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Kheyr Aldin A., Mortezaei A.r.,
Volume 2, Issue 1 (3-2004)
Abstract

Structural walls are used extensively in moderate- and high-rise buildings to resist lateral loads induced by earthquakes. The seismic performance of many buildings is, therefore, closely linked to the behavior of the reinforced concrete walls. The analytical models used in this paper are developed to study the push-over response of T-shaped reinforced concrete walls andinvestigate the influence of the flange walls on laterally loaded walls and nonlinear behavior of shear walls, namely strength, ductility and failure mechanisms. A layered nonlinear finite element method is used to study the behavior of T-shaped and rectangular (barbell) shear walls. This paper introduces a computer program to practically study three-dimensional characteristics of reinforced concrete wall response by utilizing layered modeling. The program is first verified bysimulated and reported experimental response of 3-D reinforced concrete shear walls. Subsequently, a study considering eighteen analytical test specimens of T-shaped and barbell shear walls is carried out. Finally, based on analytical results, a new equation for minimum ratio of shear wall area to floor-plan area is proposed.
Shahriar Afandizadeh, Jalil Kianfar,
Volume 7, Issue 1 (3-2009)
Abstract

This paper presents a hybrid approach to developing a short-term traffic flow prediction model. In this

approach a primary model is synthesized based on Neural Networks and then the model structure is optimized through

Genetic Algorithm. The proposed approach is applied to a rural highway, Ghazvin-Rasht Road in Iran. The obtained

results are acceptable and indicate that the proposed approach can improve model accuracy while reducing model

structure complexity. Minimum achieved prediction r2 is 0.73 and number of connection links at least reduced 20%

as a result of optimization.


H. Bahrampoor, S. Sabouri-Ghomi,
Volume 8, Issue 3 (9-2010)
Abstract

 From the time that civil engineers have used steel in building structures, they tried to increase its strength so as to produce more economic and lighter structures by using more elegant sections. Increase of steel strength is not always useful for all members of a steel structure. In some members under certain conditions, it is needed to reduce the strength as much as possible to improve the behavior of structure. By using very low strength steel according to the Easy-Going Steel (EGS) concept in this research, it is shown that the performance of diagonal Eccentrically Braced Frames (EBFs) improves substantially. For this purpose, a finite element analysis was used to simulate diagonal eccentrically braced frames. Fifteen diagonal eccentrically braced frames were designed through AISC2005. By substitutingvery low strength steelinstead of carbon steel with equal strength in the links, their performance improve fundamentally without any global or local instability in their links.


A. Allahverdi, E. Najafi Kani,
Volume 8, Issue 4 (12-2010)
Abstract

Fast set and high early strength cements containing calcium fluoroaluminate phase (C11A7CaF2) are usually produced by sintering a proportioned raw mix from calcareous and argillaceous components as the main raw materials, at reduced temperatures about 1330 °C. In this work, the possibility of utilizing natural pozzolan as the argillaceous component in the cement raw mix and in order to decrease the sintering temperature of fast set and high early strength cement clinker containing C11A7CaF2 phase has been investigated. The results reveal that the sintering temperature can be reduced to temperatures as low as 1270 °C by utilizing a suitable natural pozzolan and improving the mix burnability. The experimental results confirm the possibility of achieving final setting times as low as 10 min and 3-day compressive strengths as high as 57 MPa


M.e. Poorazizi, A.a. Alesheikh,
Volume 9, Issue 1 (3-2011)
Abstract

Air pollution is a serious challenge in densely populated cities. It poses a significant threat to human health, property and the environment throughout the developed and developing parts of the world. Real-time air quality monitoring and public access to related information are the key components of a successful environmental management. Mashups can be customized to adequately address the monitoring of such geographically oriented challenges. The growth of mashups has been accelerated by Web 2.0 technologies. The integration of Web 2.0 and GIS (Geographic Information System) has been highlighted by the second generation of Internet-based services that emphasizes on online information collaboration and sharing among users. The main objective of this paper is to assess, design and develop a Web 2.0 thin client application called Tehran Air Quality Reporter. The application uses Google Maps API (Application Programming Interface), Web GIServices (Geographic Information Services), and AJAX (Asynchronous JavaScript and XML) to disseminate real-time air quality information through internet. Such information can improve the decisions of the pertinent environmental organizations as well as urban settlers. The software also utilized DOM (Document Object Model) and JavaScript functionalities for handling the response events and providing flexibility and more interactivity. The developed Geo Mashup includes geospatial maps and features, standard business charts, node and link displays, as well as custom visual displays. All visualization components run in any web browsers and provide a user friendly environment.
A. Shariat Mohaymany, M. Babaei,
Volume 11, Issue 1 (3-2013)
Abstract

