Browsing by Author "Singh, Shamsher Bahadur"

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Advances in Concrete, Structural & Geotechnical Engineering
(Bloomsbury India, 2018) Singh, Shamsher Bahadur
Advances in Construction Materials and Management
(Springer, 2023) Singh, Shamsher Bahadur
This book presents the select papers from the proceedings of the National Conference on Advanced Construction Materials and Management (ACMM 2022). The book discusses the ongoing research and advanced practices in building materials and construction project management. Various topics covered in the book include new/alternate/supplementary construction materials, deterioration mechanisms in construction materials, microstructure characteristics of concrete, special and recycled aggregate concretes, advanced construction techniques, contracts and arbitration, building information modeling (BIM), prefabricated and modular construction, augmented reality (AR) and virtual reality (VR) in construction management, and artificial intelligence and machine learning in construction. The book is a useful reference for researchers and professionals working in the fields of construction materials and management.
Analysis and Design of FRP Reinforced Concrete Structures
(McGraw-Hill Education, 2015-03) Singh, Shamsher Bahadur
Analysis and Design of Prestressed Concrete Structures
(Wiley, 2023) Singh, Shamsher Bahadur
This book on analysis and design of prestressed concrete structural elements is an advance design course for undergraduate and post-graduate students, research scholars, and practitioners. Analysis and design of prestressed concrete elements using both the pre-tensioning and post-tensioning systems are discussed in detail for determinate as well as indeterminate framed structures with detailed design examples.
Analysis And Strengthening Of Stone Masonry Structures
(CECR, 2021-11) Singh, Shamsher Bahadur
This paper presents a powerful analytical tool based on the limit analysis methodology to estimate the stability of the stone masonry structures, especially structures such as arches, vaults and domes. The approach provided is largely 2-dimensional, but with some approximation it can also be applied to complex 3-dimensional problems. Further, the strengthening of unstable masonry arches is studied with the help of composites such as FRPs, which show excellent properties of high tensile strength and stiffness. The analysis is based on the stress results obtained through the linear finite element analysis in ABAQUS and thrust line analysis to evaluate the stability of unstable masonry arches. Furthermore, some recommendations have been provided to expand this work in the future along with the limitations of the present work.
Analytical assessment of dynamic response of fiber-reinforced polymer laminate on concrete wall under blast loads
(Springer, 2024-07) Singh, Shamsher Bahadur
Composite laminates are increasingly used for blast-resistant applications in structures owing to the rise of such fanatic activities. For the safe and economical design of blast-resistant structures, it is necessary to study the influence of various laminate characteristics on their dynamic behavior. Here, the influence of design parameters of fiber-reinforced polymer (FRP) laminates in mitigating the dynamic response of a concrete wall when subjected to surface blast loads has been studied. Furthermore, a generalized analytical approach employing classical laminate theory has been presented to analyze the dynamic behavior of a concrete wall applied with the FRP laminate(s) under various explosion-induced load scenarios. It is found that the stacking sequence of the laminae and the number of layers in the laminate decrease the response by about 5% and 15% among the considered configuration, respectively. Moreover, using the FRP laminates reduce the dynamic response of the concrete wall by 18%. Through a detailed parametric study, it has also been observed that the center node displacement of the wall decreases with an increase in standoff distance, an increase in the thickness of the concrete wall, and a decrease in charge weight.
Assessment of carbonation depth under natural and accelerated carbonation conditions
(ICJ, 2016) Singh, Shamsher Bahadur; Bhunia, Dipendu
This paper deals with the effect of accelerated carbonation on mechanical properties and durability of unreinforced concrete. Concrete with water binder ratios of 0.35, 0.50 and 0.65 were cast and kept in accelerated carbonation chamber under controlled conditions for a period of 1 year. Specimens were removed at predefined time intervals and tested for compressive strength, flexural strength, modulus of elasticity, volume of permeable pores and depth of carbonation. The depth of carbonation obtained from the accelerated carbonation conditions are used to predict the carbonation depths under natural concentration of carbon dioxide using Fick’s law and the values are compared to those obtained from a structure 60 years old.
Axial load prediction of circular hybrid double-skin tubular columns using interpretable gradient boosting machine learning models
(Springer, 2026-01) Singh, Shamsher Bahadur; Barai, Sudhir Kumar
This study assesses the predictive performance of three gradient-boosting Machine Learning (ML) models, Gradient Boosting Machine (GBM), eXtreme Gradient Boosting (XGBoost), and Light Gradient Boosting Machine (LightGBM), in axial load prediction of circular FRP-concrete-steel double-skin tubular columns (hybrid DSTCs). Data from 275 specimens were compiled from 22 publications in the literature to train and test ML models. Input variables consist of the height of column (), outer diameter of the FRP tube (), outer thickness of the FRP tube (), diameter of the inner steel tube (), thickness of the inner steel tube (), tensile strength of the outer FRP tube (), yield strength of the inner steel tube (), and compressive strength of concrete (), with the ultimate axial load () serving as the output variable. Performance of all three gradient ML models was evaluated using statistical measures including coefficient of determination (R2), root mean square error (RMSE), mean absolute percentage error (MAPE), and mean absolute error (MAE) for training and testing datasets. Results indicate that the XGBoost model performed better than the other two gradient Models (GBM and LightGBM) with R2 values of 0.97 on the training data and 0.95 on the testing data. Further analysis of the XGBoost model assessed the relative importance of input features on the output feature.
