Tehran is one of the most densely populated cities in the world and one of the most important problems of it is the lack of suitable land for the building, so there is a strong need to build high-rise buildings. High-rise buildings desperately need to improve the integration, planning and control of construction quality, etc. This has leaded to the creation of innovative and modern techniques in the high-rise building industry that each of these methods has its own advantages and disadvantages, but despite the pressing need, a comprehensive research has not yet done on the appropriate way for high-rise buildings in Tehran. It is tried in this research, given the effective criteria on high-rise building, to select the best option, considering the methods that there is the building possibility in the current situation. In this paper, at first 15 most important effective criteria for decision making to select proper method of high-rise building in Tehran was identified through questionnaire. Then AHP methodology and Expert Choice software was used to choose the best industrial method for high-rise building in Tehran. In this survey the most appropriate method for high-rise building in Tehran was identified in the condition of applying all the identified criteria that they are respectively: tunnel formwork, concrete buildings (traditional), steel bolt and nut, steel buildings with welded joints, Reinforced concrete structures with continuous frame.

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The most important feature of the behavior factor is that it allows the structural designer to be able to evaluate the structural seismic demand, using an elastic analysis, based on force-based principles quickly. In most seismic codes, this coefficient is merely dependent on the type of lateral resistance system and is introduced with a fixed number. However, there is a relationship between the behavior factor, ductility (performance level), structural geometric properties, and type of earthquake (near and far). In this paper, a new and accurate correlation is attempted to predict the behavior factor (q) of EBF steel frames, under near-fault earthquakes, using the genetic algorithm (GA). For this purpose, a databank consisting of 12960 data is created. To establish different geometrical properties of models, 3−, 6−, 9−, 12−, 15, and 20− story steel EBF frames were considered with 3 different types of link beam, 3 different types of column stiffness, and 3 different types of brace slenderness. Using nonlinear time history under 20 near-fault earthquake, all models were analyzed to reach 4 different performance levels. 6769 data were used as GA training data. Moreover, to validate the correlation, 2257 data were used as test data for calculating mean squared error (MSE) and correlation coefficient (R) between the predicted values of (q) and the real values. In addition, the MSE and R were calculated for correlation in the train and test data. Also, the comparison of the response of maximum inelastic displacement of 5 stories EBF from the proposed correlation and the mean inelastic time-history analysis confirms the accuracy of the estimate relationship.

The fact that Gachsaran salt formation is located in the river behind Gotvand Olya dam, Karon River has become more salty. This issue has raised the concern of destruction of agricultural fields located under the dam in scientific associations and media. Irrespective of any political perspective, the present research seeks to investigate this issue from scientific and practical point of view and evaluate the works done by employers and consultants with the aim of finding an effective treatment and examining the reasons for failure and unsuccessful attempts in this regards. In this paper, after introducing the dam project and conducting a comprehensive geological investigation in the determined territory and also introducing the treatment method used by the project's consultant which is based on construction of a clay wall along the salt dome, the sampling of the soil for construction of the mentioned wall and the upstream and downstream water was done. The results obtained from this test and sampling indicate the implausibility and impossibility of the wall and the necessity of investigating and taking prompt actions regarding this issue.