frames reduces sections, stiffness, and strength of components, and as a result, the performance of these frames against earthquakes has been questioned by researchers. In this research, the performance level of optimized steel moment frames with metaheuristic algorithms has been evaluated. For this purpose, the seismic performance of five-story steel moment frames with different geometric characteristics has been optimized and seismically evaluated using Particle Swarm Optimization (PSO), Charged System Search (CSS)Ant Colony Algorithm (ACO) and Genetic Algorithm (GA). The results of studies show that the optimized frame based on the Charged System Search algorithm has lower weight and lighter sections, and the seismic behavior responses of the frames are obtained faster. In terms of performance levels, the total number of collapse plastic joints in the Particle Swarm Optimization (PSO) was higher than other methods. Therefore, this algorithm can also be proposed as a suitable proposal for the optimal design of similar frames.

Seismic Resilience evaluation is a new approach and is defined to promote creating a more resilient society against natural hazards. Building cities resiliently against these hazards is crucial in order to reduce seismic vulnerability and for proper risk management during the occurrence of coming destructive events. Today, one of the most important hazards, threatening many cities is the occurrence of coming earthquakes. Therefore, by administrating the concept of resilience in cities, the effects of destructive earthquakes can be alleviated and help cities to return to pre-event conditions. In this paper, in order to learn more about the concept of urban resilience and its quantification method, districts 1 and 3 of Zanjan city are selected as the case study, and are compared with each other in terms of resilience parameter. The model used in this study is based on the resilience indicators that the weight of them was obtained by analytical hierarchy system and spreading the questionnaire among experts and then, performing statistical analysis on the data derived from these questionnaires. Finally, the final rate of urban resilience against earthquakes in these areas was calculated using the current relationships in the literature. The results show that the final rate of resilience in districts 1 is 0.432, while it is 0.392 for region 3. Thus, by quantifying resilience, this issue will be more understandable to officials, individuals, policymakers and engineers who are involved in these areas and help them to look for viable and long-term solutions to enhance the urban resilience against earthquakes.

In this study, the seismic performance of steel special moment frames under the far field records with and without viscous dampers using FEMA P-695 has been evaluated. 4,8 and 12 story frames based on ASCE 7-10 ,AISC 360 have been designed considering viscous dampers features for a specific damping ratio of 15% (4,8 storey) , and 20% (model 12). Frames with dampers and without them with centralized plastic joints have been designed in opensees software with Bilin cyclic behavior. The frames have been scaled and analyzed based on non-linear incremental dynamic analysis (IDA) using 44 acceleration record of far field in a wide area as well as of seismic intensity. Seismic performance of the above mentioned frames has been offered in case of the probability of collapse, based on probabilistic analysis of seismic fragility. The results point out that in steel frames with viscous dampers at the probable level of 50% the collapsing capacity have raised up to 28%,88% and 74% relating to middle curve of non-linear incremental dynamic analysis. It has also been shown that the design of buildings with viscous dampers with 75% base cut have significantly influenced the reduction in the building weight and its costs as well as in the improvement in technical behavior and criteria.

The first and the most important step in preparation of seismic retrofit plan for existing buildings is the analysis of their vulnerability by conducting retrofit studies. However, most of the existing buildings in Tehran are in urgent need of retrofit studies due to reasons such as high seismicity, upgration of building and seismic codes, the abundance of old buildings and so on. In these studies, it is very important to identify the seismic status of the buildings which are in the first priority of seismic retrofit, especially the ones with public use like schools. A seismic risk prioritization technique for steel buildings is proposed in this paper, using a risk assessment hierarchical structure and fuzzy inference system. Afterward, this technique is applied in a case study, validating the results obtained for the steel buildings of the schools in Tehran. At the first of the prioritization process, the required information of the buildings is classified according to the designed hierarchical structure; Then, after quantification of the qualitative data and the fuzzification, the data are modeled, evaluated and defuzzificated based on the fuzzy inference system; This process is performed for all stages of the hierarchical structure to obtain the seismic risk parameter. After the qualification, this parameter indicates the risk of buildings and their requirement for retrofit or rehabilitation. The results that are distinguished by urban districts, determined the high-risk steel school buildings requiring retrofit studies and have shown the role of each effective parameters on the seismic risk of the buildings.

One of the important steps in seismic collapse assessment of structures by using nonlinear dynamic analyses is the appropriate selection of ground motion records. Epsilon (εSa), eta (η), and gamma (γ) for long-period structures, are proxies that have been recently proposed for Ground Motion Record Selection (GMRS). In this study, two parameters, named γs, are proposed, which have considerable correlation with the collapse capacity of short-period structures having fundamental period less than 1 s. One of these parameters is a linear combination of εSa, epsilon of Pseudo Spectral Acceleration (PSA) at 1.5 times of the fundamental period of the structure (εSa(1.5T1)) and εPGV. The other one is a linear combination of εSa, εSa(1.5T1) and epsilon of spectrum intensity, εSI. To obtain and optimize γs, the Particle Swarm Optimization (PSO) algorithm is applied. Since the parameters proposed as γs have significant correlation with the collapse capacity of short-period structures, they can be used as efficient proxies for GMRS in seismic collapse assessment of short-period structures. The results show that GMRS using γs leads to reduction in the dispersion of structural collapse capacity in comparison with GMRS based on εSa or η.

