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Journal Cover American Journal of Civil Engineering and Architecture
  [22 followers]  Follow
    
  This is an Open Access Journal Open Access journal
   ISSN (Print) 2328-398X - ISSN (Online) 2328-3998
   Published by Science and Education Publishing Homepage  [72 journals]
  • Assessment of Turbo and Multilane Roundabout Alternatives to Improve
           Capacity and Delay at a Single Lane Roundabout Using Microsimulation Model
           Vissim: A Case Study in Ghana

    • Authors: Osei Kwame Kwakwa; Charles Anum Adams
      Pages: 106 - 116
      Abstract: A single lane roundabout characterized by long queues during morning and evening peak periods was chosen as our study site. The objective of this study was to 1) Model and calibrate the vissim simulation model for the roundabout and 2) to model roundabout alternatives to improve capacity and assess the delay. A two hour video data collection was undertaken on a typical morning peak from which the traffic demand and turning movement data were extracted. The vissim micro simulation model was calibrated using the west approach as the target and the analysis was done for the existing single lane roundabout. A Turbo roundabout and a conventional double lane roundabout alternatives were also assessed. The capacity of the single lane roundabout was estimated as 2990 pcu/h and was performing at an ICU level of service H. Average Delay on the west approach was 232 seconds. The intersection capacity was 4392 pcu/h when the turbo roundabout alternative was assessed. Westbound vehicles experienced average delay of 87 seconds (inner lane) and 74 seconds (outer lane). The capacity of the conventional double lane roundabout was estimated to be 3690 pcu/h. The turbo roundabout concept will deliver a comparatively higher capacity and could be the most effective alternative to reduce congestion and delay.
      PubDate: 2016-5-20
      Issue No: Vol. 4, No. 4 (2016)
       
  • Durability and Fire Resistance of Laterite Rock Concrete

    • Authors: Ephraim M. E; Adoga E.A, Rowland-Lato E. O.
      Pages: 117 - 124
      Abstract: The ability of a structure to retain its structural integrity in adverse conditions of weather and fire out break depends on its durability and fire resistance. This research work investigated these indispensable properties in Laterite Rock Concrete to assess its usability structural concrete. Durability was investigated in terms of water absorption, density, shrinkage and fire resistance. Fire resistance test was carried out using direct fire test. Two mix proportions: 1:2:4 and 1:1½:3 were tested at optimum water/cement ratio of 0.6 and 0.55 for 1:2:4 and 1:1½:3 mixes respectively. From the results, it is concluded that the concrete is durable, environmentally compatible and possesses high fire resistance properties, having satisfied the relevant codes requirements. The 1:2:4 and 1:1½:3 conform to the specifications for grades 15 and 20 correspondingly. Recommendations include specifications for designing structural elements using the Laterite Rock Concrete.
      PubDate: 2016-5-28
      Issue No: Vol. 4, No. 4 (2016)
       
  • Estimation of the Yield Stress of Cement Pastes from Electrical
           Resistivity Measurement

    • Authors: Mbujje Joel Webster; Wei XiaoSheng, Makorogo Javilla Barugahare
      Pages: 125 - 132
      Abstract: This study proposes a continuous method for predicting the yield stress development from mixing until the final setting point. Samples prepared with water to cement ratios (w/c) of 0.3, 0.35 and 0.4 are tested using a vane in cup rheometer, a Vicat needle and a non contact electrical resistivity machine (NC-ERM). Times corresponding to the initial yield stress (ta), a dramatic increase in the yield stress (tb), a maximum torque reading on the rheometer (tc), an initial setting (td) and a final setting (te) on the yield stress-time (τ(t)-t) curve are correlated with the time at a point of inflexion (tP) on the bulk resistivity-time (ρ(t)-t) curve. A quantitative relationship developed between the yield stress and electrical resistivity shows a good agreement with experimental data.
      PubDate: 2016-6-29
      Issue No: Vol. 4, No. 4 (2016)
       
  • Physical, Mechanical and Microstructural Properties of Limestone High
           Performance Concrete

    • Authors: R. Chaid; A. Bali, A. PERROT, M. Mansour
      Pages: 133 - 141
      Abstract: The production of a high performance concrete (HPC) has expanded the scope use of concrete exposed to aggressive environments, thanks to the limited porosity, the durability, the rheological, physical and mechanical properties with the respect remarkable to a conventional concrete. The objective of this study is to develop a HPC incorporating finely ground limestone. The results show that the substitution of one part of cement by limestone contributes more to the improvement of physical, mechanical and microstructural properties of concrete. The couple cement/limestone contributes significantly to a densification of the matrix unlike when the cement is not substituted by addition. The survey also shows that the limestone does not fall into any chemical reaction. However, the development of resistance (physical phenomenon), obviously depends on the quality of hydrates supplied by the hydration, but also how these hydrates are assembled, their arrangement in space and their connections.
      PubDate: 2016-7-5
      Issue No: Vol. 4, No. 4 (2016)
       
  • Assessing Distress Cause and Estimating Evaluation Index for Marine
           Concrete Structures

    • Authors: Masoud Dehghani Champiri; Shahin Sajjadi, S. Hossein Mousavizadegan, Faramarz Moodi
      Pages: 142 - 152
      Abstract: Marine concrete structures may be affected with wide varieties of distresses where they may have different severity and extent. A periodic inspection program should be drawn to assess the structure condition and to specify the maintenance strategies. These inspections are carried out with several destructive and non-destructive tests which are very expensive. This paper tried to classify concrete distresses in the marine environment first and then, provided an evaluation method using an expert system. An extensive literature review, interviews with expert supervisors and a national survey were used to develop this expert system which is capable of determining the health index for concrete structures in marine environment. This marine structure condition index (MSCI) can be applied to assess the structural condition with a visual supervision and elementary measurements. The index is based on expert views with respect to the type, severity and extent of distresses. The specified index provides some appropriate maintenance strategies for the structure. Case studies showed that the proposed method gives better results and removed some deficiencies of some exiting approaches like what US Army Corps of Engineers suggested before.
      PubDate: 2016-7-8
      Issue No: Vol. 4, No. 4 (2016)
       
 
 
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