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Rassouli B.,Islamic Azad University at Tehran | Shafaei S.,Islamic Azad University | Ayazi A.,Islamic Azad University at Tehran | Farahbod F.,Housing & Urban Development Research Center
Journal of Constructional Steel Research | Year: 2016

In the present study, the behaviour of concrete stiffened steel plate shear wall (CSPSW) using precast light weight-concrete panels is experimentally and numerically investigated. Three one-bay one-story CSPSW specimens were designed, fabricated, and tested. The steel materials and dimensions of all specimens were the same; however, their precast concrete panels were different. One of the specimens had a precast normal-weight concrete panel on one side of the infill steel plate; on the other hand, another specimen had a light-weight one. The third specimen had two light-weight concrete panels on both sides of the steel plate. The quasi-static cyclic test results indicate that CSPSW with a light-weight concrete panel is a reliable lateral load-resisting system for steel structures. In addition, the shear capacity of specimen with light-weight concrete was approximately similar to specimen with normal-weight one. Therefore, it can be inferred the new system is able to reduce the seismic mass and improve the behaviour of steel structures. In this study, the light-weight concrete panel was 36% lighter than normal-weight panel. Based on the test data, specimens could tolerate high inter-story drift between 5.04% and 6.24% until the shear capacity decline in 80% of the maximum shear load recoded in the test. It should be mentioned that the infill steel plate of CSPSW undergoes entirely inelastic deformation and dissipates significant seismic energy through large lateral displacement. © 2016 Elsevier Ltd


Ziari H.,Iran University of Science and Technology | Sobhani J.,Housing & Urban Development Research Center | Ayoubinejad J.,Iran University of Science and Technology | Hartmann T.,University of Twente
International Journal of Pavement Engineering | Year: 2015

Prediction of pavement condition is one of the most important issues in pavement management systems. In this paper, capabilities of artificial neural networks (ANNs) and group method of data handling (GMDH) methods in predicting flexible pavement conditions were analysed in three levels: in 1 year, in 2 years (short term) and in the pavement life cycle (long term). For this purpose, three effective groups on pavement condition including traffic conditions, environmental changes and pavement structures were studied and nine effective variables were selected as input variables. International roughness index (IRI) was also used as the indicator of pavement performance. Various ANN structures and GMDH models in partial description configurations of 1st, 2nd, 3rd and 4th polynomials were formed and examined. Results indicate that while ANN models predict future condition of pavement with high accuracy in the short and long terms, GMDH models do not have accepted accuracy. © 2015 Taylor & Francis


Heshmati A.,Iran University of Science and Technology | Tabibnejad A.,Iran University of Science and Technology | Salehzadeh H.,Iran University of Science and Technology | Tabatabaei S.H.,Housing & Urban Development Research Center
KSCE Journal of Civil Engineering | Year: 2015

A set of saturated and dry-saturated large-scale triaxial tests were conducted in order to explore the effects of stress conditions on the saturation-induced collapse deformation behavior of a rockfill material. Specimens were tested in different confining pressures and for dry-saturated tests the specimens were submerged in various shear stress levels. The results indicate that in all of the dry-saturated tests a sudden reduction in the volume of the specimens was observed during the submerging process. The ratio of the minimum axial strength of a submerged specimen (at the end of the saturation process) to the shear strength of the specimen before saturation is defined as the coefficient of stress recovery, Csr. Results of the dry-saturated tests showed that this ratio increases as the confining pressure increases and decreases by increasing the shear stress level. According to the results of dry-saturated tests the values of internal friction angle reduction caused by saturation (Δϕc), the ratio of the elasticity modulus of the material after saturation to its elasticity modulus in dry condition, i.e., Ewet/Edry, and also the saturation induced sudden volumetric strain (εvc) decrease as the confining pressure increases. However the shear stress level does not have any meaningful effect on the variation of Dfc, Ewet/Edry and (εvc). © 2015, Korean Society of Civil Engineers and Springer-Verlag Berlin Heidelberg.


Tabibnejad A.,Iran University of Science and Technology | Heshmati A.,Iran University of Science and Technology | Salehzadeh H.,Iran University of Science and Technology | Tabatabaei S.H.,Housing & Urban Development Research Center
KSCE Journal of Civil Engineering | Year: 2015

Rockfill material, such as other coarse grained materials, undergoes rapid or sudden settlements of relatively large values, without any changes in the applied loads and only because of submerging. In the literature this phenomenon is called collapse deformation. The effects of gradation curve and dry density on the collapse deformation behavior of a rockfill material were explored and the changes in the strength and deformability parameters of this material caused by submerging were determined. Two large scale triaxial equipments with three different sample diameters of 20, 30 and 80 cm were employed and a set of dry-saturated tests were conducted. Specimens with different gradation curves and various initial dry densities were tested. The results indicate that in all of the dry-saturated tests, sudden reductions in the shear strengths and volumes of the specimens were observed during the submerging process. The effects of material maximum particle size, fines content and initial dry density on the value of sudden shear strength reduction, internal friction angle reduction caused by saturation (Δϕc), the change in elasticity modulus of the material due to submerging, i.e., (Ewet/Edry), and also the saturation-induced sudden volumetric strain (εvc) were evaluated and discussed. © 2015, Korean Society of Civil Engineers and Springer-Verlag Berlin Heidelberg.


Tadayon M.H.,University of Tehran | Shekarchi M.,University of Tehran | Shekarchi M.,Housing & Urban Development Research Center | Tadayon M.,Housing & Urban Development Research Center
Construction and Building Materials | Year: 2016

Chloride ingress in concrete is the most deteriorating factor for reinforced concrete structures exposed to marine environment. This phenomenon depassivates reinforcing steel in concrete and causes steel corrosion. To improve the durability and serviceability of concrete structures in harsh environments with high relative humidity, temperature and concentration of chloride ions such as in the Persian Gulf, the addition of silica fume and other pozzolans have been recommended by several investigations. In this paper, the chloride ion diffusivity and mechanical performance of concretes containing silica fume, metakaolin and natural zeolite, and those of concretes with different water-cement ratios (w/c) under in-situ tidal exposure condition were investigated. To achieve this objective, concrete specimens with w/c of 0.35, 0.40, 0.45 and 0.50 were fabricated. In addition, to examine the performance of pozzolans, other specimens with constant water-binder ratio (w/b) of 0.40 containing 5% silica fume, 5% metakaolin and 10% natural zeolite were prepared. All of the specimens were subjected to laboratory and tidal exposure in the field conditions. The results indicate that 10% natural zeolite, 5% metakaolin and 5% silica fume have similar effects on concrete strength and durability in harsh marine environments. In addition, it is concluded that at long time field exposure, chloride diffusion coefficient and surface chloride content of different mixtures reach to relatively similar amounts. © 2016 Elsevier Ltd

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