Department of Civil Engineering

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.

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IIT Palakkad

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.

World University root node

Journal of Structural Engineering

Design Strength of Locally Buckling Stub-Lipped Channel Columns

Various base isolation schemes have been implemented to isolate a structure from intense base excitations. In this paper, performance of a friction sliding bearing with nonlinear restoring mechanism is studied on a three-storey steel moment-resisting frame building under varying seismic hazard conditions. The performance of the proposed system is compared with that of the fixed-base and with only the friction sliding bearing. For this purpose, the effectiveness of the proposed isolation system is evaluated in terms of the residual displacement, peak inter-storey drift and the maximum base displacement. It is envisioned that a system as proposed here, if optimized for a target hazard situation, will result in a cost-effective solution. © 2012 Springer-Verlag.

Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)

On development of a new seismic base isolation system

The objective of this paper is to examine the deformation behavior and water tightness of clay-based composite cover of landfills subjected to differential settlements using a centrifuge modeling technique. A short series of centrifuge tests were performed at 40 gravities on model composite cover system formed using a model clay barrier of 15mm (0.6m) thickness, geomembrane and overburden equivalent to that of landfill covers. The effect of presence of overlaps within the geomembrane layers at the zone of maximum curvature was also investigated. Centrifuge model test results on cover system formed with a 15mm (0.6m) thick clay barrier experienced water breakthrough once limiting distortion level is equal to 0.056. In comparison, a composite cover system formed with a 15mm (0.6m) thick clay barrier and a geomembrane was found to sustain large distortions without any water breakthrough even after subjecting to a maximum distortion level of 0.125. However, with the presence of overlaps at the zone of maximum curvature, the sealing efficiency of the composite cover with 15mm (0.6m) thick clay barrier was observed to decrease and limiting distortion level was 0.10. An attempt was also made to model the deformation behavior of barriers with and without geomembrane by finite element analysis using Plaxis 2D software. © 2012 American Society of Civil Engineers.

ASCE Geotechnical Special Publication

Centrifuge model studies on the behaviour of composite covers of landfills subjected to differential settlements

Asiafuge

Performance of Compacted Clay Barriers, Composite Barriers and Geofiber Reinforced Barriers of Landfill Covers

Indian Institute of Technology Bombay

Studies on the Behaviour of Geofiber-Reinforced Clay Barriers of Landfill Covers

Clay-based landfill covers often have a geomembrane (GM) layer sandwiching between the clay barrier and the cover soil. The knowledge pertaining to the deformation behaviour of a clay barrier along with geomembrane subjected to differential settlements is very limited. Hence, the main objective of this paper is to examine the influence of GM on the integrity of clay-based landfill covers subjected to differential settlements in a geotechnical centrifuge. First, scaling considerations required for modelling geomembrane in a centrifuge are presented. A series of centrifuge tests were performed at 40 gravities using a 4.5 m radius beam centrifuge having a capacity of 2500 g-kN available at IIT Bombay on model clay-based landfill covers with and without GM. By maintaining type moist-compacted conditions of the clay barrier as constant, the thickness of the clay barrier was varied as 0.6 m and 1 m. The performance of the clay barrier with and without GM was monitored by measuring water breakthrough at the onset of differential settlements. The analysis and interpretation of centrifuge test results reveal that with the provision of a GM and an overburden pressure equivalent to that of a landfill cover, the sealing efficiency of the cover system was found to be maintained even after the formation of full-depth cracks within 0.6 m and 1 m thick clay barriers subjected to a maximum distortion level of 0.125. This observed behaviour is attributed to the downward thrust exerted by the deformed geomembrane at the zone of maximum curvature which hinders the infiltration of water through cracks. This indicates the significant influence of GM in maintaining the sealing efficiency of a landfill cover system. © 2012 Elsevier Ltd.

Geotextiles and Geomembranes

Influence of geomembrane on the deformation behaviour of clay-based landfill covers

Effect of Microfabric on Static and Cyclic Behavior of Clays Organization of the Talk

ASCE

Performance of Composite Covers of landfills Subjected to Differential Settlements: Centrifuge Study

Equations to obtain equivalent rectangular stress-block parameters for unconfined and confined concrete are derived for rapid (hand) analysis and design purposes. To overcome a shortcoming of existing commonly used stress-strain models that are not easy to integrate, a new stress-strain model is proposed and validated for a wide range of concrete strengths and confining stresses. The efficacy of the equivalent rectangular stress-block parameters is demonstrated for hand calculations in predicting key moment-curvature results for a confined concrete column. Results are compared with those obtained from a computational fiber-element analysis using the proposed stress-strain model and another widely used existing model; good agreement between the two is observed. © 2011 ASCE.

Stress-block parameters for unconfined and confined concrete based on a unified stress-strain model

Lumber has the advantages of being a lightweight construction material, easy to handle, and environmentally benign. However, large creep deflections and significant issues with sound transmission, particularly the footfall problem, generally limit lumber use to small spans and low-rise buildings. A concrete topping on lumber subfloors may mitigate some of these issues, but even with well-engineered wood systems, the spans are relatively short. In this study, a new structural system is analytically explored. Called a lumber-boxed concrete structural system, the dual system utilizes the positive attributes of both dimensional lumber and reinforced concrete; composite action is not a requirement of the system. A stress-block approach is developed to calculate strength and deformation behavior. An analytical stress-block-based moment-curvature analysis is performed on the lumber-boxed concrete structural elements. Results show that the structural lumber-boxed concrete members may have better strength and ductility capacities when compared to an equivalent size ordinary reinforced concrete member. © 2011 American Society of Civil Engineers.