Since the 1990’s, network reliability has been considered as a new index for evaluating transportation networks under uncertainty. A large number of studies have been revealed in the literature in this field, which are mostly dedicated to developing relevant measures that can be utilized for the evaluation of vulnerable networks under different sources of uncertainty, such as daily traffic flow fluctuations, natural disasters, weather conditions, and so fourth. This paper addresses the resource allocation problem in vulnerable transportation networks, in which multiple performance reliability measures should be met at their desired levels, while the overall cost of upgrading links’ performances should be minimized simultaneously. For this purpose, a new approach has been considered to formulate the two well-known performance measures, connectivity and capacity reliability, along with their application in a bi-objective nonlinear mixed integer goal programming model. In order to take into account the uncertain conditions of supply, links’ capacities have been assumed to be random variables and follow normal distribution functions. A computationally efficient method has been developed that allows calculating the network-wise performance indices simply by means of a set of functions of links’ performance reliabilities. Using this approach, as the performance reliability of links are themselves functions of the random links’ capacities, they can be simply calculated through numerical integration. To achieve desirable levels for both connectivity reliability and capacity reliability (as network-wise performance reliability measures) two distinct objectives have been considered. One of the objectives seeks to maximize each of the measures regardless of what is happening to the other objective function which minimizes the budget. Since optimization models with two conflicting objectives cannot be solved directly, the well-known goal attainment multi-objective decision-making (MODM) approach has been adapted to formulate the model as a single objective model. Then the resultant single objective model has been solved through the generalized gradient method, which is a straightforward solution algorithm coded in existing commercial software such as MATLAB programming software. To show the applicability of the proposed model, numerical results are provided for a simple network. Also, to show the sensitiveness of the model to decision maker’s direction weights, the results of sensitivity analysis are presented..
S. Soudmand, M. Ghatee, S. M. Hashemi,
Volume 11, Issue 4 (12-2013)
Abstract

This paper proposes a new hybrid method namely SA-IP including simulated annealing and interior point algorithms to find the optimal toll prices based on level of service (LOS) in order to maximize the mobility in urban network. By considering six fuzzy LOS for flows, the tolls of congested links can be derived by a bi-level fuzzy programming problem. The objective function of the upper level problem is to minimize the difference between current LOS and desired LOS of links. In this level, to find optimal toll, a simulated annealing algorithm is used. The lower level problem is a fuzzy flow estimator model with fuzzy link costs. Applying a famous defuzzification function, a real-valued multi-commodity flow problem can be obtained. Then a polynomial time interior point algorithm is proposed to find the optimal solution regarding to the estimated flows. In pricing process, by imposing cost on some links with LOS F or E, users incline to use other links with better LOS and less cost. During the iteration of SA algorithm, the LOS of a lot of links gradually closes to their desired values and so the algorithm decreases the number of links with LOS worse than desirable LOS. Sioux Falls network is considered to illustrate the performance of SA-IP method on congestion pricing based on different LOS. In this pilot, after toll pricing, the number of links with LOS D, E and F are reduced and LOS of a great number of links becomes C. Also the value of objective function improves 65.97% after toll pricing process. It is shown optimal toll for considerable network is 5 dollar and by imposing higher toll, objective function will be worse.
M. Abbasi, A. H. Davaei Markazi,
Volume 12, Issue 1 (3-2014)
Abstract

An important factor in the design and implementation of structural control strategies is the number and placement of actuators. By employing optimally-located actuators, the effectiveness of control system increases, while with an optimal number of actuators, an acceptable level of performance can be achieved with fewer actuators. The method proposed in this paper, simultaneously determines the number and location of actuators, installed in a building, in an optimal sense. In particular, a genetic algorithm which minimizes a suitably defined structural damage index is introduced and applied to a well-known nonlinear model of a 20-story benchmark building. It is shown in the paper that an equal damage protection, compared to the work of other researchers, can be achieved with fewer numbers of optimally placed actuators. This result can be important from economic point of view. However, the attempt to minimize one performance index has negative effect on the others. To cope with this problem to some extent, the proposed genetic methodology has been modified to be applied in a multi-objective optimization problem.
A. Gholizad, P. Kamrani Moghaddam,
Volume 12, Issue 1 (3-2014)
Abstract

