Vasant Matsagar

Indian Institute of Technology Delhi | IIT Delhi · Department of Civil Engineering

A contemporary policy gradient-based optimization scheme is presented for active structural control by exerting the concept of reinforcement learning (RL). The RL-based control algorithm is demonstrated both in proportional (P) state, and proportional-integral (PI) state-output feedback approaches, wherein, the latter strategy is deliberated based...

Anchor channels are commonly used for façade, tunnel, and structural connections. These connections encounter various types of loadings during their service life, including high rate or impact loading. For anchor channels that are placed close and parallel to an edge and loaded in shear perpendicular to and towards the edge, the failure is often go...

Base isolation technology is highly advocated by the research community worldwide for efficient miti-gation of earthquake-induced vibrations and alleviating seismic risks posed to civil engineering structures. However, the construction cost of implementing this advanced technique to real-life buildings compared to the conventional ones remains a de...

The application of composite materials has increased manifolds in aerospace and high-speed vehicle industries, where structures experience dynamic loads along with temperature variation. To ensure safety of these structures, the stochastic dynamic analysis in varying thermal environments is essential. The generalized polynomial chaos (gPC) expansio...

The use of carbon Fiber-Reinforced Polymers (CFRP) for reinforcing and prestressing concrete structures is a promising alternative in the infrastructure industry. Particularly, prestressed concrete members reinforced with such polymeric materials are becoming popular to evade corrosion-related issues. The conventional simply supported bridge requir...

In the finishing phase of the conventional manufacturing process of foams, the outer skin of the foam is usually removed. In the present investigation, the effect of outer skin is considered to understand its effect on the impact-resistance and energy absorption behavior of the foam. An assessment of the impact-resistance of various foams is carrie...

Lifeline structures such as hospital buildings need to be specifically designed such that they experience reduced vibrations when subjected to earthquake excitations because it will be difficult to vacate hospital buildings under the event of any earthquake. Therefore, to ensure operational condition under earthquake excitations in an existing hosp...

Lifeline structures such as hospital buildings need to be specifically designed such that they experience low levels of vibration when subjected to earthquake excitations. This is necessary since it is not easy to evacuate hospital buildings during earthquakes. This study aimed to utilize flexible unbonded fibre-reinforced elastomeric isolators (UF...

In present study, the influence of glass wool fiber (GWF) reinforcements and the application of heat resistant paint has been studied on the performance of self-compacting mortar (SCM) at ambient condition and at elevated temperatures of 200 • C, 400 • C, 600 • C, and 800 • C. Sixteen mix designs were prepared for SCM (with 25% fly ash) using GWF r...

High-strength composite materials are receiving increased attention within the aerospace and transportation industries. These materials, although light in weight, still impart high stiffness when compared to conventional structural materials, e.g., aluminum and steel. Fibers and matrix are the basic constituents of composite materials. During high-...

Conventional structural materials are being replaced by advanced composite materials owing to their superior mechanical properties. Basalt fiber-reinforced polymer (BFRP) is the latest fiber-reinforced polymer (FRP) composite material introduced as reinforcement and pre-stressing tendons for reinforced concrete (RC) and pre-stressed concrete (PSC)...

In this chapter, the fire resistance requirements for structural components incorporating bio-based fiber-reinforced polymer composites are presented. The factors that are to be accounted for in evaluating the performance of fiber-reinforced polymer (FRP) structural members at elevated temperatures are discussed. In addition, the various steps asso...

This paper presents a numerical study to evaluate the fire resistance of concrete beams and slabs incorporating natural fiber-reinforced polymers (FRP). A validated finite element model was applied to carry out a series of numerical studies on fire-exposed reinforced concrete (RC) beams and slabs strengthened with conventional and bio-based FRP com...

Nonlinear finite-element (FE)-based quasi-static and vibration analyses of prestressed concrete beams with carbon fiber-reinforced polymer (CFRP) laminate are conducted. To establish nonlinearities in concrete and prestressing steel material properties and concrete–steel interfaces in FE modeling, numerical models of reinforced concrete (RC) and pr...

