فهرست مطالب

Asian journal of civil engineering - Volume:17 Issue:8, 2016
  • Volume:17 Issue:8, 2016
  • تاریخ انتشار: 1395/06/16
  • تعداد عناوین: 10
|
  • A. Kada *, B. Lamri, L. Mesquita M.R., A. Bouchair Page 1035
    This work is intended to analyse the behaviour steel beams with apertures under high temperatures rise due to fire using finite elements simulations with ANSYS software. It includes a structural fire analysis and a comparative study of cellular and castellated steel beams which takes into account transient temperature effect, material and geometric non-linear behaviour. FE models which estimate limiting time, mid-span deflection and failure temperature are presented for hexagonal and circular types of web opening shapes under several uniform load levels. The study shows that for any beam with closely spaced openings failure in fire will in most cases be caused by failure of the steel web. The numbers of web-openings and cells as well as their shapes are critical for the behaviour of castellated sections and cellular beams under fire condition.
    Keywords: ISO834 fire, web, aperture, cellular beam, finite element modelling, time, deflection behaviour, ANSYS
  • K. Roy, A. Kumar Bairagi * Page 1055
    This paper presents the study on wind pressure, velocity and force coefficient analysis done in ANSYS software using CFD simulation (k-εmodel) for stepped unsymmetrical plan shape tall building for a wind incidence angle ranging from 0 ̊ to 360 ̊ with an interval of 45 ̊ in the ratio of 1:300. The study aims at establishing the similarity between the codes like IS 875-(PART 3)(1987), AS/NZS: 1170.2 (2011), ASCE: 7-02 (2002), and the experimental rectangular model. The flow patterns around the building are considered for different heights and for different wind angles which help to understand the difference in pressure variation for designing purpose of the building.
    Keywords: Computational fluid dynamics (CFD), stepped shape, wind angle, pressure coefficient, force coefficient, velocity profile
  • Ajmal Wahidi *, D. Rama Seshu Page 1077
    Buildings with floating column are highly undesirable to be built in seismically active areas since due to discontinuity in direct load path they have shown poor performance in the past earthquakes. This paper studies the nonlinear (pushover) analysis for G story normal and floating column buildings using the response spectrum specified in the IS code in SAP2000. Behaviour of building swith floating column identified and based on these findings some new system of floating column building swith different patterns of bracings and shear wall sare proposed to make the buildings with floating column safe in seismically active areas.
    Keywords: Buildings, floating column, braces, shear wall, pushover analysis
  • R. Hemaanitha *, S. Kothandaraman Page 1087
    The study explores the experimental results of strengthening RC beams attached with external truss. The truss was designed and fabricated with 42 × 42 × 6 mm angle sections for tie members and 2 pieces of 180 × 3.4mm flats for strut. Two different struts with aheight of 300mm and 400mm were used. The result indicates that the load carrying capacity of the retrofitted beams could be increased 2.5 times and 2.7 times respectively compared to the basic beam; the maximum crack width at the ultimate stage was in the range of 2 to 2.5mm when compared to the basic beam (4 to 5 mm). However, the method adopted in the study has got many advantages such as enhancing the load carrying capacity, controlling the crack width, economical and easy to install.
    Keywords: Retrofitting, external truss, flexural strengthening, deflection, crack width
  • Vaishnavi V. Battul, K. Muthumani * Page 1099
    Historically regular buildings perform better in earthquake than irregular buildings which are prone to damage during earthquake. But dueto functional and architectural requirements irregularity in structure is unavoidable. While trying to understand the seismic response of irregular structure many researches attempt by using nonlinear static pushover analysis. Performance point in pushover analysis may evaluate the capacity and demand of overall structure. But the response of individual member in the structure with reference to its capacity and the demand that exist in the member needs in depth study. This paper reports results of such study on three different structures. The members so identified are modified so that the structure not only satisfies performance point requirement but also at local level all the members have enough capacity that far exceeds the demand requirement.
    Keywords: Plan irregularity, pushover analysis, performance, irregularity level
  • M. Gerami, A.H. Mashayekhi *, N. Siahpolo Page 1111
    In this research using the DAP method, the higher modes effects under the far and near -fault earthquakes are investigated. For this purpose 5 intermediate (ductility) steel moment resisting frames with 4, 7, 10, 15, and 20 stories have been investigated. The results show that in all the structures being investigated, the higher modes effects under the far fault earthquakes are greater with respect to the near- fault earthquakes. Also, by increase in the structure's height, the effects of higher modes increase. The base shear resulting from the near- fault earthquakes, considering the higher modes effects, has the negligible difference with the base shear resulting from the first mode of the structures.
