فهرست مطالب

Asian journal of civil engineering - Volume:18 Issue:4, 2017
  • Volume:18 Issue:4, 2017
  • تاریخ انتشار: 1395/10/27
  • تعداد عناوین: 10
|
  • S. Das *, S. Choudhury, A.K. Dey Page 535
    Low-rise reinforced concrete (RC) buildings are common as dwelling houses in developing nations including the Indian subcontinent. Passive damper in the form of TLDs appear to be promising in seismic mitigation of such buildings. Apart from this, in day-to-day building design, the presence of masonry infill is generally ignored, except its mass. In the present study 1/4th scale 3-storey RC model building has been considered with and without infill panels for investigating the effectiveness of TLDs in vibration mitigation.
    A series of experimental tests has been carried out using a unidirectional shaking table under horizontal strong harmonic excitation. In the first phase the response mitigation on bare frame building model in with TLDs has been studied. In the second phase, building with infill panel has been tested incorporating TLDs. The present study shows that substantial response reduction is possible in low-rise RC buildings using TLDs as passive dampers.
    Keywords: tuned liquid dampers, response reduction, infill frame, mass ratio, low, rise buildings
  • R. Aghayari *, M. Ashrafy, M. Tahamouli Roudsari Page 547
    RC coupled shear walls are known as one of the best and popular lateral load resisting structural systems. Most of the structural design codes have no seismic design considerations for base shear and fundamental vibration period. In current study finite element models were generated to provide a reliable data base to estimate the base shear and fundamental period. The differences between the behavior of in-plane and out-of-plane actions in these systems were investigated. In the final stage corrective coefficients will present according to analyses results. More accurate estimation of the demand makes more resistant structures against wind and earthquake loads.
    Keywords: RC coupled shear wall, base shear, fundamental vibrational period, non, linear finite element analysis
  • S.J. Jung *, Ahmad M. Abu Abdo Page 567
    A Finite Element Analysis has been applied to a type of four-point bending specimen with S/W=3 to determine which condition a pure mode II can be constructed. The ANSYS simulation results have demonstrated that conditions l1 = l4 and l2 = l3 could not guarantee a pure mode II case be generated. The ratio W/D and ratio a/W have a remarkable contribution to the formation of pure mode II. At W/D = 3.75 and a/W from 0.25 to 0.35, an almost perfect shear mode II can be achieved at the single crack tip region. When a/W varies 0.2 to 0.6, the specimen can also be treated as in pure shear mode II case if a 6 percent of the ratio KI/KII is acceptable. A KII expression in fifth-degree polynomials has been calibrated.
    Keywords: Fracture mechanics, four, point bending, stress intensity factor, mode II fracture, finite element analysis
  • A. Hosseinmardi, M. Heristchian * Page 577
    This paper studies the increase in strength and stiffness of the composite double-layer grids, whose top-layers combine the steel frame elements with concrete decks. Firstly, the paper obtains the ultimate load capacities of square concrete decks with and without ribbed edges under various support and load conditions. Then, the load capacity of a composite doublelayer grid is obtained under various loads, geometric and support conditions. A comparison of the results indicates that: the composite grid exhibits 2 to 5 times higher load capacity than the corresponding non-composite grid. In addition, a composite grid with (roller ꘩) supports has about 20% of the load capacity of the identical grid with (pin ꘩) supports.
    Keywords: Concrete decks, double, layer grids, ultimate strength, stiffness, composite spatial structures, numerical modelling
  • S.B. Singh *, A. Chauhan, P. Munjal Page 593
    The present study deals with the numerically predicted response of a masonry wall strengthened in flexure using glass fiber reinforced polymer (GFRP) longitudinal strips and subjected to equivalent blast static loading. Threat levels to the blast loading in terms of support rotation of the wall are compared with the experimental results available in literature. A parametric study has been carried out to examine the effect of thickness, width, strength of FRP strips, and different laminates, i.e., cross-ply, angle-ply and quasi-isotropic on the response of the masonry wall. Moreover, the effect of the slenderness ratio, i.e., L/d and aspect ratio i.e., L/B of the wall are also considered in the parametric study. It is observed that equivalent static loading could be used for masonry wall subjected to blast loading to predict the threat level under blast situation.
    Keywords: Equivalent blast static loading, Fiber reinforced polymer, Masonry walls, Numerical modelling
  • A. Chikhi *, M. Djermane Page 607
    The behavior of storage tanks'' analysis in seismic areas is of major importance because of the strategic nature of these works. The steel cylindrical tanks are the most susceptible to damage due to dynamic buckling during earthquakes. In this study, three criteria are used to estimate the critical peak ground acceleration caused the tank instability. The liquid inside the tank was modeled using specific Ansys''s finite elements and fluid-structure interaction. The calculation includes modal and time history analysis, including material and geometric non-linearity. The result values are compared with standard code previsions as well as the results of previous numerical research, and show the need to improve code provisions.
