IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

The Indian earthquake problem is well known. About 60% of India's land area is considered prone to shaking of Modified Mercalli intensity VII and above (IS:1893-2002). In fact, the entire Himalayan belt is considered prone to great earthquakes of magnitude exceeding 8.0, and in a span of 53 years, four such earthquakes occurred: 1897 Assam, 1905 Kangra, 1934 Bihar-Nepal, and 1950 Assam-Tibet (Table 1). As seen in Table 1, there have not been any M &gt; 8.0 earthquakes in India since 1950. However, a very large number of deaths occurred in the M 6.4 Latur (1993) and...&nbsp;

Department Of Civil Engineering

World University root node

Seismological Research Letters

Some innovative education and outreach projects in India for Earthquake risk reduction

The flexure and shear design philosophies of different international codes of practice for reinforced concrete (RC) structural walls are reviewed. The role of capacity design philosophy is discussed from the point of view of ductile flexural failure during strong earthquake shaking. The current design provisions of walls given in the Indian codes of practice, especially in IS 13920:1993, are critically reviewed in light of the international practice. The deficiencies in the current seismic design provisions are highlighted and possible improvements in the code provisions are identified.

Indian Concrete Journal

Seismic shear design of RC structural walls - Part I: Review of code provisions

Masonry buildings are brittle structures and one of themost vulnerable of the entire building stock under strong earthquake shaking. Thus, it is very important to improve the seismic behavior of masonry buildings. A simple way of making Masonry Walls behave well during earthquake shaking is by making them act together as a box along with the roof at the top and with the foundation at the bottom.

How do brick masonry houses behave during earthquakes?

Journal of Structural Engineering (Madras)

Learning earthquake design and construction earthquake Tip - 14 - Why are horizontal bands necessary in masonry buildings?

Learning earthquake design and construction Earthquake Tip - 15 - Why is vertical reinforcement required in masonry buildings?

Part I of this paper1 reviewed the code provisions on seismic shear design of RC bridge piers. The second part, presented here discusses the numerical investigation of IRC provisions. In this paper, monotonic lateral load-deformation relations of reinforced concrete (RC) bridge piers, designed as per existing IRC standards and bending in single curvature, are analytically studied. A displacement-based pushover analysis procedure is developed for the purpose. The analysis shows that the design shear capacities of short piers are lower than the corresponding shear demand under flexural overstrength conditions. Also, buckling of longitudinal reinforcement is commonly observed, which results in rapid strength loss and subsequent failure of piers. Thus, the current transverse reinforcement requirements of the Indian code are inadequate. Also, additional radial links in hollow circular piers are found to enhance the displacement ductility; the current code does not have any reference to this. The Indian seismic bridge design provisions need to be revised urgently.

Seismic shear design of RC bridge piers - Part II: Numerical investigation of IRC provisions

This paper describes an experimental study of beam-column joints in frames common in preseismic code/gravity-designed reinforced concrete (RC) frame buildings. Exterior RC joint subassemblages were studied with four details of longitudinal beam bar anchorage and three details of transverse joint reinforcement. All these specimens showed low ductility and poor energy dissipation with excessive shear cracking of the joint core. Joint shear stresses greater than ACI-specified limiting values were mobilized in these small volume joints. The ACI standard hook for anchorage of the longitudinal beam bars and the suggested hairclip-type transverse joint reinforcement were found to be more effective. This combination of anchorage and joint reinforcement is easy to construct and can be used in moderate ductility demand situations.

ACI Structural Journal

Effectiveness of reinforcement details in exterior reinforced concrete beam-column joints for earthquake resistance

Learning earthquake design and construction Earthquake Tip - 16 - How to make stone masonry buildings earthquake resistant?

The paper reviews the seismic strength design provisions for reinforced concrete (RC) bridge piers given in American, Japanese, New Zealand, and Indian codes. In seismic design of RC compression members like piers, ductility can be ensured through adequate transverse reinforcement calculated based on capacity design concept. The comparison of the available Indian code provisions with those of the international ones indicates that earthquake resistant design of piers is not formally addressed in the Indian codes. The paper is presented in two parts; the first presented here, reviews the strength and ductility design provisions in the Indian code in the light of the provisions in some of the international codes. The second part, to be published later, deals with the numerical investigation of the RC bridge piers designed to conform to the current Indian code provisions.

