Bridges, the most important road infrastructure in construction and operation conditions, are constantly exposed to the crisis of depreciation and destruction. With the reduction of government budgets and the consequent reduction of their maintenance credits, the approach of this crisis to a disaster is implausible. In such a situation, a dynamic and comprehensive system that can appropriately prioritize limited budget allocation is undoubtedly desirable for the trustees. This system is called Bridge Management System (BMS). This research seeks to investigate the capacities of improving the management system of road bridges in Iran. For this purpose, a library study method has been used to examine the findings of other researchers in the field of BMS improvement potentials. The result of this study is the selection of three techniques of project risk management, comprehensive quality management and data mining, whose functions and characteristics to be able to match and improve BMS functions. A field study tested the improved performance of BMS in front of bridge maintenance operators in the country. The final result of the research showed that the proposed improved performance. It has raised the expectations of the operators of the maintenance of Iranian bridges in a general and step-by-step manner. پرونده مقاله

Using of CFRP carbon sheets because of their high strength, lightness and ease of use have been very expanded in retrofitting concrete members. Including shear walls systems FRP can be used in order to rebuild or maintain the strength of an aged structural member. Repairing, or retrofitting of the intact structural member is conducted to enhance the structural resistance that was deteriorated due to the overloading, construction ignorance and so on. In this study, a model of coupled reinforced shear walls with changing the shape of CFRP fibers arrangement under lateral loading is considered. Then, the effect of coupled concrete compression shear wall resistance vary is investigated on the retrofitting. In all stages, the comparison among the proposed arrangement shape of CFRP fibers are accomplished in terms of lateral load carrying capacity of the specimens. Accordingly, the best form of fiber formation is recommended. Finally, it was concluded that the most optimistic fiber arrangement is fully covered and the next choice is vertically covered FRP arraignment. پرونده مقاله

Given the development of construction industry and design and implementation of high rise buildings with complex sections and various geometrical forms, the use of self-compacting concretes has received the attention of construction engineers and provided great advantages. Due to the increasing air pollution in cities, governments encounter the important issue of repelling the pollutants in which construction industry plays a key role; so that recycled concrete has been suggested to decrease the construction pollutants. Therefore, self-compacting recycled concrete can take advantage of the both types of concrete and enormously benefit the environment by decreasing the use of natural aggregates and preventing from deterioration of natural mines The most important properties of good concrete include its workability, strength and durability. The range of these three properties is determined for the concrete made according to EFNARC, ASTM and BS through fresh concrete tests including slump flow, V-funnel, J-ring, L-box, compressive strength, capillary water absorption and water penetration under pressure and the following results are gained. Increasing the amount of recycled aggregates resulted in reduction of self-compacting concrete criteria like slump, J-ring, etc. which indicated decline of plasticity, workability, passing ability and so on and that might be because of grading variations. Compressive strength was dramatically reduced by increasing the amount of coarse recycled aggregate so that compressive strength of concrete specimens declined by 2-10% as the amount of recycled aggregate rose from 25% to 100%. Increasing the amount of recycled aggregates generally enhanced percentage of capillary water absorption; so that according to the results of tests, water absorption rose by 5-15% in specimens by increasing percentage of recycled aggregates, indicating an increase in permeability and a decrease in durability of concrete. The main propose of this article is to determine the optimum replacing percentage of recycled aggregates to find the best compressive strength and durability of self-compacting concrete. Therefore, different samples with replacing recycled aggregates by 0%, 25%, 50%, 75% and 100%, water to cement ratio of 0.35 and 0.45 and different amount of super- plasticizer were. The result shows that by increasing in the amount of recycled aggregates, the strength of concrete decreases while the permeability of concrete reduces. پرونده مقاله

In this paper, load-carrying capacity in steel shear wall (SSW) was estimated using artificial neural networks (ANNs). The SSW parameters including load-carrying capacity (as ANN’s target), plate thickness, thickness of stiffener, diagonal stiffener distance, horizontal stiffener distance and gravity load (as ANN’s inputs) are used in this paper to train the ANNs. 144 samples data of each of this parameters was calculated using SSW simulation in abaqus. Load-carrying capacity of SSW was estimated using radial basic function (RBF) and multi-layer perceptron (MLP) neural networks. Spread parameter in RBF and number of hidden layer, number of neurons in this layers and activation function in MLP optimized using a trial and error method. The results showed that the load-carrying capacity of SSW could estimate using RBF and ANN by 84 and 96 percent of precision respectively. پرونده مقاله

Time-history analysis is defined as a kind of dynamic analysis increasingly used in design of structures and evaluation of existing ones. One of the important issues in the Time-history analysis is selecting earthquake records. In this case, seismic design provisions states that time histories shall have similar source mechanisms, geological and seismological features with region under study. Alborz is one of the highly seismic regions of Iran which records of large events are not sufficiently available. For this reason, the main objective of this research is to modeling strong motion records and comparing those with observed records. For modeling strong motion at a particular site three main elements: regional earthquake source, propagation path effects and local site conditions should consider. In this study stochastic finite fault approach for generation earthquake accelerographs was used. The use of a finite fault model is particularly important in improving the reliability of estimates for large-magnitude events at close distances. Finally after comparing the results, the generated records are found to be consistent with observed records in Alborz region. پرونده مقاله

تحلیل سازه با رفتار واقعی اتصالات آن بسیارپیچیده است و به همین دلیل با تمهیداتی از جمله استفاده از مفهوم خط تیر، به هر اتصال، صلبیت خاصی را نسبت می‌دهند و بدین طریق آنها را دسته‌بندی می‌نمایند. در این تحقیق به بررسی اتصال نیمه‌صلب با ورق‌های سخت‌کننده در قسمت اتصال جان تیر به ستون پرداخته شده است. برای این کار از 64 مدل تحلیلی که در آن ابعاد ورق‌های سخت‌کننده از جمله ارتفاع، عرض و ضخامت تغییر می‌کند استفاده شده است. مشخصات مدل‌های تحلیلی که در نرم‌افزار آباکوس ساخته شده‌اند در همه حالت یکسان است. و در این مدل‌ها ارتفاع و عرض ورق‌های اتصال که جان تیر را از دو طرف در بر می‌گیرند داری 4 حالت متغیر برای ارتفاع، چهار حالت متغیر برای عرض و 4 حالت متغیر برای ضخامت در نظر گرفته شده است. اتصالات تحت آنالیز استاتیکی غیرخطی مدل شدند و نمودار لنگر- دوران برای هر حالت ترسیم گردید. بدین‌صورت رفتار اتصال نیمه‌صلب و تاثیر ورق‌های اتصال جان در عملکرد آن مورد بررسی قرار گرفت. در نهایت با بررسی نتایج رابطه‌ای برای تخمین درصد گیرداری اتصال نیمه صلب ارائه گردید. پرونده مقاله

Concrete materials are exposed to special weather conditions, corrosion and significant damage. For this purpose, the effect of 28-day compressive strength changes on the samples studied in this study was investigated by considering the simultaneous effect of chloride ion penetration and carbonation phenomenon. For this reason, in the first case, the samples are exposed to carbon dioxide once and then to chloride ions. In the latter case, only samples under the influence of chloride infiltration are examined. To make the samples, which include 9 mixing designs, three water-to-cement ratios of 0.35, 0.4 and 0.5 and three percent of 0%, 7% and 10% silica fume have been used. Finally, an optimal model is introduced to predict the compressive strength of concrete containing micro silica exposed to carbonation using artificial neural network. Also, a relation for estimating compressive strength based on the ratio of water to cement and the amount of silica is presented. پرونده مقاله