Browsing by Author "Kumar, Manoj"

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Analytical modeling of damping
(Indian Concrete Journal, 2014) Muthukumar, G .; Kumar, Manoj
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 small failure and catastrophic collapse, thus highlighting the importance of damping in a dynamic analysis of structures. Unlike mass and stiffness matrices, damping cannot be determined analytically thus bringing dynamic analysis in a state of uncertainty. Various representations of damping have evolved over the period of years which are tailor-made to specific problems. It has been generally accepted that there is no single universally accepted method for the representation of damping in an analytical manner. In this paper, an attempt has been made in reviewing the various damping models that are currently in practice.
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.
Behaviour of shear wall with openings – A review
(Indian Concrete Journal, 2017) Muthukumar, G .; Kumar, Manoj
Design strategies for multiplayer gaming on embedded platforms using wireless networks
(BITS Pilani, Pilani Campus, 2014-06-23) Kumar, Manoj
Effect of imperfection on behaviour of axial loaded square and rectangular concrete-filled steel tubular columns
(Elsevier, 2024-02) Kumar, Manoj
Axial compressive strength of Concrete Filled Steel Tubular (CFST) columns is significantly improved owing to lateral confinement and the interaction between steel tube and concrete core. Occasionally there exists an initial gap between the concrete core and steel tube which may occur due to improper compaction, shrinkage in concrete, lack of curing of concrete core, etc., consequently, the compressive strength of the column is reduced. Present study shows that the presence of a gap between the concrete core and steel tube reduces the axial strength of CFST column to some extent; however, it results in an enormous fall in the ductility of column. A total of 22 specimens, including 2 hollow steel tube subjected to axial compressive loading, were tested. The main parameters of these tests were the circumferential gap. The influence of gap on the failure mode and ultimate strength of the CFST specimens were investigated. The results show close agreement between calculated and experimental results in terms of load-deformation response and ultimate strength. The behavior of CFST columns with a gap is analyzed, to investigate the impact of different parameters on ultimate strength. A maximum limit of 1.4 to 5.9 gap ratio is proposed, and a simplified formula is suggested to estimate the effect of a gap on ultimate strength
Effect of Overloading on Shear Lag Effect in RC Box-Girder Bridges
(ICJ, 2016-08) Kumar, Manoj
Effect of Skewness on Live Load Distribution in Webs of Concrete Box-Girder Bridges
(IJTIMES, 2019) Kumar, Manoj
The aim of the present paper is to study the effect of skewness on distribution of live load among the webs of the horizontally curved concrete box-girder bridges. In this paper, a 27.4 m long simply supported RC box-girder bridge has been considered to investigate the influence of skewness on box-girder with various curvatures. To this end, the central curvature angle of the bridge has been varied from 0° to 48° at an interval of 12° and the skew angle is swept from 0° to 50° at an interval of 10°. Using the three-dimensional Finite element analysis software CsiBridge, maximum vertical deflection under the webs of box-girder have been determined due to the IRC specified Class-70R tracked vehicular LL moving over the bridge at constant speed at maximum eccentricity specified by Indian Road Congress. Assuming the linear elastic behavior of the bridge, the live load has been distributed among the webs in the proportion of vertical deflections. The study revealed that the live load distribution among the webs is significantly affected by the skewness in conjunction with curvature. The results indicate that with increase in skewness, live load transferred to inner web decreases for almost all the curvature angles
Experimental and numerical investigation on behavior of circular concrete-filled double-skinned steel tubular short columns under eccentric load
(Springer, 2022-07) Kumar, Manoj
This article describes experimental and numerical analyses of eccentrically loaded over the axially loaded circular concrete-filled double-skinned steel tubular (CFDST) short columns. Tests on circular CFDST short columns under eccentric and concentric loading were conducted to assess their responses to the frequent intensity of 5–30 mm at the interval of each 5 mm eccentric loading conditions with constant cross-sectional proportions and width-to-thickness ratios of the outside and internal tubes. The non-linear finite-element analysis of circular CFDST short columns of eccentrically loaded over the axially loaded was performed using the ABAQUS to predict the structural behavior and compare the concentric loading capacity over the various eccentric loading conditions. The comparison outcomes show that the axial compressive strength of the circular CDFST short columns was 2.38–32.86%, lesser than the concentrically loaded short column with the inner circular section. Also, the influence of computer simulation employed is more efficient in forecasting the experimentally examined performance of circular CFDST stub columns.
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.
Failure criteria of concrete- A review
(TechnoPress, 2014-11) Muthukumar, G .; Kumar, Manoj
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.