Many of the existing buildings are made and designed in according to Standard No.2800 (1st Edition). in recent years Increasing in earthquake engineering knowledge and changing in design criteria regulations and seismic evaluation has caused that the existing structures meet local or general deficiencies in seismic requirements. Therefore, the identification and development of appropriate methods is necessary for seismic rehabilitation of existing structures and providing levels of design performance. In this study, the nonlinear seismic behavior of six steel buildings with steel moment frame systems that have modeled in 4, 8 and 12 stories designed according to the criteria of the First Edition 2800 Standard and Publication 519 and has been investigated using nonlinear static analysis. The evaluation results indicate that the existing steel moment frames that are designed according to the Standard No.2800 (1st Edition) cant provide Stiffness and ductility requirements of the Standard No.2800 (3rd Edition) and FEMA356 and must be rehabilitated. The frames Improved by concentrically steel braces, increases stiffness and reduces lateral displacement however, due to buckling of the compression braces, structures suffered a sudden drop in strength and its behavior is not ductile. The use of eccentrically braces due to concentrated plastic deformation in link beams and elastic braces, structural behavior is more ductile in comparison with concentrically braced frames method. The use of buckling restrained braces, due to compressive brace is not buckling and yields in tensile, has caused increase in stiffness, strength and ductility of structure and has improved structural performance in comparison of concentrically braced frames .

Scheduling is an important subject of production and operations management area. In flow-shop scheduling, the objective is to obtain a sequence of jobs which when processed in a fixed order of machines, will optimize some well defined criteria. The concept of transportation time is very important in scheduling. Transportation can be done by robots. In situations that robots are used to transport materials (material handler), breakdown of the machines and robots have a significant role in the production concern. This paper deals with minimization of the total elapsed time for flow shop scheduling problem (number of machine=3) in which the effect of machine and robots breakdown interval are considered simultaneously. Furthermore, by providing an example, the proposed algorithm is described. A summary and future works conclude the paper

Identification and determination of products and their quantities according to available resources are called Product Mix Problem in manufacturing plants. There are many methods for solving these problems. One of these methods is Theory of Constraints which is easy to use and understand. But unfortunately, it can’t solve multi bottleneck problems, so it doesn’t have sufficient efficiency when introduce new product. Consequently Revised Theory of constraints was proposed to solve these problems. This is one of the best methods that provide the same results as ILP in most of the cases. But in this algorithm all parameters are certainty. However, in the real-world, such parameters like capacity and demands are uncertainty. In this situation, fuzzy set theory can be used as an effective tool. So In this paper, an algorithm based on RTOC and fuzzy logic is proposed for solving Product Mix Problems with fuzzy capacity and fuzzy demand.This algorithm is more flexible and popularized than other methods which are used for solving fuzzy product mix problems.

The present study investigated the effects of intra-dentate gyrus microinjection of naloxone (an opioid antagonist) and thioperamide (an antagonist of histamine H3 receptors) in the formalin test in rats. Subcutaneous injection of formalin (50 μl, 2.5 %) in the ventral surface of right hind paw produced a biphasic pattern (first phase: 0-5 min and second phase: 15 - 60 min) of licking/biting and shaking of the injected paw. Intra-dentate gyrus microinjections of thioperamide (2 and 4 μg) significantly (P < 0.05) suppressed the pain responses. Microinjections of naloxone (1, 2 and 4 μg) alone into the dentate gyrus non-significantly increased the intensity of pain. Pretreatment with naloxone (4 μg) significantly (P < 0.05) reversed the antinociceptive effect of thioperamide (4 μg). The results indicated that at the level of the dentate gyrus, blockade of histamine H3 receptors with thioperamide produced an analgesic effect. This thioperamide-induced antinociception may be mediated through the endogenous opioid system.

In order to determine calcium (Ca), magnesium (Mg) content and total antioxidant capacity (TAC) of seminal plasma in buffalo and to study their associations with the semen characteristics, 54 semen samples were collected from 10 buffalo bulls; semen quality was evaluated, seminal plasma was then harvested by centrifugation and its Ca and Mg content were estimated and its TAC determined. The Ca and Mg content of the seminal plasma (Mean ± SEM) were recorded as 22.36 ± 0.52 mg dl-1 and 11.94 ± 0.36 mg dl-1 respectively, while, its mean TAC value was 1.50 ± 0.02 mmol L-1. The mean Ca value was highly associated with sperm progressive motility, gross motility, viability (P = 0.000 for all), negatively with semen volume (P = 0.01), and with Mg and TAC values (P = 0.000 for both). The mean Mg values was highly associated with sperm progressive motility, gross motility and viability and seminal plasma Ca and TAC (P = 0.000 for all) and negatively associated with semen volume (P = 0.014). The mean TAC values was highly associated with sperm progressive motility, gross motility and viability and seminal plasma Ca and Mg (P = 0.000 for all). For further clarification of these associations, the data was categorized in three groups of excellent (Ex, >90% motile, n = 33), good (Go, 80-89% motile, n = 15) and moderate (Mo, <79% motile, n = 6) according to their percentage of sperm motility. The mean progressive motility in Ex group was 92.24 ± 0.51%, in Go group it was 81.66 ± 0.62 %, and in Mo group it was 71.66 ± 1.05 %. The mean Ca, Mg and TAC values were respectively recorded as 25.12 ± 0.29 mg dl-1, 13.78 ± 0.20 mg dl-1, and 1.57 ± 0.009 mmol L-1 in Ex, 18.74 ± 0.63 mg dl-1, 9.14 ± 0.33mg dl-1, and 1.42 ± 0.044 mmol L-1 in Go, and 17.34 ± 0.18 mg dl-1, 8.06 ± 0.25 mg dl-1, and 1.23± 0.05 mmol L-1 in Mo groups. The associations in groups are discussed. These results show that seminal plasma Ca and Mg content and TAC are associated with semen characteristics, and synergistically have an effect on motility and viability of the spermatozoa after ejaculation, which are important factors in semen fertility.