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N. Subramanian

Bio: N. Subramanian is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Barrel vault & Braced frame. The author has an hindex of 2, co-authored 5 publications receiving 6 citations.

Papers
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Journal ArticleDOI
TL;DR: In this paper, the displacement method of structural analysis is used with an iterative procedure to take into account the secondary effects of offset prismatic members and the complete stiffness matrix has been derived.
Abstract: The problems involved in the analysis of three dimensional frames having offset prismatic members are investigated. The sources of offset considered are the rigid gusset plate effects and misalignment of members from specified joint positions. The secondary effects due to axial forces are also considered in the analysis. The displacement method of structural analysis is used with an iterative procedure to take into account the secondary effects. The complete stiffness matrix has been derived. The computer program developed, based on this analysis, is also explained. From the example of steel frame folded plate it is seen that the difference in maximum axial forces and bending moments due to the offset members are about 20%. It appears that the method, developed herein, for analysing space frames having offset members, offers a very direct and versatile approach to the problem of analysing structures having misaligned members.

2 citations

Journal ArticleDOI
TL;DR: In this article, a computer analysis of steel braced barrel vaults is presented and compared with the approximate method of analysis suggested by Baer, and the drawbacks of Baer's method are discussed.
Abstract: The computer analysis of steel braced barrel vaults is presented. This analysis is compared with the approximate method of analysis suggested by Baer. The drawbacks of Baer's method are discussed. The behaviour of these frames due to the effect of laterals, edge trusses and different types of bracing systems is predicted. Based on this parametric study an economic system of braced barrel vault is suggested for practical applications.

2 citations

Journal ArticleDOI
TL;DR: In this paper, it was found that for efficient layout the laterals and edge trusses need to be provided only in the edge bays, while practical considerations like lack offit and settlement of supports do not adversely affect the stresses in most of the members.
Abstract: The behaviour of single bay steel frame folded plate roofs is fairly well understood[4]. In actual practice, multibay frames are mostly used to cover large column-free areas and as the behaviour of these is not well known an attempt has been made to predict their behaviour taking into account the action of laterals, edge trusses, lack of fit, support conditions and buckling. From this study, it is found that for efficient layout the laterals and edge trusses need to be provided only in the edge bays. Practical considerations like lack offit and settlement of supports do not adversely affect the stresses in most of the members.

2 citations

Journal ArticleDOI
TL;DR: In this paper, the behaviour of steel frame folded plate roofs was studied by analysing a number of frames and a standard module, which is amenable to prefabrication, was evolved.
Abstract: Steel frame folded plate roofs offer the possibility of providing large column free areas, and they have an interesting appearance. The only available method for the appropriate design of these frames is the Baer method. This method has many shortcomings and cannot be used in all circumstances. Hence the behaviour of steel frame folded plate roofs was studied by the authors by analysing a number of frames. Based on this study a standard module, which is amenable to prefabrication, was evolved. Design charts have been prepared for this module, and are presented in this paper. Using these charts two examples have been worked out and compared with the computer results. The charts can be used in design offices for the preliminary design of steel frame folded plate roofs without the use of rigorous computer methods.

Cited by
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Journal ArticleDOI
TL;DR: In this paper, the elastic and inelastic seismic behavior of single layer steel cylindrical lattice shells is examined through a parametric assessment, which also leads to proposed expressions for estimating the fundamental period and mode of vibration.
Abstract: This paper examines the elastic and inelastic seismic behaviour of single layer steel cylindrical lattice shells. The main dynamic characteristics for this form of structure are firstly examined through a parametric assessment, which also leads to proposed expressions for estimating the fundamental period and mode of vibration. The seismic response of five typical shell configurations, representing a wide range of rise to span ratios, is then assessed within the linear elastic range under selected earthquake excitations. Particular focus is given to the relative influence of the horizontal and vertical seismic components on the internal actions. In order to provide a means for evaluating the underlying inelastic behaviour, a simple pushover approach, which is suitable for this structural form, is suggested using the forces obtained from the fundamental mode shape. The peak angle change is proposed as a damage parameter within the nonlinear analysis for characterising the inelastic global and local demands in shells of different geometries. Incremental dynamic analysis is subsequently carried out in order to evaluate the detailed nonlinear time history response. The results provide detailed insights into the influence of the horizontal and vertical excitations on the nonlinear seismic response, and illustrate the suitability of the peak angle change as an inelastic deformation measure for shells of different geometric configurations. The main findings from the linear and nonlinear assessments are highlighted within the discussions, with a view to providing guidance for performance based assessment procedures as well as simplified design approaches.