The implementation of machine learning for the real-time prediction of the suitable value of the damping ratio of a semi-active tuned mass damper (SA-TMD) is investigated to ensure enhanced vibration control in vehicle-bridge interaction (VBI) problems. The response assessment of the uncontrolled, tuned mass damper (TMD)-controlled, and SA-TMD-cont...

Detailed design of a base-isolated building as per Indian code provisions and practices is made and described here to facilitate corroboration of the design with other international codes and standards. Upon reviewing the latest developments and applications of the base isolation technology in India, the code development is presented. Particularly,...

Earthquake engineering and technology has been dealt with by introducing different sub-disciplines thereof, contemporary practices, and the latest developments. Upon giving background to open-up various topics, the expertise required and professionals involved in various disciplines have been systematically presented by giving information exchanges...

Basalt fiber-reinforced polymer (BFRP) composite is one of the promising structural materials recently introduced to the construction industry as internal reinforcement for the purpose of prestressing concrete. In this study, experimental and analytical investigations have been carried out to assess the flexural performance of BFRP-prestressed conc...

Sandwich panels have wide applicability in blast- and impact-resistant design of structures due to their phenomenal energy absorption capacity, albeit being considerably light in weight. A sandwich panel consists of core(s) and facesheets, wherein the core contributes majorly to the energy absorption capacity and the facesheets contribute the stiff...

Liquid storage tanks are strategically important due to their essential requirement of service in the post-earthquake situation. Numerical modeling of the liquid storage tank needs special attention and cannot be done in the same manner as that of the conventional buildings. In the present paper, a numerical simulation of the RC elevated liquid sto...

Wind and/or earthquake-imposed loadings on two dynamically similar adjacent buildings cause vigorous shaking that can be mitigated using energy dissipating devices. Here, the vibration response control in such adjacent structures interconnected with semi-active magneto-rheological (MR) dampers is studied, which could also be used as a retrofitting...

Performance-based structural design is still in a comparatively developmental phase for fire hazard when compared to that of, for example, earthquake excitation. Addressing a significant weakness in performance based design for fire, the present study aims to propose appropriate intensity measures (IM) for a fire hazard that has a robust correlatio...

The paper presents the use of semi-active magneto-rheological (MR) dampers for the structural response reduction of the reinforced concrete (RC) elevated liquid storage tanks. The effectiveness of MR dampers is investigated based on the control strategies and the placement of the dampers in the staging. The RC elevated liquid storage tank is modele...

Analytical framework for probabilistic assessment of dynamical system under base- and mass- excitations with equal input energy is presented with reference to multi-hazard engineering. Closed-form solutions for equivalent undamped and damped dynamical systems under harmonic sinusoidal base- and mass- excitations are obtained. Uncertainties are cons...

Composite materials are increasingly used in aerospace and automobile sectors. These materials are characterized by high stiffness and light-weight in comparison to conventional structural materials. During high-speed maneuvering of these vehicles, associated composite structures are subjected to dynamic loadings and are often exposed to varying th...

High-strength and lightweight composites used in high-speed vehicles and aircraft experience increased temperature owing to aerodynamic friction. Because of the rise in temperature, the elastic moduli of the composites are degraded and inherent viscous damping is increased to the glass transition temperature. In this work, the damping performance o...

The seismic isolation of ground-supported cylindrical liquid storage tank using the newly developed oblate spheroid base isolation (OSBI) system is investigated. The OSBI is an ellipsoidal-shaped isolator in both of its horizontal axes and dissipates seismic input energy in rolling friction apart from period lengthening achieved through the oblaten...

Service-life damage in reinforced concrete (RC) structure caused due to the actions of earthquake and cyclonic wind, and their multi-hazard effects is evaluated, by considering them as independent (uncorrelated) non-cascading hazards with and without considering the effects of chloride-induced corrosion in the structural members. Behavior of a stru...

Unbonded fiber-reinforced elastomeric isolator (UFREI) is a valuable substitute to the conventional elastomeric isolators for seismic base isolation purpose. The use of fiber reinforced polymer sheets in place of steel reduces the cost of the isolation system considerably, thus making it affordable to a variety of low-cost construction projects. Mo...