    Keywords: Higher mode effect, pushover methods, near, fault earthquakes, forward directivity effect, dap method
  • M. Beena Mol*, S. Prabavathy, J. Mohanalin Page 1131
    Accelerograms are the random time series representation of the strong ground motions called earthquake. Processing of accelerograms is done before using them for any seismic and engineering applications. This article focuses the impact of threshold and noise in wavelet processing using experiments on random generated time series signals. Experiments conducted on the global thresholds currently in use lead us to propose a novel fuzzy based threshold to remove the random noise. Therefore a fuzzy based threshold determination in the domain of wavelet coefficients has been proposed and effectively used in denoising the real observed accelerograms. Also, the experimental results on synthetic signals has outperformed the existing universal and sure thresholds in terms of SNR of 20.3 and RMSE of 0.0019, respectively.
    Keywords: Accelerograms, earthquake, fuzzy, de, noising, wavelet transforms
  • P. Gajalakshmi *, K. Sriram, U. Elakeya Page 1151
    Beam column joint is an important component of a reinforced concrete moment resisting frame and it should be designed and detailed properly, especially when the frame is subjected to earthquake loading. Failure of beam - column joints during earthquake is governed by bond and shear failure mechanism, which are brittle in nature. Therefore, it is necessary to study the behavior of reinforced concrete joints under earthquake loading. Here an attempt is made to observe the difference in the behavior of beam – column joint designed using IS 13920 – 1993 and IS 456 – 2000 which is studied under simulated seismic loading and also the behavior of the joint is studied when it is wrapped with FRP. Fiber reinforced concrete is used to improve the ductility of the member.
    Keywords: Beam, column joint, ductility, fibre reinforced polymer, fibre reinforced concrete, FRP wrapping
  • G.R. Aravind, C. Arunkumar* Page 1167
    The aim of this research work is to study the flexural behaviour of steel beam-column connection with gusset plate under static loading condition. Connections are normally the focal points of receiving damage due to overload including earthquake. The main reason for the failure of connection is, their inability to deliver large rotation. Gusset plates are used for connecting two or more members together. While gusset plates are used as the connecting element of bracing to the beam-column joint, the load carrying capacity and stiffness of beam-column joints are possible to increase. To know the increasing capacity of beamcolumn connection with gusset plate are determined by conducting the experimental and analytical program. An experimental research demonstrates the actual behaviour of steel beam-column connection with gusset plate. There are four number of specimens are tested under static loading condition. Each specimen is fabricated by changing the connection parameter like gusset plate thickness, angle leg length. Finite element analysis was done using ABAQUS. Using the finite element model, a parametric study was conducted to determine the changes in the connection and initiation of damages. The contact element which is used as a surface to surface instead of node to node. Accurate results can be obtained by validating the results of experimental work with FEM analysis. The comparison is made for the deflection and strain occurred on the experimental program with the analytical results.
    Keywords: Gusset plate, beam, column joint, stiffness, flexural behaviour
  • P. Zakian, N. Khaji * Page 1189
    This article employs higher order spectral finite elements to model seismic wave propagation and fault dislocation phenomena in two dimensional elastic media. This study presents two main phases comprising wave propagation and fault dislocation, respectively. In the first phase, accuracy and dispersion assessments are performed to indicate capability of these elements in such problems, revealing suitable polynomial orders which should be utilized for obtaining better accuracy of wave propagation. In the second phase, the split node technique is developed in terms of spectral finite element method in order to simulate both static and dynamic fault dislocations. The split node technique was originally presented for static dislocation using finite element method, whereas it is herein developed to both static and dynamic dislocations using spectral finite element method. Also, the dislocations are modeled in layered half space to incorporate more realistic analyses. Several numerical simulations are provided to demonstrate accuracy and ability of spectral finite elements for modeling of wave propagation and fault dynamics.
    Keywords: Wave propagation, fault dislocation, spectral finite element method (SFEM), split node technique (SNT), layered half space, accuracy assessment