High performance and reliability of refurbish able knee braced steel frames has been confirmed in previous researches trying to get an optimal design for its configuration. Buckling of diagonal member which affects the hysteretic behavior of KBF under cyclic loadings has not been foreseen in previous evaluations of this system. This deficiency can be improved by utilization of adjustable rotary friction damper device (FDD) as knee element. Diagonal element buckling can be prevented considering a suitable value for FDD sliding threshold moment Mf. Lower values of Mf Lower energy dissipation rate in FDD and this leads to an optimization problem. Nonlinear time history analyses have been performed in addition to lateral cyclic loading analyses to evaluate the response of single story KBF subjected to seismic excitation. Optimal Mf in FDD has been chosen according to these analyses results. Roof displacement and acceleration, base shear and diagonal element’s buckling status have been compared in optimally designed KBF and FDD utilized KBF (FKBF) with different configurations. Nonlinear dynamic analyses have been performed for one, four, eight and twelve story frames under different seismic records with several PGAs. More than 60% displacement response reduction has been earned for the FKBF without considerable increase in base shear.
Sandro Machado, Mehran Karimpour-Fard, Miriam Carvalho, Orencio Villar, Atila Caldas,
Volume 12, Issue 3 (7-2014)
Abstract

Municipal Solid Waste (MSW) materials are among the most complicated materials for geotechnical engineering as their composition includes an organic fraction, which suffers loss of mass over time, and a fibrous part, which acts as reinforcement, governing the MSW shear behavior. Because of these characteristics MSW can be described as a viscous material which shows time dependent behavior. Since the decomposition of MSW leads to gas and leachate generation, the changes in the MSW’s mechanical behavior could be linked to gas emission and leachate production from landfills. This paper deals with the characteristics of MSW materials to provide the necessary data for efficient and safe landfill design, construction and operation. The MSW physical characteristics such as composition, water content and organic content at varying ages, field and laboratory measurements of methane generation and leachate production, MSW compressibility behavior and its shear strength are covered. By presenting these data the authors hope to promote a better understanding of the mechanical behavior of MSW and provide useful data for use in landfill management tasks.
H. Qi, D. Wang, P. Chen, Y. M. Bie,
Volume 12, Issue 3 (9-2014)
Abstract

A structural model for urban arterial road is proposed. It describes the road traffic dynamics in a disaggregated way. The structural model mainly includes: (1) a link traffic model that tracks the traffic waves cyclically. Traffic waves within each cycle are captured by three characteristic points. These points are formed by the encounter of different traffic waves. (2) a proportional line model which is used to split the overall outflow into different turning flow. The model is derived directly from first-in-first-out (FIFO) principle. (3) a spillover component that deals with channelized section queue overflow and (4) a traffic flow performance index component that outputs macroscopic and microscopic level indexes. These indexes include delay, stops, queue length and vehicle trajectory, travel time. The former three can be used in traffic flow optimization and the latter two are valuable in vehicle emission evaluation. Simulation results show that with the increasing of numerical resolution, traditional CTM model gradually converges to our model.
M.d. Martinez Aires, M. Lopez Alonso, E. Jadraque Gago, R. Pacheco-Torres,
Volume 13, Issue 2 (6-2015)
Abstract

Workers who carry out manual rebar tying tasks are exposed to muscular-skeletal injuries associated with the use of manual tools and the movements associated with them (force, repetitiveness and awkward wrist postures). This paper presents a background on musculoskeletal injuries directly linked to manual and mechanical rebar tying method is conducted. The objective of this study is to compare the traditional manual rebar tying method to the innovative mechanical technique. The methodology carried out follows a qualitative and a quantitative analysis of both processes. Firstly, a qualitative analysis is performed by semi-structured interviews to workers. Secondly, a quantitative study is carried out in the region of Andalusia (Spain). This field study includes on-site measurements of lengths of time activities. According to the methodology developed by the International Labour Organization, the work timing is calculated and a comparison is given. Results state that the operators adapt without difficulty to the mechanical method and it could result in better performance, whilst reducing some of the risks deriving from the manual tying technique.
M. Davoodi, M. Sadjadi,
Volume 13, Issue 3 (12-2015)
Abstract

