فهرست مطالب

Structural Engineering and Geotechnics - Volume:6 Issue: 2, 2016
  • Volume:6 Issue: 2, 2016
  • تاریخ انتشار: 1395/02/21
  • تعداد عناوین: 6
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  • Mohammad Reza Fadaei Tehrani *, Raheleh Feizy, Homayoun Jahanian Pages 1-8
    This paper presents a simple yet powerful original approach for approximating dispersivity in porous media. The key to this approach is both use of least-squares criterion and image processing technique. Two dimensional transparent models, including horizontal and vertical configurations, under different combinations of grain sizes and pore velocities, experimented. Concentration data were obtained on a 0.5×0.5 mm grid, which represents approximately 1.8×105 measuring points. Estimates of the longitudinal and transverse dispersivity are obtained for each experiment in three time step, and discussed. Acquired results revealed that presented procedure successfully determine dispersivity coefficients and the maximum error of estimation is 4 to 7%. Furthermore, calculated disperssivity varied from 0.001 to 0.003 m corresponding to grain sizes that agree with literature.
    Keywords: disperssivity, dispersion, porous media, least-squares criterion, image processing
  • Vahid Hosseini Toudeshki * Pages 9-20
    This paper presents the results of engineering geological studies of rock blocks along a road tunnel in NW Iran. The tunnel is to cross the Western Alborz Mountain Range through 530 m in length with 11.2 m span and 8 m height. Eocene tuffs and andesites crop out in whole of the tunnel route. Numerical analyses are done using, a 3D stability analysis and visualization program, called Unwedge that studies pyramidal blocks and supplies an easy-to-use, graphical environment for data entry and visualization. The analysis of support pressure and the sensitivity analysis are done in the different units of the tunnel and the most critical mode of joints combination and the most optimal excavation direction in each of the units is determined. From this analysis, it is possible to ascertain the support pressure for stabilize the rock blocks as a function of the trend and plunge of the tunnel axis. Three-dimensional diagrams have been used to illustrate how the support pressure assembly might affect the design of an excavation.
    Keywords: Support pressure, Unwedge, Zaker tunnel, Trend, Plunge
  • Soheil Ghareh *, Seyed Vahid Mojtahed Sistani Pages 21-23
    Nowadays, soil reinforcement using polymer elements have been investigated by a number of researchers in order to increase the load capacity of soils. Reinforcing soils using fibers is a method of soil improvement, which offers a homogenous mixture in combination with soils, regarding their tensile strength. This combination maintains pressure loading capacity and properties in mutual resistant tensile. The present research investigates the effect of crumb rubber bearing the size of 5mm × 5mm and 10%, 25% and 40% volume on sandy soil behavior using large-scale direct shear test (300mm × 300mm × 150mm) under the vertical stresses of 50, 100 and 150kPa. Results showed that the optimum volume percentage of crumb rubber for maximum shear strength is between 20% and 25%.
    Keywords: Soil reinforcement, rubber, large-scale direct shear test, shear strength, vertical stress
  • Bamshad Sadjadi Manizani *, Shahriar Tavousi Tafreshi, Abbas Akbarpour Nikghalb Pages 25-29
    Externally Bonded Reinforcement on Grooves (EBROG) is a new method that has been introduced to postpone or eliminate debonding of FRP sheets from concrete surface in concrete beams strengthened for flexure and increase loading capacity. For strengthening reinforced conceret beams in strructure, use of different types of FRP like: laminate, AFRP, CFRP, and GFRP. By there is some differences between these kinds related to sensitivity to temperature, shear sterength, The aim of the current study is to examine the efficiency of Externally Bonded Reinforcement on Grooves method on Concrete beam's loading capacity when used under multilayers of high resistance AFRP sheet and comparing it with the results of multilayers of low resistance AFRP. For this purpose , beam specimens with dimension 120*140*1000 mm were modeled in ABAQUS program. According to the analysis, loading capacity is increased when used multilayers of high resistance AFRP instead of using multilayers of low resistance AFRP. Finally, diagram shown that use of multilayers of AFRP has better results than use of one layer of AFRP.
    Keywords: High Resistance, Low Resistance, Aramid Fiber Reinforced Polymer (AFRP), strengthening, Externally Bonded Reinforcement on Grooves (EBROG), loading capacity, ABAQUS program
  • Ali Molaei Manzar, Hassan Aghabarati * Pages 31-39
    Dual systems of steel moment frame and reinforced concrete shear wall have combined the advantages of steel frames and reinforced concrete shear wall. These walls have increased the lateral stiffness of steel frames and have reduced seismic demands on steel frames thus providing opportunities to use such system. In this research intermediate dual system of steel moment frame was chosen with intermediate reinforced concrete shear wall in forms of 3, 6 and 9 story structures, similar plan and three manners of burried column in shear wall, non burried column connected to shear wall and non burried column separated frome shear wall using ETABS 2000 software and it was designed according to equivalent static analysis. In order to evaluate effect of connection between RC shear wall and steel moment frame on seismic performance and reduction factor of systems, all structures have been modelled on PERFORM- 3D software and static pushover analysis has done according to the instruction for seismic Existing buildings (360 Iranian code) and FEMA 356. The results of static pushover analysis on structures show that in dual systems of steel moment frame and reinforced concrete shear wall, the model of connection of burried column in shear wall is more regarding its deformability, strength and capacity of energy dissipation and the interaction between frame and wall is also better rather than two types of non burried column in wall. Type of wall connection to frame on reduction factor of dual systems of steel moment frame and RC shear wall has no effect in mentioning structures.
    Keywords: Dual system, Reinforced concrete shear wall, Steel moment frame, Static pushover analysis, Reduction factor
  • Araliya Mosleh *, Hamed Hamidi, Ahmad Nicknam, JosE Jara, Humberto Varum Pages 41-49
    Bridges, as an essential part of transportation system, play a special role in economy, politic and military all around the world. Serviceability of bridges is of high importance especially in emergencies, helping injured people and proportioning transportation after earthquakes. Earthquake regulation codes, normally suggest linear methods to conduct the analysis, and nonlinear analysis is barely used by practicing engineers. In this paper, we analyze a typical concrete bridge located in Iran and use both nonlinear dynamic and static procedures at two hazard levels. This study compares both methodologies, analyze the results and presents some recommendations to reduce the seismic vulnerability.
    Keywords: Concrete bridges, Seismic vulnerability, Nonlinear dynamic analysis, Nonlinear static analysis, Retrofitting