The stochastic response of multi-story buildings isolated by laminated rubber bearing (LRB), lead-rubber bearing (N-Z system), friction pendulum system (FPS), and resilient-friction base isolator (R-FBI) is investigated under the independent multi-hazard scenario of earthquake ground motion (EQGM), wind load (WL), and blast-induced ground motion (B...

The design codes/standards recommend using an over-reinforced beam section for FRP-reinforced structures to use the ductility of concrete to give adequate warning prior to complete failure. In contrast, the present study is based on the nonlinear response prediction of beams prestressed with carbon-fiber- reinforced polymer (CFRP) tendons and desig...

Recent research trends focus on developing bio-based (derived from agricultural byproducts) fiber-reinforced polymer (FRP) composites for structural applications. Fire resistance is one of the key issues that need to be addressed for the use of these FRP materials in buildings. The thermal and mechanical properties of the constituent materials esse...

Urban cities worldwide are filled with low‐rise to high‐rise buildings which may be vulnerable to both earthquake and wind excitations depending on their locations. Here, the performance of optimally designed nonlinear tuned mass dampers (TMDs) is evaluated for the vibration control of multi‐story structures under the multi‐hazard scenario. The fun...

The effect of semi‐active pseudo‐negative stiffness dampers (SAPNSDs) on the seismic response mitigation in the reinforced concrete (RC) elevated liquid storage tanks is investigated. The SAPNSDs are operated in two modes: Passive‐ON and Passive‐OFF. The effect of placement (location) of the dampers is also studied by placing the dampers in three d...

In a terrorist attack, structural elements such as, reinforced concrete (RC) wall panels have a relatively higher degree of exposure to blast loading which has the potential to trigger devastating fire hazard. As a result, there is significant limitation to the load carrying capacity of the structure, thereby leading to early collapse of structure....

Shear lag is one of the governing phenomena considered in the design of flanged flexural members. The effect of the location of load on shear lag is not well understood yet. This paper presents a study to understand the shear lag behavior in the concrete slab of bonded steel-concrete composite flexural members, conducted with the help of a develope...

Multiple hazards, such as, earthquake, strong wind, snow, flood-induced scour, tsunami, landslide, rain, blast, explosion, fire outbreak, etc. have caused extensive global devastations to civil structure and infrastructure systems in terms of physical and socio-economic losses. The catastrophic losses are largely due to the complex effects of these...

Corrosion of steel tendons/reinforcements has been a major concern in the prestressed concrete (PSC) and reinforced concrete (RC) beams used in bridge construction. In order to overcome this drawback, basalt fiber-reinforced polymer (BFRP) tendons have been introduced to replace the steel tendons/reinforcements. However, the major limitation with s...

In this paper, the influence of soil-structure interaction (SSI) on a torsionally coupled turbo-generator (TG) machine foundation is studied under earthquake ground motions. The beneficial effects of base isolators in the TG foundation under earthquake ground motions are also studied duly, considering the effects of SSI. A typical TG foundation is...

The interdependencies between various risks imposed by natural as well as accidental/ manmade hazards demand a holistic design approach to ensure structural safety through multi-hazard engineering. In this regard, the present article provides guidelines and recommendations for design of structure and infrastructure systems under multi-hazard scenar...

For millennia bridges have been used to cross barriers, typically a river, stream, or valley, by using locally available materials, such as stones, timber. Originally, cut trees were simply placed across streams to allow crossing. Later, pieces of wood were lashed together to make the improvements in functionality of the bridges. Such bridges are k...

For millennia bridges have been used to cross barriers, typically a river, stream, or valley, by using locally available materials, such as stones, timber. Originally, cut trees were simply placed across streams to allow crossing. Later, pieces of wood were lashed together to make the improvements in functionality of the bridges. Such bridges are k...

Earthquake response control of base-isolated bridges using supplementary passive dampers is presented. A benchmark highway overcrossing located in California is selected to indicate the effectiveness of such hybrid response control schemes. The bridge is modeled as a lumped mass three-dimensional stick model. The coupled differential equations of m...

The capacity factor (CF) and power coefficient (Cp) are two important wind turbine characteristics. CF describes the power generation capacity during a given period, and Cp describes the efficiency of the wind turbine. Both quantities depend on the rated wind speed. Determining the optimal rated wind speed that maximizes a function of CF and Cp tha...