The distinctive characteristics of near-field earthquake records can lead to different structural responses from those experienced in far-field ones. Furthermore, soil-structure interaction (SSI) can have a crucial influence on the seismic response of structures founded on soft soils however, in most of the time has been neglected nonchalantly. This paper addresses the effects of near-field versus far-field earthquakes on the seismic response of single degree of freedom (SDOF) system with considering SSI. A total 71 records were selected in which near-field ground motions have been classified into two categories: first, records with a strong velocity pulse, (i.e. forward-directivity) second, records with a residual ground displacement (i.e. fling-step). Findings from the study reveal that pulse-type near-field records generally produce greater seismic responses than far-field motions especially at high structure-to-soil stiffness ratios. Moreover, the importance of considering SSI effects in design of structures is investigated through an example. Finally, parametric study between Peak Ground Velocity to Peak Ground Acceleration ratio (PGV/PGA) of pulse-like ground motions and maximum relative displacement indicate that with increase in structure-to-soil stiffness ratios, earthquakes with higher PGV/PGA ratio produce greater responses.


N. Kaid, M. Cyr, H. Khelafi,
Volume 13, Issue 4 (12-2015)
Abstract

The paper presents the characterisation of an Algerian natural pozzolan (NP) intended to for use in cement-based materials. The experimental programme was based on different tests on paste and mortar. The pozzolanic activity was assessed by the means of lime consumption over time of mixtures of lime-pozzolan (75% NP and 25% Ca(OH)2, water-binder ratio of 0.45). The degree of reactivity was assessed by observing the crystallographic changes (XRD) and lime consumption (TG) up to 1 year of hydration. The effect of NP on cement-based mixtures was based on the measurement of the water demand and setting time of pastes, and on the compressive strength of mortars, up to one year. The replacement rates of cement by pozzolan were 5, 10 and 15%. A superplasticizer was used (0, 1, 2 and 3% of the binder mass). A calculation of the carbon footprint was investigated in order to assess if the natural pozzolan could be considered as eco-efficient when used in replacement of the clinker. The results showed that NP had a medium pozzolanic reactivity and with a medium-low silica content. The use of NP usually led to a small increase in the water/binder ratio (up to 10%) to maintain constant workability. The setting time was also increased by around 20%. Nevertheless, strength tests showed that the pozzolan had sufficient activity to counteract the water demand, since long-term compressive strength of the binary system (cement + pozzolan) were higher than those of cement alone. The use of NP in replacement of clinker involves a reduction in CO2 emissions for transport up to 1800 km, which is compatible with sustainable development. The results are most promising from both a performance-based and an environmental point of view


Mr. L. Yanlong, Mr. L. Shouyi, Mr. Y. Yang, Miss T. Xing,
Volume 13, Issue 4 (12-2015)
Abstract

This study simulates the temperature field and temperature stress of concrete face slabs, considering the cold waves that occur during construction as well as the contact friction between the face slabs and the cushion layer. The results show that when a cold wave occurs during construction, the surface and center temperature of the face slabs continually drop with the outside air temperature, with the surface temperature drop being the largest. In addition, the surface and center of face slabs are subjected to tensile stress, with the maximum principal stress on the surface being greater than that on the center. The maximum principal stress of the surface and center occurs at approximately half of the dam height. This study also examines the surface insulation of concrete face slabs. Surface insulation can significantly improve the temperature drop range and the maximum principal stress amplitude caused by the cold wave. A stronger heat preservation results in smaller tensile stress and an increase in the amplitude of face slabs.


L. Zeng, Q. Zhou, Ch. Xu, Y. Wu, X. Tu,
Volume 13, Issue 4 (12-2015)
Abstract

To study seismic performance of concrete-encased composite columns with T-shaped steel cross-section, twelve half-scale columns were tested under quasi-stastic cyclic loading. The result indicates that concrete-encased composite columns with T-shaped steel section possess good seismic performance. The failure modes include bending failure, shear-bond failure, shear compression failure and shear-composition failure. Unsymmetrical phenomenon of positive and negative hysteresis loop was shown evidently. Span ratio has a great influence on failure mode. The ductility performance decreases with increasing of axial compression level. As stirrup ratio increases, ductility and bearing capacity of columns are improved greatly, and energy dissipation capacity after yielding is enhanced. Cross tie can enhance ultimate bearing capacity, and lower strength attenuation and stiffness degradation on the later loading stage


