Browsing by Author "Muthukumar, G."

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Analytical Models of Damping
(ICJ, 2014) Kumar, Manoj; Muthukumar, G.
Damping is a desirable property of a structure from the earthquake resistant point of view. Thus, in dynamic analysis of structures, the modeling of damping plays a crucial role in achieving the safe response of structure. Any deviation in the representation of damping from the actual damping in the analytical model may result anything between
Behaviour of shear wall with openings - A review
(ICJ, 2017-02) Kumar, Manoj; Muthukumar, G.
A comprehensive review on applications of engineered cementitious composites in pavements
(Elsevier, 2023-12) Lahoti, Mukund; Muthukumar, G.
A significant proportion of the pavement network around the world uses asphalt as the construction material. However, asphalt reserves are expected to last no more than 50 years. The apparent alternative, Portland Cement Concrete, has its limitations, such as environmental emissions and poor riding quality. Since its inception, Engineered Cementitious Composite (ECC) has been suggested as an alternative pavement material in scattered studies over the years. This study aims to compile and present the state-of-art in ECC-related pavement applications and clearly define the research gaps so that future researchers in this area can carry out their work efficiently. It is observed that ECC has primarily been used as an overlay over both asphalt and concrete substrates rather than as a full-depth pavement material. Other application areas include bridge deck pavements, repair works, multi-layer pavements, and special function applications. Research related to the comparative life cycle and life cycle cost assessment of ECC pavements is also reviewed in this study. One significant benefit of using ECC in pavements that is noted is that slab joints can be eliminated due to the high ductility of ECC. ECC also has the potential to greatly reduce pavement reflective cracking and life-cycle environmental impacts. While the absence of coarse aggregates produces a smooth surface for excellent riding quality, it also poses the risk of low pavement skid resistance. Another important and well-known drawback of ECC, especially for such a large-scale application, is the high construction cost. Some of these problems have been solved to a certain degree using waste alternative materials and rough fine aggregates such as corundum. More research is needed to understand the prospects of ECC as a full-depth pavement material rather than just an overlay. Future work revolving around more large-scale field demonstration, durability enhancement, further cost reduction, and life-cycle impact reduction is desirable for enhanced applicability of ECC in road infrastructure.
Concrete Compressive Strength Prediction Using Boosting Algorithms
(Springer, 2023-02) Lahoti, Mukund; Muthukumar, G.
This study proposes intelligent machine learning (ML)-based methods for concrete compressive strength prediction by utilizing a publicly available dataset. The methods employed are the XGBoost, CatBoost and TabNet algorithms. A total of 1030 data points are collected wherein the independent input variables are the amounts of the different components of the concrete mix design and the output variable is the compressive strength at different curing ages. The proposed boosting algorithm approaches are contrasted with a few other popular ML techniques used in this field, such as logistic regression, classification and regression tree, and artificial neural networks. It is found that XGBoost and CatBoost show significantly lower mean errors between predicted values and actual observations of the compressive strength than the contemporary architectures, while TabNet is not so efficient. TabNet’s lower efficiency of prediction can be attributed to the relatively small dataset that was used for this study.
Design and Performance Criteria for Fire-Resistant Design of Structures – An Overview
(Springer, 2020-09) Muthukumar, G.
Concrete, despite being inherently fire resistant, cannot be considered as a fire-proof material. It undergoes substantial variation in its characteristics during exposure to elevated temperatures. These variations may become hazardous for structural stability and serviceability depending upon the type and extent of exposure. Moreover, high-strength concrete, which is commonly used in tall buildings, may perform poorly against fire due to its high binder content and very low permeability. Despite all the aforementioned factors, fire resistance design of structural members has been given very restricted consideration in the current Indian practice. Although several standards provide guidelines to achieve fire safety in structures, the provisions for high-strength concrete and spalling prevention are not specifically available in the major international and national standards. This paper attempts to compare the provisions corresponding to fire-resistant design in Indian standard with the respective provisions of other country standards, e.g., ACI 216 [3], NZS 3101 [4], EN 1992–2 [8], etc. Comparison parameters primarily include the design requirements for various structural members to improve their fire resistance. Furthermore, suitable recommendations for Indian Codal provisions are attempted in the latter part of the paper to achieve superior performance under elevated temperatures.
Failure criteria of concrete- A review
(Korea Institute of Science and Technology Information, 2014) Kumar, Manoj; Muthukumar, G.
Concrete is a versatile construction material used in many engineering structures. The design of concrete structures requires a thorough understanding of their material properties under various loading conditions. Several experimental investigations have been carried out to examine the behavior of concrete. This paper is an attempt to summarize the behavioral aspects of concrete under different loading conditions. Failure models developed out of these experimental investigations are reported in this paper with their merits and demerits.
Influence of Opening Locations on the Structural Response of Shear Wall
(Hindawi, 2014-11-25) Kumar, Manoj; Muthukumar, G.