Seismic shear design of RC bridge piers - Part I: Review of code provisions

Particulate solids are ubiquitous in our daily lives. Uniform mixing and controlled segregation of particulate solids is the key to success of many industrial processes. However, the complex nature of particle interactions has defied a good understanding of particle mixing. A simple system such as a sand pile at rest with a slope less than the angle of repose behaves like solid material that remains at rest. If the same pile is tilted several degrees above the angle of repose particles start to flow like a fluid. This simple observation that embodies the richness and complexity of particle motion have led to years of research effort both from the theoretical as well as practical standpoint. While the physicists are trying to establish connections between granular dynamics and processes taking place on an astrophysical scale, many industries on a daily basis simply struggle with solid mixing to obtain products of an acceptable quality. The mixing process is typically carried out in relatively simpler equipment such as a rotating drum. Here mixing is influenced profoundly by the flow characteristics of the particulate matter to be mixed. The purpose of the paper is to study mixing and segregation of particles by elucidating some of the flow characteristics in rotating drum.&nbsp;

Third International Conference on Discrete Element Methods

Mixing and Segregation of Particles in Rotating Drums using the Discrete Element Method

Earthquake tip

Recent studies on connections have shown that the beam bending theory cannot predict the flow of forces near the connection regions. In this paper, a new truss analogy model has been proposed to better represent the flow of forces near the column base connections. Also, shear-moment strength envelopes, generated for different levels of axial load using the hysteretic stress-strain curves for steel, are presented. The moment and shear demand for the design of column base connection elements are calculated using the normalized P-V-M interaction curves. Appropriate strength factors applied to the moment capacity of the column section to account for the uncertainty in the estimation of yield stress, strain hardening, compactness of the section, and slenderness of the member are discussed. Finally, a generalized procedure for the capacity design of column base connections is proposed.

Engineering Journal

P-V-M interaction curves for seismic design of steel column base connections

Anchorage details and joint design in seismic RC frames (multiple letters)

Twist in buildings, called torsion, makes different portions at the same floor level to move horizontally by different amounts. This induces more damage in the columns and walls on the side that moves more. It is best to minimize this twist by ensuring that buildings have symmetry in plan.

How buildings twist during earthquakes?

The discrete element method (DEM) has been used extensively in simulating multiple interacting bodies undergoing relative motion and breakage. The key to the success of this method lies in correctly establishing the interaction rules and the associated contact parameters. In this paper, this is done by analyzing the impact behavior of a steel ball. Experimental data using an ultra fast load cell (UFLC) allowed the material response at the contact to be adequately modeled by a nonlinear differential equation. In turn, the contact parameters to be used in the DEM were directly extracted from the model.The nonlinear contact behavior led to values of contact parameters that limit the critical time step in the numerical integration. This is unsuitable for any large simulation involving thousands of interacting balls as in the case of a ball mill. This disadvantage is overcome by using the equivalent linearization technique to transform the nonlinear contact model to an analogous linear model. Not only did the linearized parameters allow a larger time step but also the use of a linear spring-dashpot model significantly reduced the overall computational effort, which is illustrated by simulating a 54.5-cm diameter ball mill. Copyright © 2001 Elsevier Science B.V.

Powder Technology

On the determination of contact parameters for realistic DEM simulations of ball mills

Torsional failure of elevated tanks has occurred in past earthquakes. The overall axisymmetric structural geometry and mass distribution of such structures may leave only a small accidental eccentricity between centre of stiffness and centre of mass. Such a small accidental eccentricity is not expected to cause a torsional failure. This paper studies the possibility of amplified torsional behaviour of elevated water tanks due to such small accidental eccentricity in inelastic range through detailed case studies; using two simple idealized systems with two coupled lateral-torsional degrees of freedom and, strength-deteriorating and elasto-plastic hysteresis models. The systems are capable of retaining the characteristics of two extreme categories of water tanks namely, (a) tanks on staging with less number of columns and panels and (b) tanks on staging with large number of columns and panels. The study shows that the presence of a small eccentricity may lead to localized unsymmetrical yielding in some of the reinforced concrete staging elements. This may lead to progressive strength deterioration through successive yieldings in same elements under cyclic loading during earthquakes. Such localized strength drop may increasingly develop large strength eccentricity resulting in large localized inelastic displacement and ductility demand, leading to failure. These observations are also verified for a real-life example elevated tank. The tanks supported on staging with fewer columns and panels are found to have greater torsional vulnerability. The tanks located near a fault are found to be vulnerable under near-fault pulses with a large duration compared to the lateral period of tank. © 2001 Academic Press.

Journal of Sound and Vibration

Inelastic seismic torsional behaviour of elevated tanks

Preliminary field report on Gujarat earthquake

The fourth revision of the Indian standard code of practice for plain and reinforced concrete, IS 456 has made significant headway in the provisions related to concrete engineering. However, it is observed that most of the provisions related to reinforced concrete (RC) design engineering that were present in the third revision remain untouched. Even the few provisions that were added, namely, those related to design of RC walls and shear design of beams, seem to be inconsistent with the basic understanding of structural behaviour. The provisions regarding design of RC walls do not mention the need for the axial load-bending moment interaction to be considered in their design; which could be considered as a conceptual error introduced in the new revision. The provision on design of shear in beams is based on a narrow perspective of structures designed to resist only static loads. This point of view shows how the new code in the current form can lead to nonconservative designs. Therefore, a comprehensive revision of the RC design engineering provisions is urgently required.