Behavior of Prestressed Concrete Box-Beam Bridges Using CFRP Tendons
(Precast/Prestressed Concrete Institute, 2006) Singh, Shamsher Bahadur
This paperpresents the results of an experimental and analytical study of the flexural response of concrete box beams prestressed with carbon fiber reinforced polymer (CFRP) tendons Diversified Composites Inc. (DCI) for three highway bridge models. Each bridge model comprises two precast concrete box beams pretensioned using DCI tendons. In one of the bridge models, the box beams were also prestressed using 12 unbonded, DCI post-tensioning tendons. in the second bridge model, the box beams were not provided with post-tensioning tendons. The third bridge model comprised box beams provided with 12 unbonded tendons without any force. This study consisted of predicting parameters such as transfer lengths of DCI tendons, ultimate loads, deflections, post-tensioning forces, strains, and energy ratios. This paperaisopresents a comparison of experimental and analytical results. It was observed that the measured transfer lengths of DCI tendons ranged from 25 to 32 times the nominal tendon diameter. The bridge model comprising box beams prestressed using both pretensioning and unbonded post-tensioning tendons resulted in higher load capacity and lower ductility compared with the other two bridge models. The close agreement between experimental and analytical values signifies the accuracy of a strain-controlled approach in analyzing CFRP box beam bridge models.
Bond strength and compressive stress-strain characteristics of brick masonry
(Elsiever, 2017-02) Singh, Shamsher Bahadur
In this study, masonry and its material characteristics such as compressive strength of masonry prisms, bricks, mortars as well as bond strength (i.e., flexural and shear bond strengths) of brick and mortar joint are determined experimentally. The compressive stress-strain curves of brick, mortar, and masonry have been plotted and five control points have been identified on the stress-strain curve of masonry. The control points on the stress-strain curve would be useful for performance based design of masonry. Four types of bricks and three different types of mortars have been used in the experimental study. The compressive strength of masonry and flexural bond strength are determined with a test on five bricks stack bonded prisms. A bond wrench apparatus fabricated as per ASTM standards was used for flexural bond strength test. The shear bond strength of masonry is predicted using masonry triplet. It is observed that the concrete bricks have low flexural as well as shear bond strengths due to less contact area.
Buckling and postbuckling response of hybrid composite plates under uniaxial compressive loading
(Elsiever, 2020-01) Singh, Shamsher Bahadur
Comparative study of accelerated carbonation of plain cement and fly-ash concrete
(Elsiever, 2017-03) Singh, Shamsher Bahadur; Bhunia, Dipendu
Accelerated carbonation of plain cement concrete and concrete with fly-ash replacing cement partially, is discussed in the present paper. Mechanical properties such as compressive strength, flexural strength, modulus of elasticity, durability aspects such as depth of carbonation and porosity of carbonated concrete are studied. To study the influence of water binder ratio on the above-mentioned properties, water-binder ratios of 0.35, 0.50 and 0.65 are used. It is observed that the mechanical properties of carbonated concrete have increased with the duration of carbon dioxide exposure. So did the depth of carbonation, whereas the volume of permeable voids has reduced leading to the decrease in porosity. An expression to predict the depth of carbonation of fly-ash concrete has also been developed.
Comparative study of accelerated carbonation of plain cement and fly-ash concrete
(Elsevier, 2017-03) Singh, Shamsher Bahadur; Bhunia, Dipendu
Accelerated carbonation of plain cement concrete and concrete with fly-ash replacing cement partially, is discussed in the present paper. Mechanical properties such as compressive strength, flexural strength, modulus of elasticity, durability aspects such as depth of carbonation and porosity of carbonated concrete are studied. To study the influence of water binder ratio on the above-mentioned properties, water-binder ratios of 0.35, 0.50 and 0.65 are used. It is observed that the mechanical properties of carbonated concrete have increased with the duration of carbon dioxide exposure. So did the depth of carbonation, whereas the volume of permeable voids has reduced leading to the decrease in porosity. An expression to predict the depth of carbonation of fly-ash concrete has also been developed.