H.s. Qi, Y. Y, Dian Hai Wang, Y.m. Bie,
Volume 13, Issue 4 (12-2015)
Abstract

Abstract: Gridlock is an extreme traffic state where vehicle cannot move at all. This research studies the development of gridlock by theoretical and numerical analysis. It is shown that the development of gridlock can be divided into several stages. The core of the development is the evolution of congestion loop. A congestion loop is comprised of a number of consecutively connected spillover links. The evolution of a congestion loop always tends to be stable, i.e. the state of all related links tends to be identical.. Under the stable condition, traffic states of all links are identical. A novel concept, “virtual signal” is proposed to describe the queue propagation and spillover during the stabilization. Simulation results show that congestion propagates in an accelerated way. The prevention of the first congestion loop is crucial. The achieved results have potential use for future network traffic control design and field applications


Guray Arslan, Muzaffer Borekci, Muzaffer Balci, Melih Hacisalihoglu,
Volume 14, Issue 3 (4-2016)
Abstract

The contribution of concrete to inelastic deformation capacity and shear strength of reinforced concrete (RC) columns failing in shear has been investigated extensively by various researchers. Although RC members are designed to have shear strengths much greater than their flexural strengths to ensure flexural failure according to the current codes, shear degradation of RC columns failing in flexure has not been studied widely. The aim of this study is to investigate the shear degradation of RC columns using finite element analyses (FEA). The results of FEA are compared with the results of experimental studies selected from literature, and it is observed that the lateral load-deflection curves of analysed columns are compatible with the experimental results. Twenty-six RC columns were analysed under monotonically increasing loads to determine the concrete contribution to shear strength. The results of analyses indicate that increasing the ratio of shear to flexural strength reduces the concrete contribution to shear strength of the columns.


Dongfang Ma, Fengjie Fu, Weiming Zhao, Dianhai Wang, Sheng Jin,
Volume 14, Issue 5 (7-2016)
Abstract

The purpose of this paper is to improve the intelligence and universality of classical method for gating control in the SCOOT system. Firstly, we introduce a method to identify spillovers, and use the occupancy threshold for spillover recognition to trigger this special control logic. Then we present an influence rate model for links upstream of the bottleneck link, and a share ratio model for the downstream links, after analyzing the interrelationship of the traffic flows among adjacent traffic links. With known threshold values for the influence rate and share ratio, we propose a rule and process for selecting the intersections that should be included in the sub-area of the gating control. Thirdly, we determine total capacity adjustments for the incoming and outgoing streams of bottleneck links, with the aim of dissipating the queue to a permissible length within a given period of time. After that, the apportion models for the total adjustments among different paths and links are presented, along with the correlation coefficients of the traffic flows between the bottleneck link and the other links. Next, we ascertain the capacity decrements and increments for the gated and benefiting streams, and define the optimization schemes so as to calculate splits for the gated and benefiting intersections. Finally, we evaluate the advanced method using a VISSIM simulation. The results show that new control method brings significant and positive effects to the bottleneck link itself and to the entire control area.


Onyebuchi Nwabueze Mogbo, Balkiz Yapicioglu, Ibrahim Yitmen,
Volume 15, Issue 5 (7-2017)
Abstract

There are challenges and opportunities of deploying policies for transport infrastructure improvement in developing countries. Transport infrastructural development remains a major tool for achieving the aspirations of the newly introduced economic principles of the Federal Government of Nigeria. This study investigates the impact of innovative strategic approaches for improved transport policy and how the strategies are well incorporated to solve the problems faced in the infrastructure sector in order to enhance improved economic growth. The research involves a questionnaire survey conducted to key stakeholders in Nigerian six states. The study was focused on the stakeholders selected from the public entities, private clients, consultants, and contractors operating within the Nigerian construction sector. Based on the empirical data, the specific ways in which innovative strategies for transport policies affect infrastructure development contributing to sustainable economic growth have been shown. The findings contribute to the fields of innovative strategies for transport policies in infrastructure development by linking various aspects of innovative strategies for transport policies and infrastructure development and their interrelationships to sustainable economic development from stakeholders’ perspective. The results show that variables of innovative strategies in transportation and transportation infrastructure improvement have different roles and significant positive impact on sustainable economic development.



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