فهرست مطالب

Asian journal of civil engineering - Volume:18 Issue:3, 2016
  • Volume:18 Issue:3, 2016
  • تاریخ انتشار: 1395/07/19
  • تعداد عناوین: 11
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  • A. Kaveh*, V.R. Mahdavi Page 335
    The main aim of this paper is to present a new single-solution metaheuristic algorithm so-called global sensitivity analysis based (GSAB) algorithm for discrete sizing optimization of steel frames. In the GSAB method, the single solution moves towards specified regions determined using the sensitivity indicator of the variables. In comparison to population-based meta-heuristic algorithms, where all the variables are simultaneously changed in the optimization process, in this approach first the highly sensitive variables of solution and then the less sensitive ones are iteratively changed in the search space, therefore the global convergence of algorithm is accelerated. In order to evaluate the performance of the GSAB algorithm, three planar frame benchmark problems are conducted. The experimental results show that the proposed method performs better than, or at least as well as other population-based meta-heuristic algorithms, especially in decreasing the number of fitness function evaluation.
    Keywords: Optimal design, steel frame structures, global sensitivity analysis, meta, heuristic, sensitivity indicator
  • G.N. Prajapati*, A.D. Pandey, Aalok, T.B. Reddy Page 357
    The fiber reinforced polymer (FRP) sheets known for their high strength and stiffness predominantly used in retrofitting and strengthening of reinforced concrete (RC) structural member. In this paper, RC beams reinforced externally with different type of FRP sheets (BFRP, CFRP and GFRP) using U-wraps in shear zone modelled analytically using finite element software to check the reliability by comparing the results obtained from finite element analysis with the experimental results from past studies. The comparisons are made for load deflection plot, crack pattern at failure and failure loads. The finite element analysis yields results which show a good agreement with observations and data from experimental testing.
    Keywords: RC beam, retrofitting, FRP, shear strengthening, FEM, ANSYS
  • M. Grigorian* (Ms) Moghadasi Page 371
    The paper introduces a new earthquake resistant rocking-wall moment frame (RWMF) that is capable of damage reduction, collapse avoidance and self-centering due to strong ground motion. The system consists of a grade beam restrained moment frame, (GBRMF) attached to a co-planar, post tensioned (PT) rigid rocking core (RRC) by means of gap opening link beams (GOLBs) and buckling restrained braces (BRBs). Several practical details aiming at damage reduction have been presented. Worked examples have also been provided to demonstrate the validity of the proposed solutions. All results have been verified by independent computer analysis. The proposed formulae are ideally suited for preliminary design and teaching purposes.
    Keywords: Rocking, wall, moment frame, initial imperfections, collapse prevention, self, centering, reparability
  • G. Salaiamuthavalli, C.D.R. Balaji* Page 399
    This paper presents the analytical study on non-linear behavior of FRP-concrete-steel double skin tubular (DST) columns subjected to impact loading. To improve the strength and ductility of columns, carbon fibre reinforced polymer (CFRP) is used. Extended finite element analysis is carried out on a total of twelve column specimens including nine FRP-concrete-steel double skin tubular (DST) specimens and three reinforced concrete (RC) specimens with inner hollow tube with varying parameters of FRP layers and impact energy. Finite element analysis of these models was conducted using ABAQUS/CAE software. Predicted maximum deflection and peak acceleration of all the specimens from the analysis were validated with the experimental results available in literature. The results of finite element simulations show good agreement with the experimental results.
    Keywords: Double skin tubular column, carbon fiber, reinforced polymer, impact loading, finite element analysis
  • E.M.B. Boudjellal*, A.Kadid Page 411
    In this paper six tank models, three cylindrical and three rectangular with the same liquid capacity but with different slimness: tall, medium and shallow are numerically simulated using FEM in order to investigate their seismic behavior under three seismic components of four distinct ground motions with different frequency parameters. The results showed the important effect of vertical component of earthquakes on the response of rectangular tanks especially when its frequency content in the same range as that of the tank, while the cylindrical tanks were less affected by the vertical component and of the frequency content of the records.
    Keywords: Rectangular, cylindrical tanks, fluid, structure interaction, vertical component, frequency content
  • T. Mahdi* Page 433
    Arches, vaults and domes are common features in the cultures of old civilizations. They were usually made of sun-dried bricks, fired bricks or stones with different types of mortar. The majority of these components are vulnerable to seismic effects. To present a viable study on their seismic vulnerability, all the factors influencing their behavior need to be investigated. In this paper, the construction materials used and the structural features of these elements are briefly described. Furthermore, the different aspects of using numerical methods for analyzing these elements are discussed. Finally, measures needed to improve their resistance are suggested.
