AMIRKABIR JOURNAL OF CIVIL ENGINEERING (AMIRKABIR)
Year:2014 | Volume:46 | Issue:1|Papers Count:12

Past studies have shown that dam-foundation rock interaction has significant effects on dynamic response of concrete dams. Moreover, several methods have been presented to investigate this subject such as, boundary element approach or the combination of boundary element and finite element procedures. Most of these methods are relatively complicated. Therefore, in the present study, a new computer program has been developed with a simplified approach. In this program, the dam body and foundation rock are modeled by three-dimensional finite element method. The results obtained by the present method (i.e., FE-FE approach) are very similar to the results published by previous complicated methods. Furthermore, this program is able to also utilize damping solvent extraction method. Therefore, the effects of damping solvent extracting on increasing convergence rate for dynamic response of concrete gravity dams has also been studied.

In this study, capability of Artificial Neural Network (ANN) models for synthetic stream flow generation is evaluated. The used generating model was compounded from ANN model and a random component with normal distribution. The multilayer feed forward neural networks and back propagation learning algorithm have been used in model development. Then, long term synthetic stream flow series up to 300 years of daily stream flow, using only observed daily stream flow in Khersan River have been generated. For model assessment, a comparison has been carried out in respect of different statistics of the historical data and synthetically generated data such as Basic Statistics like mean, standard deviation and skewness and series Persistence Statistics like autoregressives that finally show model’s ability for Synthetic daily stream flow Generation.

Nowadays, in the developing and under developing countries industries are developed rapidly. Gathering various industries in one place has significant advantages such as better management, establishing essential foundations with lower costs, controlling the environmental pollutions and creating more competitions. On the other hand, the disadvantaged are generating various wastes in the high volumes. Therefore, the quantity and the quality of the Charmshahr & Salariyeh industrial state are assessed. This state has more than 200 active factories which lead to generate more than 21 thousand tons per year. Hence, AHP technique with the application of TBL method is conducted to choose the most proper solid waste management system for the state. Moreover, the sensitive analysis is conducted too. At end, recycling with the final weight of 0,325 is selected as the most proper scenario and incineration stands at the second place with the weight of 0.243. However, composting and landfilling are chosen as the next strategies with the weights of 0.238 and 0.194, respectively.

The study of stress-strain behavior of high strength concrete confined by transverse reinforcement has been widely considered by various researchers. As a result, various stress-strain relationships regarding columns made of high strength concrete have been presented. Since each suggested model is based on a limited number of experimental data of a researcher, it has often a good prediction on its experimental results but not on other data. In this study, all available models and experimental data presented by other researchers in the field of strength and ductility of columns made of high strength concrete have been collected. Based on the results of these studies and applying Operations Research (OR), an appropriate model is suggested. It is shown that the proposed model in comparison with other models has a very good agreement with experimental results, by using deterministic analysis.

This paper presents a study on moment connection of I-beam to built-up box column using flange plates. In this type of connection, the beam flanges are not connected to the column flange directly. The flange plates are fillet welded to the beam flanges and CJP groove welded to the column flange. To investigate the cyclic behavior of the connection, nonlinear finite element program ABAQUS 6.8.1 is used. Results show that stress in the groove weld between beam flange plates and column flange is high which results in potential of brittle fracture and non-ductile behavior of the connection. To reduce the stress in the groove weld, single and double trapezoidal rib plates are installed on each beam flange plates. The rib plates are groove welded to the column flange and fillet welded to beam flange plates. Results of finite element analysis show that use of the rib plates although have no significant effect on global behavior of the connection but they result in reduction in the stress in the groove weld between beam flange plates and column flange.

Studies on the behavior of soil layers reflect the fact that the soil is generally enter the range of nonlinear behavior during strong ground motions that have received increased attention in recent years. Conventional seismic hazard analysis often assumes a linear behaviour for soil with considering of a generic-attenuation relation. Generally, for site response analysis, the amplification function is required that is depend on dynamic property of different soil layers, are not known for different parts of the world. This paper is aimed at presenting a straightforward approach for estimating seismic hazard curves taking into account nonlinear soil-site effects. This approach convolves numerically the probabilistic seismic hazard analysis (PSHA) at bedrock with the nonlinear response of soil computed via dynamic analysis. Applications of proposed method has been shown for two different sites located in Tehran and Tabriz, one sandy and one clayey. A Monte Carlo based approach was used for characterization of amplification function values along with those of deterministic curved obtained in the study areas. It is concluded that the proposed model can give satisfactory accuracy for predicting seismic hazard curves when there is a lack of detailed information of dynamic soil properties.