Over the last decade, excessive devastations caused by extreme events, such as blast loading have raised significant concern on the performance of civil structural systems. Despite realizing the importance of inherent risk associated with this phenomenon, most of the studies neglected the effects of uncertainties associated with the system, wherein...

Recent terrorist activities in the form of blast and its cascading effects in the form of fire have had devastating impacts in structures, posing serious safety issues in structural members. In this context, a numerical study is conducted here to investigate the mechanics of damage in a reinforced concrete (RC) wall panel exposed to post- blast fir...

Basalt fiber–reinforced polymer (BFRP) has been the most recent fiber–reinforced polymer (FRP) composite material introduced as reinforcement and prestressing tendons for concrete. Measuring the mechanical properties of BFRP rod/tendon is challenging using the existing mechanical testing methods due to their relatively lower transverse direction st...

Base shear and sloshing response control in ground-supported circular cylindrical liquid storage tank is achieved by oblate spheroid base isolation (OSBI) system used along with floating surface diaphragm on the contained liquid. The new base isolation system, OSBI proposed herein is based on rolling-friction mechanism in ellipsoidal-shaped isolato...

Use of basalt fiber-reinforced polymer (BFRP) rebars has lately been introduced as an effective means for replacement of the conventional steel reinforcement in concrete structures owing to their relatively superior physical and mechanical properties. In the present study, BFRP-prestressed concrete (BFRP-PSC) beams have been designed, analyzed, and...

Laminate composite plates have several significant applications in aerospace and automobile industries due to their high strength-to-weight ratio, thermal stability, etc. However, thin laminated composite plate has a tendency of buckling when subjected to some adverse loading conditions. The addition of stiffener can avoid the buckling tendency of...

Hazards such as fire, blast or severe seismic event may cause a local failure of columns leading to disproportionate or progressive collapse of a structure. Progressive collapse is a complex dynamic process greatly influenced by several factors including the integrity and tie-strength of beam-and-slab system over the damaged column, load-redistribu...

The issues of safety and posthazard functionality of structures under multihazard scenarios are some of the significant challenges in the current dynamic and rapidly growing urban environment. In this paper, multistory base-isolated buildings are investigated under the independent multihazard scenario of earthquake and blast-induced ground motion (...

The numerical investigation on the seismic response of RC elevated liquid storage tanks installed with viscous dampers is presented. A discrete two-mass model for the liquid and multi-degree of freedom system for staging, installed with the dampers are developed for Reinforced Concrete (RC) elevated liquid storage tanks. The elevated tank is assess...

Japan experiences a considerable number of low to medium earthquake shocks and long-duration winds throughout the year, which is relatively more as compared to other different regions of the world. Considering this multi-hazard scenario , structures designed using the existing guidelines may have significant chances to underestimate the induced dis...

Despite realizing the importance of risk-based frameworks in fire engineering, current fire safety guidelines are largely prescriptive and over-conservative in nature, which do not consider the effect of uncertainties influencing the fire resistance of the structural systems. In this context, a probabilistic framework is presented to investigate vu...

Adhesive bonding has recently emerged as an alternative to shear stud connection in steel-concrete composite flexural members. Research on adhesive-bonded steel-concrete composite flexural members is in a preliminary stage, and the behavior of the bond layer in these structures is not well understood yet. A three-dimensional finite element model is...

Effectiveness of friction dampers (FDs) is investigated for connected dynamically similar and dissimilar steel buildings under uncorrelated seismic ground motion and wind excitations. The steel buildings involving moment-resisting frame (MRF) and braced frame (BF) are varied from five storeys to twenty storeys, which are connected by different conf...

Multistory building construction projects involve time and economy considerations. In this study, an approach to determine a time-optimized solution for speedy construction using a genetic algorithm for a multistory building is used. An objective function is formulated for minimizing the reinforced cement concrete (RCC) work duration, subject to ce...

The multi-hazard effects on multi-story steel buildings equipped with energy dissipative passive vibration response control devices are investigated for their performance under earthquake-and wind-induced forces. The passive response control devices include steel bracings, viscous, and viscoelastic dampers. The buildings without and with the passiv...