    Keywords: Masonry, arch, vault, dome, seismic vulnerability, soil movement
  • M.I. Khodakarami*, M. Maleki, M. Mounesi, Sorkheh Page 451
    A novel instrument named inverse structural airfoil (ISA) is proposed in order to improve the performance of buildings against wind loads, which reduces wind-induced responses of mid to high-rise buildings. This tool can use for a new structures which are designing for wind load as well as one can use it for rehabilitation of existing buildings. An inverse airfoil is implemented, and so its lift-up force applies in the negative direction and works as lift-down force and this is useful for improvement of structures performance under wind loads and the detrimental effects of wind transfer to helpful effects. In this paper, the procedure that ISA works is explained, and then efficiency of ISA is investigated by using various types of ISA buildings in three wind zones with different wind velocity. Results show when ISA is employed in a structure system, the response of the structures against wind have been improved without any changes in the building configuration and the overall and inter-story drift, uplift forces at foundations, overturning moment of structures are reduced; on the other hand, with this tools, wind will be an effective and positive parameter in order to overcome detrimental effects of itself on the buildings.
    Keywords: Inverse structural airfoil, wind loads, uplift, structural stability, lateral drift
  • B. Ghanbari*, A.H. Akhaveissy Page 473
    The evaluation of residual displacement of structures is a critical problem because it has important role in the Definition of post-earthquake performance level of structures. In this paper, the mean residual displacement ratios (RDRs) (residual displacement normalized by maximum inelastic displacement) are computed for constant ductility of single-degree-of-freedom (SDOF) systems subjected to 116 strong ground motion records from severe earthquakes events in Iran. A total number of 25,056 nonlinear response history analyses (RHAs) were performed to accurately evaluate RDRs. The influence of frequency content and significant duration of ground motions on mean RDRs are evaluated and discussed statistically. The results indicated that the validity of influence of these ground motion parameters on mean RDRs is dependently of the post yield stiffness ratio and the influence of these parameters becomes more obvious for SDOF systems with post-yield stiffness greater than zero. The obtaining data from RHAs results were used for the development of new mean RDRs equation. It has been found that the proposed equation can predict mean RDRs with adequate accuracy.
    Keywords: Residual displacement, frequency content, significant duration
  • J. Karthick*, K. Suguna, P.N. Raghunath Page 485
    This paper presents the structural behavior of reinforced concrete beams with surface mounted GFRP and hybrid FRP laminates under static loading condition. A total of seven beams were cast and tested under four-point bending. One beam without FRP served as the control beam, two beams were strengthened using glass fibre reinforced polymer laminates (GFRP) and four beams were strengthened using hybrid FRP (carbon glass) laminates in flexure. From the experimental study, it was observed that strengthening of RC beams with hybrid FRP laminates resulted in increased load carrying capacity, reduced deformations, enhanced ductility and energy absorption. The load carrying capacity of the test beams was predicted using ACI 440.2R-08 guidelines. The experimental and predicted results are in good agreement.
    Keywords: Beams, composites, ductility, GFRP: hybrid FRP, strengthening
  • G.C. Behera* Page 497
    Wrapping technology is one of the effective ways of strengthening concrete elements. Several researchers reported the effectiveness of Glass fiber reinforced polymers and carbon fiber reinforced polymers for improving the strength of the concrete elements. Wrapping on three sides is one of the effective methods for strengthening the beams supporting slabs. Very less literature is available on the strength enhancement of “U” wrapped concrete elements subjected to torsional loads. In this investigation an attempt is made to quantify the improvement in twist of “U” wrapped rectangular concrete members subjected to torsional loads “U” wraps. Carbon fiber has taken the driver‟s seat as a wrapping material in developed countries. From cost effective point of view ferrocement can be used as a wrapping material in place of FRP. Beams were cast with different number of mesh layers, different torsional reinforcement, different grades of concrete and mortar. The beams were analyzed with MARS. Analytical model was developed to predict secant stiffness at cracking torque. The predictions for twist at cracking torque are in good agreement with experimental test results.
    Keywords: Ferrocement, U wrap, twist at cracking torque, MARS, analytical model
  • D. Sen, M. Begum* Page 515
    Retrofitting is required for the structures which undergone strength deterioration by seismic events or have to sustain additional applied loads. Steel angles and strips jacketing is a quick and effective method to restore the strength of columns. Several researchers addressed the effectiveness of this jacketing method on columns through experimental works. Some researchers intended to pave the way of design procedure of strengthened RC columns by formulating compressive capacity prediction models. This study primarily intends to review the experimental works and analytical models available in the literature. Finally, a comparative study has been conducted considering available parameters in literature to identify the key parameters, which have influences in a large extent on the compressive strength of steel angles and strips strengthened RC columns.
    Keywords: Strengthening, steel angle, strip, confinement, RC column, jacket