    Keywords: Dynamic buckling, tanks, earthquakes, finite element, fluid, structure interaction, instability criteria
  • S. Annamalai, S. Thirugnanasambandam, K. Muthumani * Page 621
    Portland cement is widely used all over the world and the consumption is next to the consumption of water. The manufacturing of Portland cement emits large quantity of CO2 which causes pollution to the environment and makes serious impact on global warming. To reduce the emission of CO2 by way of replacing the cement concrete, an alternative concrete called Geopolymer Concrete (GPC) was introduced in the year 1980. GPC is a new class of concrete based on an inorganic alumino – silicate binder system compared to the hydrated calcium silicate binder system of Portland cement concrete. To produce the Geopolymer Concrete (GPC) an alkali – activator solution called alkaline liquid consists of sodium hydroxide (NaOH) and sodium silicate (Na2Sio3) is used as a catalyst to extract the silicon (Si) and Aluminium (Al) from the source material of Ground Granulated Blast Furnace Slag (GGBS) and Fly Ash (FA) which produce a binder like gel by polymerization which is similar to the gel of Portland cement concrete by hydration. NaOH in pellet form was dissolved in potable water and mixed with Na2 Sio3 in liquid form to prepare the alkaline solution. Four beams of M 60 grade of size 125 x 250 x 3200 mm were cast and tested for flexure. Out of these four beams, two beams are control beams with Portland cement concrete and the remaining two are GPC beams. The GPC beams were ambient cured and the control beams by water curing. Under reinforced sections were designed for both GPC and control beams. Cubes were cast to find out the compressive strength. The flexural behavior for all the four beams was compared. Flexural strength and compressive strength were found out.
    Keywords: Geopolymer concrete (GPC) alkaline liquid, polymerization, ambient cured, catalyst
  • P.P. Debnath *, S. Choudhury Page 633
    Frame - shear wall buildings are common for high rise multi-storied RC buildings. When these walls are situated in advantageous positions in a building, they perform as an efficient lateral-force resisting system, and also fulfilling other functional requirements. In conventional analysis, shear wall is modeled as wide column, which does not always provide the realistic behavior of a shear wall. In this present work, buildings have been modeled and designed, and a detailed analysis is carried out on structural walls. The building frame and length of shear wall design has been carried out by Unified Performance Based Design (UPBD) with takes both elastic and plastic rotation into consideration along with performance level. In this study shear walls are modeled as multi layered shell element which is an advanced addition in SAP2000 software. A few challenges in interpreting the performances of shear wall as per UPBD method were faced while using shell element. Non-linear analysis with shell element is carried out and attempts to interpret its performance in terms of stresses in different layers and hinge rotation have been carried out.
    Keywords: Performance based design, unified performance based design, multi, layered shell element, performance level, plastic rotation, shear wall
  • M. Anbarasu * Page 643
    This work aims at investigating the buckling behaviour of cold-formed steel (CFS) lipped channel (LC) beams undergoing local(L)-distortional(D)-lateral-torsional (LT) buckling mode interaction for the sake of developing an analytical model to calculate the ultimate resistance to bending moment. The section geometries are identified to have nearly equal elastic local, distortional and lateral-torsional buckling moment values by performing elastic buckling analysis. The identified sections satisfy the condition for prequalified sections in AISI-S100-2007. A finite-element model has been developed and verified against the available test data for cold-formed steel lipped channel sections subjected to the major axis bending. Parametric studies were carried out to investigate the influence of geometries and yield stress values. The numerical results are compared with design predictions from the Direct Strength Method (DSM) in North American specifications for cold-formed steel structures. Based on the comparisons, design recommendations are introduced for coldformed steel lipped channel beams which experiencing local/distortional/lateral-torsional buckling mode interaction.
    Keywords: Buckling interaction, distortional buckling, local buckling, lateral, torsional buckling, lipped channel beam, local, distortional, lateral, torsional buckling interaction
  • A. Kaveh *, D. Jafarpour Laien Page 657
    In this study optimal design of reinforced concrete cantilever retaining walls is performed under static and earthquake loading conditions utilizing the Colliding Bodies of Optimization (CBO), Enhanced Colliding Bodies of Optimization (ECBO) and vibrating particles system (VPS) methods. This design is based on ACI 318-05 and two theories known as Coulomb and Rankine have been applied for estimating the earth pressures under static loading condition, and Mononobe-Okabe method have been applied for estimating earth pressures under earthquake loading condition. The objective function considered is the cost of the retaining wall and this function is minimized subjected to design constraints. The performances of the CBO, ECBO and VPS and some other optimization algorithms are compared for the considered benchmark examples.
    Keywords: Reinforced concrete, cantilever retaining wall, colliding bodies optimization, enhanced colliding bodies optimization, vibrating particles system optimization