Purpose Despite recognizing the significance of risk-based frameworks in fire safety engineering, the usual approach in structural fire design is largely member/component level, wherein effect of uncertainties influencing the fire resistance of structures are not explicitly considered. In this context, a probabilistic framework is presented to inve...

For millennia bridges have been used to cross barriers, typically a river, stream, or valley, by using locally available materials, such as stones, timber. Originally, cut trees were simply placed across streams to allow crossing. Later, pieces of wood were lashed together to make the improvements in functionality of the bridges. Such bridges are k...

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A seismic analysis of ground-supported, three-dimensional (3-D) rigid-base steel cylindrical liquid storage tank is investigated, using a coupled acoustic-structural finite element (FE) method for fluid-structure interaction (FSI). In this method, the contained liquid in the tank is modelled using acoustic elements and the cylindrical tank is model...

With the development of technology, mud plaster has been replaced by cement plaster for supporting bamboo mesh in wall panels and known as ekra wall or bamcrete wall. Usually, low grade mortar is used in making the bamcrete wall, while the latest studies have used high strength mortar. Bamboo burns through pyrolysis process like wood when it is exp...

The effectiveness of a tuned mass damper (TMD) in dynamic vibration mitigation of a 20-storey steel benchmark structure (SBB) under real earthquake ground motions is presented. To study the positioning and tuning effect, a TMD is positioned at the largest or relatively larger of the normalized amplitude of mode shape of the selected structure. At e...

This article focuses on investigating vulnerability of fire-exposed reinforced concrete (RC) panels under transverse out-of-plane and compressive in-plane loads following a probabilistic methodology. The three-dimensional (3-D) RC panels are modeled by considering material and geometric nonlinearity and subsequent transient thermo-mechanical analys...

The present study deals with three-dimensional (3-D) nonlinear finite element (FE) analyses of tunnel with curved alignment in the longitudinal direction, subjected to internal blast loading. Blast load is simulated using the coupled Eulerian Lagrangian (CEL) analysis tool available in FE software Abaqus/Explicit. The explosive and the surrounding...

The efficiency of tuned mass dampers (TMDs) in along-wind response mitigation of a wind turbine with consideration of blade coupling and soil-structure interaction (SSI) is investigated. The wind turbine tower is modeled as a multi-degree of freedom (MDOF) with three blades are connected as a MDOF system to the tower. The along-wind drag forces are...

Vibration analysis of a thin circular cylindrical shell with closure is conducted using finite element method (FEM). Theoretically, shell vibrates in different axial modes, m; circumferential modes, n; and any of their combinations with corresponding modal frequencies. The present FEM results are verified by the results reported in the literature u...

The aim of the present study is to investigate the efficiency of the torsional tuned mass dampers (T‐TMDs) in response control of asymmetric buildings under bidirectional earthquake ground excitations. The efficiency of the T‐TMDs is compared with bidirectional tuned mass dampers (BTMDs). The T‐TMDs are oriented to the rotation of the structures ab...

Dynamic response of base-isolated buildings under uni-directional sinusoidal base excitation is numerically investigated considering uncertainties in the isolation and excitation parameters. The buildings are idealized as single degree of freedom (SDOF) system and multi-degrees of freedom (MDOF) system with one lateral degree of freedom at each flo...

Response analysis of structural systems under impulse loading is extremely important for appropriate design against accidental loads such as blast. Herein, the response of elastic and inelastic single degree of freedom (SDOF) systems with uncertain parameters under random impulse loadings is investigated. Four different types of impulse loading pro...

A finite element (FE)-based numerical model is developed in ABAQUS®, to evaluate the response of steel fiber reinforced concrete (SFRC) columns under combined effects of fire and structural loading. The model utilizes a sequentially coupled thermo-mechanical analysis procedure to trace the fire response of concrete columns. The FE model accounts fo...

Increased application of carbon fiber reinforced polymer (CFRP) composites to resist blast loadings necessitated investigating their dynamic behavior. It requires characterization of the CFRP laminates at high strain rates using split Hopkinson pressure bar or comparable device. In this investigation, tensile properties of the CFRP laminates subjec...