11 citations

Journal ArticleDOI
TL;DR: The assessments presented in this paper can also be used to support detailed performance based guidelines as well as for informing geometry and size optimisation strategies.
Abstract: This paper examines the main considerations related to the seismic design and assessment of single layer steel cylindrical lattice shells, and offers recommendations for their practical application. Geometric configurations covering a wide range of rise to span ratios are considered within the investigation. An insight into the relative influence of seismic loading on shell design, in comparison to gravity conditions, is firstly provided through the use of digital parametric engineering procedures. This is followed by linear elastic response assessments which are used to propose a simplified procedure for estimating the internal seismic forces for the purpose of member sizing in early design stages. Suitable approaches for pushover analysis are then discussed and used to identify inherent plastic mechanisms. The results of incremental nonlinear dynamic analysis, using a suite of fourteen records, are also employed in order to validate the findings and to further assess the ultimate response under realistic seismic loading conditions. Based on the findings, representative ranges for behaviour factors and displacement modification coefficients are derived alongside discussions on their implementation within codified seismic design procedures. Apart from providing recommendations for simplified design approaches, the assessments presented in this paper can also be used to support detailed performance based guidelines as well as for informing geometry and size optimisation strategies.

6 citations

Journal ArticleDOI
TL;DR: In this paper, it was found that for efficient layout the laterals and edge trusses need to be provided only in the edge bays, while practical considerations like lack offit and settlement of supports do not adversely affect the stresses in most of the members.
Abstract: The behaviour of single bay steel frame folded plate roofs is fairly well understood[4]. In actual practice, multibay frames are mostly used to cover large column-free areas and as the behaviour of these is not well known an attempt has been made to predict their behaviour taking into account the action of laterals, edge trusses, lack of fit, support conditions and buckling. From this study, it is found that for efficient layout the laterals and edge trusses need to be provided only in the edge bays. Practical considerations like lack offit and settlement of supports do not adversely affect the stresses in most of the members.

2 citations

Journal ArticleDOI
TL;DR: In this article , the authors studied the steel pipe cutting and support stage in the pipe-roof pre-construction method (PPM) in Shenyang Metro construction case, and the measured data are consistent with the numerical simulation results.
Abstract: The studies on the steel pipe cutting and support stage in the pipe-roof pre-construction method (PPM) are rare, and their design lacks relevant standards, which is relatively conservative. Based on the Xinleyizhi Station of the Shenyang Metro construction case, MIDAS/GTS is used to study the stress of the original jacking steel pipes, supporting column, and surface subsidence under the influence of different construction parameters in the steel pipe cutting and support process in the PPM. The measured data are consistent with the numerical simulation results, which verifies the reliability of the numerical simulation results. With the increase of the distance between support columns, the maximum Mises stress of the original jacking steel pipe, the axial force of the support column, and the ground settlement gradually increase in a specific range. This indicates that the original design scheme can be optimized.

1 citations

01 Jan 2015
TL;DR: In this article, the authors investigate how different ways of modeling these connections affects the optimization of the final model and the extent to which the modification of the position of the eccentricities influences the optimization.
Abstract: Every year Seville’s city Council orders the construction of a giant gateway for the celebration of the April Fair. These constructions, whose dimensions are approximately 50 meters length, 40 meters height and variable depth of 4 to 5 meters, are spatial modular structures composed of steel tubular elements connected by clamps and covered by wood boards. The consideration or not of the eccentricities introduced by the connection element as well as the determination of the stiffness to consider is one of the major problems when developing the analysis model. The construction company aims to achieve their optimization in order to reduce the final cost. This paper investigates about how different ways of modeling these connections affects the optimization of the final model. The extent to which the modification of the position of the eccentricities influences the optimization is also discussed, as this aspect is difficult to control on site.

1 citations