پژوهشنامه حمل و نقل
سال یازدهم شماره 3 (پیاپی 40، پاییز 1393)

Nowadays steel-concrete composite members have successfully been used in pier، beam and deck of bridges، and column، beam and slab of high-rise buildings. Due to their considerable energy absorption and dissipation capacity، concrete filled steel tubes (CFST) members have gained popularity in bridge and building construction. Composite members not only have many advantages in the structural construction but also make a significant improvement in the behavior of structure compared with reinforced concrete and steel structures. Some of these advantages include: Easy and fast for erection and fabrication، using standard connection، savings in the construction costs، suitable performance against seismic loading، high loading and ductility capacities (with fewer volume). In this study، efficacy of type، number and location of two stiffening methods have been investigated on the flexural، buckling and ductility behavior of composite columns. It was found that stiffener enhances the ductility، absorbing energy، strength and critical buckling load of composite columns in comparison to columns without stiffeners.

In recent years، some by-products such as crumb rubber (CR) and reclaimed asphalt pavement (RAP) have been used to save money، protect the environment and extend the life of asphalt pavements. Resilient modulus is one of the most important index and property of material for predicting material reaction under repeated or moving load. Also، it is important variable in pavement design methods. In this laboratory research، influence of CR and RAP on indirect tensile strength (ITS) and resilient modulus of hot mix asphalt (HMA) mixtures was investigated. In this research، aggregate gradation #5 (Iran Code #234)، ambient crumb rubber (40 mesh)، three rubber content (0%، 10% and 20% bitumen weight)، four RAP content (0%، 20، 40% and 60% mix weight) and one penetration grade virgin binder (85/100) was used. The results indicated that، as the RAP content increases، ITS and resilient modulus values decreases and rutting resistance increase while، addition of CR in bitumen of mixtures leads to decrease in ITS and resilient modulus values and increase rutting resistance of mixtures.

With regard to global economic growth and application of new technologies to expand public transportation، using of high-speed Rails in the country is an important issue and make the strategic planning a necessity. Meanwhile، analyzing and appropriate interaction with the internal and external environment is one of the factors for getting success in formulating an optimum strategy. In this paper، in order to formulate a strategy for using high-speed Rails in the country، first of all we will study and analyze the documents، the existing reports، and interviews with experts in the field of rail transportation and will obtain a list of strengths، weaknesses، opportunities and threats. At the end، by using the Delphi technique (consensus) all agents were screened and finalized. In the third phase، by using the SWOT model، we will formulate the appropriate strategies for deployment of high-speed Rails. Then، by using a matrix of quantitative strategies (QSPM)، we will prioritize the formulated strategies. At the end، an action plan was proposed. Research findings show that the Islamic Republic of Iran، by employing conservative WO strategies، in order to use high-speed Rails must use the opportunities ahead and overcome the internal weaknesses. Optimal strategies in this regard were developed and proposed.

Bus fleet performance measurement is under scrutiny of the urban policy makers because of the critical need to enhance the service level for the citizens. However، the situations that are involved in bus line efficiency are very important. Historical data of bus line performance are gathered daily by a wireless network in the city. In this study، bus lines’ data are investigated and processed by a hybrid method. Lines’ efficiency is measured by DEA technique، and then hidden rules in the data set are extracted in regard to the efficiency or inefficiency of the bus lines. At the end، the prediction ability of being efficient or inefficient has been evaluated by CART، C5. 0 and ensemble algorithms. The hybrid method has not been used in transportation field before; also the ensemble model that leads to higher accuracy has been used for the first time in this hybrid method. In this way، the combination of DEA and decision tree as two nonparametric tools will result in a road map to help policy makers for efficiency enhancement in urban transportation.

The transportation sector is one of the most basic infrastructures in the country to achieve economic growth and development، and petroleum products are most important production factors in the sector. Due to importance of the transportation sector''s demand of petroleum products such as gasoline، government intervention in the production and distribution، growing consumption and imports of gasoline، in any countries energy planning is inevitable. Therefore، it is essential that policymakers understand the process of production، consumption and importing these products. In this regard، this paper utilizes two approach، multivariate state-space and artificial neural networks models and using data of production، consumption and gasoline imports in the sample (1978-2008)، to estimation of quantities of production، consumption and gasoline imports. Then، the article predicted production، consumption and imports of gasoline for short-term (2009-2011). The results of the paper suggest that artificial neural network model in forecasting in sample; have better performance than the Multivariate State Space model. Finally، the paper presented forecasting of production، consumption and import of gasoline; with combination of forecasts approach، that this forecast is efficient than two above mentioned methods.

Congestion، delay and creation of long queues in urban networks make transportation authorities to take traffic management methods for optimizing the current capacity of infrastructures. One of the effective methods in this case is applying route guidance systems. Information and route guidance systems are a kind of intelligent transportation technologies which aid drivers to choose the proper route to their destinations. In this research، a route guidance system was developed which the operator (Traffic Management Center) can control the network by every level he wishes for. An overlapping parameter was introduced for every route which compares the cost of every route with the cost of the same one in system optimality condition. For modeling purpose، two programming model were applied which the first model produced the inputs of the second model. The second model، considering the overlapping factor and the tolerance limit of the operator، guide the users. In the introduced assignment process، when the overlapping parameter reaches the tolerance limit of the operator، the route will be eliminated from the guidable route set and other routes will be introduced and reachable for users. The developed model is tested for simple illustrative network. Results showed that the proposed pattern has the most effects in operator tolerance period from 1 to 1. 4. When the tolerance parameter of the operator reaches 1. 1، the total travel time of the network is decreased more than 13 percent. Also، results showed that only a little share of users (15 percent of users in most case) in comparison with UE condition will change their routes which promise the problems with disobedience of users and also validity of results.