Although many researches have been conducted to investigate the behavior of concrete precast structures against seismic loadings, behavior factor of such structures, which is of significant importance in seismic design of structures, have received less attention so far. In this study, three typical concrete precast frames with precast shear walls, consist of 4, 8 and 12 stories with 3 and 5 bays have been investigated numerically to determine the behavior factors. Effects of two types of uniform and triangular loadings, vertical and horizontal connections between panels as well as pinned and fixed connections between beam and column have been investigated in this paper. To determine the behavior factor, nonlinear static (pushover) analysis approach has been used and Perform 3D software has been applied.Results showed that parameters such as uniform and triangular lateral loadings, pinned and fixed connections of beam-column as well as horizontal and vertical connections between panels have minor effects on the behavior factor. Moreover, increasing the number of spans with shear wall decreases the behavior factor. Increasing the number of stories, increases the behavior factor. The results obtained in the present work for 4 and 8 story frames compare well with those proposed in the seismic code 2800 and NEHRP 2003.

Construction industry is one of the most important industries in the world that has a significant role in the development of countries. Therefore, in the recent decade, many countries accomplish extensive researches for growing their share in an international market. One of the economic approaches, which considered for this reason in several industries in the recent years, is the industrial cluster. However, because of the unique nature of construction industry, many dimensions of this strategy have not been clarified within construction industry. One of these dimensions, that have important role in a comprehensive perception of industrial cluster approach in the construction industry, is the construction cluster map.In this article, a comprehensive map for the construction cluster has been established by the use of grounded theory that illustrates vividly, the actors and activity that contribute to construction industry.

There are some kinds of soils in nature which show a significant decrease in volume by increasing the humidity percentage under a fixed pressure. these solis are called collapsible soils. Collapsible soil shows a noticeable decrease in its volume with an increase in its moisture content under fixed stress. This decrease in volume causes irreversible damages to any structures on collapsible soil and the ones which are under construction. The study of the behavioral characteristics of collapsible soil and its stabilization is crucial. The main purpose of this study is stabilizing collapsible soil and increasing shear strength by adding E.M. Super Repair with different combinations. A sample was collected from Hamidiyeh region near Ahvaz. The primary geotechnical tests were done on the sample. Then shear strength parameters were determined by adding E.M. Super Repair with different combinations. The results show this substance improve the shear strength parameters. The most shear strength has been observed in 1% combination.

Ardakan is located in Iran's central desert. Cracking has caused significant damage to buildings and arteries in this region. Different theories have been associated with the explanation of these cracks, the strongest of which is the problematic soils (expansive soils, dispersive soils and collapsible soils). In this respect several geotechnical tests performed on five bores up to 14 meters in depth. To determine the swelling potential of soil, direct (standard A methods of ASTM D4546) and indirect (various criteria including Chen, AASHTO, Kaldveer, Vander Merwe and free swell test) methods were used.It was concluded that soils have moderate swelling potential. This feature in some cases can cause cracks in the structures. It has also been concluded that the dispersion and collapse potential of soil are negligible.

The cone penetration test (CPT) is the most applicable in-situ tests in geotechnical practice, due to its simple, fast, reliable, and economical nature. The scale effects between the pile to resistance and CPT cone is studied by different researchers, so the effects of these factors are not taken in creating a relation between CPT sleeve friction and pile shaft resistance. The main purpose of this research is studying these effects on shaft resistance. The shear strain due to CPT sounding and pile load tests and the scale effect aspects between CPT and pile related to the shear strain levels were studied. Excess pore pressure effects in fine grained soils generated due to the rate of penetration was individually considered.This database consists of 42 case histories of pile load tests including the CPT profile, derived from different sites that have been used for evaluation of the current approaches. In this paper, the proposed method for determining the shaft bearing capacity, with considering scale effects was evaluated and compared with four methods including: Clisby et al. (1978), Tumay and Fakhroo (1981), Price and Wardle (1982), and Takesue et al. (1998). The results of analysis by the proposed method demonstrate good accuracy in comparison with the other methods for estimating the shaft capacity.