Indian Institute of Technology Palakkad&nbsp;(IIT Palakkad or IIT PKD) is a public autonomous&nbsp;engineering&nbsp;and&nbsp;research&nbsp;institute located in&nbsp;Palakkad,&nbsp;Kerala. It was&nbsp;one of the five new&nbsp;IITs&nbsp;proposed in the&nbsp;2014 Union budget of India. The campus was inaugurated on 3 August 2015. The institute has 94 faculty, 978 students, and 63 non-teaching staffs.

IT Palakkad currently offers four-year Bachelor of Technology (B.Tech) and two years MS programmes in 8 different engineering disciplines including&nbsp;Computer Science, Electrical, Mechanical, Civil among others.

&nbsp;

IIT Palakkad

World University root node

Department of Civil Engineering

Analysis and Design of Plated Structures

Behavior, analysis and design of light gauge steel members

The effective width method (EWM) for calculating the ultimate strength of cold-formed steel (CFS) members assumes simply supported boundary conditions along the plate edges. Unstiffened plates, simply supported along three edges and unsupported along one longitudinal edge buckle in a single half-wave equal to plate length when subjected to uniform compression. It has been observed from the finite element analysis results that the simply supported unstiffened plates with large length to width ratios (L/ b≥ 10) the deformation pattern changes from a single half-wave to a combination of three half-waves corresponding to the ultimate load. One of the possible reasons for this is the nearly same elastic buckling stresses in the first few modes leading to the interaction of higher buckling modes. At larger L/b ratios the interaction of the third buckling mode with fundamental mode was observed causing the reduction in the ultimate strength. A similar reduction in the ultimate strength due to buckling mode interactions are also found in CFS plain equal angle sections, as such sections composed of only unstiffened plates which buckle simultaneously. In sections like plain channels, where additional rotational restraint along the supported longitudinal edge is present, such mode interactions are found to not influence the strength of unstiffened elements in sections. © 2021, The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

Lecture Notes in Civil Engineering

Interaction of Higher Buckling Modes in Uniformly Compressed Simply Supported Unstiffened Plates

The strength of thin-walled cold formed steel (CFS) lipped channel compression members may be governed by yielding, local, distortional, or global buckling or any possible interaction among these buckling modes. The interaction between buckling modes reduces the strength of thin-walled members to values below its strengths as affected by any one of the independent buckling modes. The direct strength method (DSM), which significantly simplified the evaluation of design strength of CFS members, recognizes this reduction in strength caused by interaction of buckling modes, but explicitly handles local-global interaction only. A simple and accurate interaction equation that accounts for interaction between all possible buckling failure modes for CFS lipped channel compression members is proposed in this paper. The method requires the use of modified DSM equations for evaluating the strength under the different independent buckling modes (local and distortional). The proposed interaction equation is validated with both experimental as well as numerical results.

Interaction of local, distortional and overall buckling in cold formed steel lipped channel compression members

The direct strength method (DSM) simplified the design of cold-formed steel (CFS) beams and columns compared with the traditional effective width method (EWM). In this paper, DSM equations for the distortional buckling (DB) strength are evaluated using the results of the experimental study on channel compression members with edge and intermediate stiffeners as well as nonlinear finite-element analysis (FEA) of the stiffened lipped channel compression members with various configurations, which fail after only DB. A total of 14 fixed-ended stiffened lipped channel compression members with intermediate stiffeners in both the web and flanges were tested, which failed after only DB. Further, additional data on the DB behavior is generated based on a parametric study using the nonlinear FEA, which was initially calibrated with the test data. A study on effect of parameters, such as the type of cross section, the dimensions of the cross section, the lip depth to flange width ratio (d/b), the web height to the flange width ratio (h/b), the yield stress (fy), end boundary condition (EBC) and the failure modes, shows that the nondimensional ultimate strength, expressed as the ratio of the ultimate strength to yield strength under compression, Pu/Py, is adequately addressed through the nondimensional DB slenderness, $\lambda$d, alone as assumed in the DSM. The test and the analysis results show that the DSM equations generally evaluate the strength of stiffened lipped channel members under DB conservatively. Modifications to the DSM equations are suggested to evaluate the DB strength of stiffened lipped channel members more accurately.

Journal of Structural Engineering

Distortional Buckling of CFS Stiffened Lipped Channel Compression Members

The compressive strength of cold-formed steel (CFS) lipped channel (LC) members may be governed by yielding, local, distortional, or overall buckling and any possible interaction among these modes. The direct strength method (DSM) has been advanced recently for evaluating the strength of CFS LC beams and columns. Although the DSM is an improvement over other methods in terms of simplicity and accuracy, further improvement by minor modification to the DSM is possible if all the parameters that affect the strength of such members is properly accounted for and understood. In this study, the DSM equations for evaluating the strength of members that fail after experiencing only local buckling are discussed. The strength of such members, according to the DSM, is a function of only the ratio of yield strength of the section (Py) to the elastic local buckling load (Pcrℓ) (also equal to the reciprocal of square of the nondimensional local buckling slenderness ratio, 1/$\lambda$ℓ2). This study indicates that the relative area of the stocky elements of the cross section, which are less vulnerable to elastic local buckling, also influences the strength of such members. Using the experimental results available in the literature and the finite-element analysis data generated in this study, the behavior and strength of stub LC compression members experiencing only local buckling before failure by yielding are evaluated. Simple modifications to the currently available DSM equations are suggested to more accurately evaluate the strength of such members. {\textcopyright} 2012 American Society of Civil Engineers.

Design Strength of Locally Buckling Stub-Lipped Channel Columns

The axial compressive strength of the cold-formed steel (CFS) members with edge or intermediate stiffener is affected by interaction of local, distortional and overall buckling. In order to overcome the tedious and time consuming nature of the traditional Effective Section method of evaluating strength of such members, direct strength method (DSM) has been advanced recently. However, the DSM has not been adequately evaluated for calculating the strength of compression members (such as tubular, plain channel and I-sections) consisting of only stiffened and unstiffened elements, without either lip stiffener or intermediate stiffener. These members experience interaction of only local and overall buckling before failure. In this paper, results of a study on the suitability of DSM to evaluate the compressive strength of plain channel, I and rectangular tubular members is presented. Extensive experimental data in literature and additional data generated using currently accepted effective width method (based on better estimate of local buckling stress evaluated considering element interaction), are used in this study. It is found that DSM can be used to evaluate strength of such members also. {\textcopyright} 2010 ASCE.