Shear walls have been conferred as a major lateral load resisting element in a building in any seismic prone zone. It is essential to determine behavior of shear wall in the preelastic and postelastic stage. Shear walls may be provided with openings due to functional requirement of the building. The size and location of opening may play a significant role in the response of shear walls. Though it is a well known fact that size of openings affects the structural response of shear walls significantly, there is no clear consensus on the behavior of shear walls under different opening locations. The present study aims to study the dynamic behavior of shear walls under various opening locations using nonlinear finite element analysis using degenerated shell element with assumed strain approach. Only material nonlinearity has been considered using plasticity approach. A five-parameter Willam-Warnke failure criterion is considered to define the yielding/crushing of the concrete with tensile cutoff. The time history responses have been plotted for all opening cases with and without ductile detailing. The analysis has been done for different damping ratios. It has been observed that the large number of small openings resulted in better displacement response.
Influence of Shear Core Curtailment on the Structural Response of Core-Wall Structures
(Springer, 2018-08) Muthukumar, G.; Kumar, manoj
Shear walls and shear cores are the major lateral load resisting elements in multi-storeyed framed structures because of their proven track record in mitigating the damage under severe earthquake ground motions including the recent ones. The contrasting deflected profiles of shear core and frame actually help in reducing the drift of the structure. The reduction is primarily attributed to the level of horizontal interaction between cores and frames. The present study aims to simulate the horizontal interaction between core wall and frames using the dimensionless parameter () capable of characterizing the individual behaviors of the components of the dual system using the finite element analysis with different levels of curtailment of shear core. The triangular loading has been considered, and the computations have been made considering the site located in zone 4 with medium soil characteristics. To this end, in order to identify the optimum level of curtailment, an analytical study has been done on some shear core buildings with different levels of curtailment of shear core. The structural performance of the buildings with different levels of curtailment has been assessed for different parameters, namely, storey drift, deflection, bending moment, and shear forces using finite element modeling and analysis
Isolated Rectangular Footings under Biaxial Bending: A Critical Appraisal and Simplified Analysis Methodology
(ASCE, 2020) Mittal, Ravi Kant; Muthukumar, G.
The case of isolated rectangular footings being subjected to eccentric loads along both directions is very conventional as columns are ordinarily subjected to horizontal loads, vertical loads, and moments simultaneously. Also, its design has not been of much concern for engineers due to the availability of simple mathematical equations for the case when the eccentricity lies within the kern. However, the eccentricity in the case of footings subjected to high biaxial moments normally lies outside the kern area and conventional analysis becomes invalid in those scenarios. Various approximate graphical or analytical methods are available for the analysis in this case. It has been observed that most of these developed models for the biaxial bending scenario are based on the same postulation, and thus it commonly leads to confusion among designers about the most effective and straightforward method to follow during design. Therefore, to avoid the possibility of related confusion and to provide more clarification regarding the existing methods, all the available solutions for the design of the biaxially eccentric condition are critically reviewed in the present study. Moreover, recommendations are proposed for the use of a simple method based on a justifiable comparison highlighting the shortcomings in the applications of other available solutions. Additionally, to enhance the computational efficiency of computer-aided studies and manual assessments, a simplified approach to automate the recommended procedure for the design of rectangular footings is also developed, and correspondingly a pseudoalgorithm is proposed for its easy implementation.
Post-Earthquake Assessment of Buildings Using Deep Learning
(2019-07) Muthukumar, G.
Classification of the extent of damage suffered by a building in a seismic event is crucial from the safety perspective and repairing work. In this study, authors have proposed a CNN based autonomous damage detection model. Over 1200 images of different types of buildings-1000 for training and 200 for testing classified into 4 categories according to the extent of damage suffered. Categories are namely, no damage, minor damage, major damage, and collapse. Trained network tested by the application of various algorithms with different learning rates. The most optimum results were obtained on the application of VGG16 transfer learning model with a learning rate of 1e-5 as it gave a training accuracy of 97.85% and validation accuracy of up to 89.38%. The model developed has real-time application in the event of an earthquake.
Resilience Based Earthquake Design of Buildings: Current Practice, Problems, and Opportunities in Indian Scenario
(ASCE, 2018) Muthukumar, G.
Resilience based design (RBD) gives an advantage in designing for both direct and indirect losses. It was observed that most significant losses to the economy is due to indirect losses incurred due to long downtime—inability of common mass to resume to their jobs and return home. With the use of RBD methods it is possible to control the downtime and its losses. In Indian scenario one of the major problem associated with carrying out RBD is lack of ground motion database and guidelines for selection and scaling ground motions. It is required to have hazard consistent ground motions to perform non-linear time history analysis (NLTHA) and using this analysis results, downtime assessment such as repair cost, repair time along with direct loss could be assessed. In this paper, current practices and their limitation in resilience based earthquake design are discussed along with the selection of proper ground motion and scaling methods. This paper also suggests various alternative methods such as use of SPO2IDA in cases where hazard consistent ground motion cannot be produced easily.