Devdas Menon

Bio: Devdas Menon is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Slab & Deflection (engineering). The author has an hindex of 10, co-authored 50 publications receiving 388 citations. Previous affiliations of Devdas Menon include Indian Institutes of Technology.

Multivariate Simulation and Multimodal Dependence Modeling of Vehicle Axle Weights with Copulas

Abstract: Safety assessment and rational design of bridge structures requires the uncertainty associated with vehicle loads to be modeled as accurately as possible. This modeling is rendered difficult by the presence of vehicle axle weights that involve different combinations of unimodal and multimodal probability distributions with different dependence structures. In this paper, a transformation invariant approach using copula functions is proposed for the multivariate simulation of dependent axle weights of different vehicle classes. Copula based dependence modeling, which is widely used in the financial risk analysis, is applied to model and simulate three different vehicle cases with different combinations of marginal probability distributions for axle weights. The database of observed vehicle weights is based on the data collected at five locations on national highways in India. The dependence between multimodal distributions of axle weights is accurately considered and simulations are carried out. The simulated axle weights are found to be in very good agreement with the observed data. This type of simulation is useful in carrying out simulation-based reliability analysis of bridges and pavements.

Evaluation of dynamic load on railtrack sleepers based on vehicle-track modeling and analysis

Abstract: The present study reports the results of a rigorous dynamic interaction analysis that accounts for the vehicle-track characteristics and rail imperfections. In order to perform a rigorous dynamic analysis, a model involving all components of the track structure and vehicle parameters are required. A vehicle model (conforming to Indian Railways) with 17 degrees of freedom has been considered. The track model consists of rail, rail-pad, sleeper, ballast, sub-ballast, subsoil and a track length encompassing 12 prestressed concrete sleepers. The dynamic interactive analysis is carried out between the vehicle and track in the time domain using a finite element software. The results of the interactive analysis give responses in the form of reaction time histories at the rail-seat locations during the passage of vehicle. A parametric study is carried out to assess the influence of different track parameters on the dynamic load on the railtrack sleepers. Based on this study, suitable load amplification factors are arrived at to facilitate an improved design basis for an equivalent static analysis in practical designs of sleepers.

A review of loading conditions for railway track structures due to train and track vertical interaction

Abstract: Train and track interactions during services normally generate substantial forces on railway tracks. Such forces are transient by nature and of relatively large magnitude and are referred to as impact loading. There has been no comprehensive review of the typical characteristics of the loading conditions for railway track structures, in particular, impact loads due to the wheel/rail interaction, published in the literature. This paper presents a review of basic design concepts for railway tracks, abnormalities on tracks, and a variety of typical dynamic impact loadings imparted by wheel/rail interaction and irregularities. The characteristics of typical impact loads due to wheel and rail irregularities, e.g. rail corrugation, wheel flats and shells, worn wheel and rail profiles, bad welds or joints, and track imperfections, are presented with particular emphasis on the typical shapes of the impact load waveforms generally found on railway tracks. Copyright © 2007 John Wiley & Sons, Ltd.

Wind loading of structures

Abstract: The static and dynamic approaches to the determination of design wind loads have been summarised along with the various assumptions, approximations and limitations involved. The application of these two approaches using the Australian Standard AS1170.2 is discussed along with comparisons from wind tunnel measurements.

Building Information Modeling (BIM) Application in Malaysian Construction Industry

Abstract: Bu ilding Informat ion Modeling (BIM) is a set of digital tools that can manage construction projects effectiveness. BIM has been used by the Architecture, Engineering and Construction (AEC) industries in Malaysia. The idea to imp lement BIM in Malaysia was introduced by the Director of Public Works Depart ment (PWD) in 2007. The aim of this paper is to exp lore BIM imp lementation in Malaysian construction industry. A literature review was done to exp lore previous BIM studies on definitions and history of BIM, construction issues, application of BIM and BIM tools in construction projects as well as benefits of BIM . Malaysian government encourages construction players to apply BIM to construction projects because it can overcome construction project problems such as delay, clash of design by different professionals and construction cost overrun. Autodesk tools have been suggested by the government as a BIM tool platform. Other tools include Revit Architecture, Revit St ructural, Revit M EP, Navisworks and Cost-X. It is crucial for construction players to be aware of the importance of BIM applicat ion in construction projects. This is because BIM can be one of the conditions required of a co mpany to qualify for government and private projects, similar to what is practiced in some other countries. Moreover, BIM helps to increase construction project efficiency and effectiveness. It can also be imp lemented to improve commun ication and collaboration between construction players. The implementation of BIM technology is expected to become mo re widespread in Malaysian construction industry because of the government's effo rts in pro moting BIM .