Composite mechanics-based design approach for FRP-strengthened walls
(Taylor & Francis, 2018-08) Singh, Shamsher Bahadur
This study deals with development of a composite mechanics-based design approach for flexural strengthening of masonry walls using different layers of fiber-reinforced polymer (FRP) strips externally bonded and/or near surface mounted (NSM) FRP bars. To verify the developed design approach, experimental study was also conducted on three groups of walls. Six burnt clay brick masonry walls of size 780 × 480 × 230 mm were fabricated. Out of six, four masonry walls are strengthened with combination of longitudinal carbon fiber-reinforced polymer strips and horizontal NSM bars. The flexural responses of these masonry walls were predicted using three-point static loading. To evaluate the effect of using horizontal NSM FRP bars in conjunction with the longitudinal FRP strips on the response of the strengthened wall, an analytical approach using classical lamination theory has been presented. The developed analytical approach shows good agreements with the experimental results in terms of load carrying capacity and mid-span deflection. This analytical approach will help in setting up the design procedure to evaluate the response of a wall that is strengthened with FRP bars/strips provided in multiple layers. A design example has also been provided for easy understanding of the design approach.
Concrete Beams Reinforced with CFRP: Investigating the Shear Performance of Box-Beams Strengthened with Carbon Fiber-Reinforced Polymers
(ACI, 2005-01) Singh, Shamsher Bahadur
Cutout shape and size effects on response of quasi-isotropic composite laminate under uni-axial compression
(Techno Press, 2010-06) Singh, Shamsher Bahadur
Cutouts are often provided in structural and aircraft components for ventilation, for access, inspection, electric lines and fuel lines or sometimes to lighten the structure. This paper addresses the effects of cutout shape (i.e., circular, square, diamond, elliptical-vertical and elliptical-horizontal) and size on buckling and postbuckling response of quasi-isotropic (i.e., (+45/−45/0/90)2s) composite laminate under uni-axial compression. The finite element method is used to carry out the investigation. The formulation is based on first order shear deformation theory and von Karman
Design Approach for CFRP Prestressed Concrete Bridge Beams,
(ACI, 2003) Singh, Shamsher Bahadur
This paper presents a design approach for carbon fiber-reinforced polymer (CFRP) concrete bridge beams prestressed using bonded pretensioning and unbonded post-tensioning tendons arranged in multiple vertically distributed layers along with non-prestressing CFRP rods. Design equations to determine the flexural capacity and to compute the stresses and strains in concrete and tendons are provided. In addition, based on parabolic stress-strain relation for concrete and linear stress-strain relation for tendons, a computer program was developed to compute the overall response of the beam such as deflections, strains, cracking loads, and post-tensioning forces. The design equations and the accuracy of the nonlinear computer program were validated by comparing the analytical results with experimental results from a full-scale double-T (DT) test beam. The difference in the analytical and experimental values of the ultimate moment capacity of the DT-test beam is negligible, whereas the corresponding difference in the ultimate forces in unbonded externally draped post-tensioning strands is approxi- mately 4.1%. A detailed parametric study was conducted to examine the effect of the reinforcement ratio and the level of pre- stressing forces on the deflections and ultimate load-carrying capacity of the full-scale DT-beam. It is observed that the reinforce- ment ratio and the level of prestressing have significant effect on the moment-carrying capacity and ultimate load deflection of the beam. The combination of bonded and unbonded prestressing levels (0.3 to 0.6) can significantly increase the ultimate moment capacity of an over-reinforced beam.
Design of concrete beams reinforced with FRP bars
(Springer, 2024-04) Singh, Shamsher Bahadur
Design of RC beams with longitudinal reinforcement made of steel bars has adopted the philosophy of Under-Reinforced Design. But, Concrete Beams with FRP longitudinal bars need a reconsideration of this philosophy. The large strength of FRP bars and low strength of concrete obviates Over-Reinforced Design. By suitably increasing the amount of FRP longitudinal bars, it is possible to enhance the deformability of the FRP-reinforced beams. While Limit State Method of design will be applicable still, the partial safety factors on loads and on materials need to be adopted after due experimental studies.
Design Oriented Stress-Strain Models for Engineered Cementitious Composites
(DST, 2016) Singh, Shamsher Bahadur
Engineered Cementitious Composite (ECC) is known for multiple cracking and strain hardening property when loaded in tension. To incorporate this superior property in the design of structural elements, it is mandatory to develop design oriented stress-strain models considering the tensile strain hardening property. In the present study, stress-strain models are developed for both tension and compression using the empirical values available in literature. An analytical study has been conducted on the flexural response of Fiber Reinforced Polymer (FRP) reinforced ECC beams to understand the robustness of the developed stress-strain models. For this purpose, a special purpose non-linear computer program is developed based on force equilibrium and strain compatibility conditions to predict the ultimate load and deflection. The accuracy of the nonlinear computer program is validated by comparing the analytical results with experimental results available in literature which is found to be in close agreement. Hence, it is inferred that the developed stress-strain models can be used for various design purposes.
Design, Construction, and Failure Aspects of World Trade Center Towers
(CECR, 2013) Singh, Shamsher Bahadur
Due to the advent of innovative construction materials and technology, many high-rise buildings are being erected worldwide. These structures are advantageous from the point of view of low plinth area requirement, high occupancy, housing, communication and control towers, and aesthetic view. High-rise structures have also become attractive tourist places these days and in fact, they symbolize how developed is the city and the whole country. They have also become the real pride of a nation.