Flexural response of skew-curved concrete box-girder bridges
(Elsiever, 2018-05-15) Kumar, Manoj
The flexural response of the box-girder bridges, having curvature and skewness together referred as skew-curved bridges, cannot be predicted by simply superimposing the individual effect of skewness and curvature due to the coupling of these effects. Moreover, the complexity of such thin-walled box-girder bridges increases under eccentric vehicular loads causing additional torsional and warping stresses in the box-sections. The present study focuses on predicting the flexural response of simply supported single cell skew-curved concrete box-girder bridges. In order to investigate the effect of curvature and skewness, the central curvature angle has been varied from 0° to 48° at an interval of 12° while the skew angle is swept from 0° to 50° at an interval of 10°. Three-dimensional analysis models of the bridges are created using CSiBridge and a finite element analysis has been carried out for gravity loads and Indian Road Congress (IRC) specified Class 70R tracked vehicular Live Load (LL) plying at a minimum specified clearance from the kerb. The parametric study results indicate that the flexural response of the inner girder (web) becomes more pronounced in case of skew-curved bridges. In general, it has been observed that presence of skewness in highly curved bridges significantly improves the flexural response of the bridge. Furthermore, the critical position of LL producing the absolute maximum longitudinal moment as well as the location of the critical section for moment has been found significantly affected by skewness and curvature. These critical positions have been presented in the framework of newly developed ‘skew-curve’ coordinate system for systematic representation.
Influence of Distributed Dead Loads on Vehicle Position for Maximum Moment in Simply Supported Bridges
(Springer, 2017-05-08) Kumar, Manoj
Usually, the design moments in the simply supported bridges are obtained as the sum of moments due to dead loads and live load where the live load moments are calculated using the rolling load concept neglecting the effect of dead loads. For the simply supported bridges, uniformly distributed dead load produces maximum moment at mid-span while the absolute maximum bending moment due to multi-axel vehicles occur under a wheel which usually do not lie at mid-span. Since, the location of absolute maximum bending moment due to multi-axel vehicle do not coincide with the location of maximum moment due to dead loads occurring at mid-span, the design moment may not be obtained by simply superimposing the effect of dead load and live load. Moreover, in case of Class-A and Class-70R wheeled vehicular live loads, which consists of several axels, the number of axels to be considered over the bridge of given span and their location is tedious to find out and needs several trials. The aim of the present study is to find the number of wheels for Class-A and Class-70R wheeled vehicles and their precise location to produce absolute maximum moment in the bridge considering the effect of dead loads and impact factor. Finally, in order to enable the designers, the design moments due to Class-70R wheeled and Class-A loading have been presented in tabular form for the spans from 10 to 50 m.
Influence of Opening Locations on the Structural Response of Shear Wall
(Hindawi Publishing Corporation, 2014) Muthukumar, G .; Kumar, Manoj
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 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 Openings on the Structural Response of Shear Wall
(Hindawi Publishing Corporation, 2014) Muthukumar, G .; Kumar, Manoj
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.
Investigation on circular and octagonal concrete-filled double skinned steel tubular short columns under axial compression
(Techno-Press, 2022-07) Kumar, Manoj
This paper describes the experimental and numerical investigation on circular and octagonal CFDST short columns under concentric loading to study their responses to various internal circular steel tube sizes by the constant cross-sectional dimensions of the external circular and octagonal steel tube. The non-linear finite element analysis of circular and octagonal CFDST columns was executed using the ABAQUS to forecast and compare the axial behavior influenced by the various sizes of internal circular steel tubes. The study shows that the axial compressive strength and ductility of circular and octagonal CFDST columns were significantly influenced by inner steel tubes with the strengths of constituent materials.
Nonlinear finite element dynamic analysis of squat shear wall with openings
(Springer, 2013-11-11) Kumar, Manoj
Shear wall has been considered as a major lateral load-resisting element inmultistoried building located in wind- or earthquake-prone zone. The behavior ofshear wall under various loading conditions has been the subject of intenseresearch for the last few decades. The behavior of shear walls without openingsis completely well understood and well documented in literature. The use ofsquat shear wall has been found in many low-rise buildings. On the other hand,squat shear walls may also be provided with openings due to the functionalrequirement such as placement of doors/windows in the building. The size andlocation of the opening play a significant role in the response of the shearwall. Even though it is intuitively known that the size of opening hassignificant effects on the behavior of a shear wall, it is desirable to know thelimiting size of opening in the shear wall, beyond which the shear walls mayfail or become unserviceable, especially when subjected to severe earthquakeground motions. In this study, the materially nonlinear dynamic response of theshear wall, with and without openings for different damping ratios, subjected toEL Centro earthquake has been captured. For dynamic analysis, constantacceleration Newmark β method of direct time integration has been used.From the study, it was observed that the presence of opening results in severedisplacements and stresses on the shear wall and also results in stressconcentration near the opening tip. Hence, the presence of damping has beenconsidered to be vital for large opening under severe dynamic loadingconditions.
Response of perforated H-pile subjected to coupled lateral displacement history and axial loading
(Taylor & Francis, 2022-11) Kumar, Manoj
The substructure of an integral abutment bridge is designed to accommodate the lateral demand induced by the expansion and contraction of the bridge deck. The assembly of H-piles oriented about their weak axis of bending and aligned in a single row with a rigid connection to the abutment is most preferred for supporting the integral abutment bridges. The weak axis orientation of H-pile allows for higher displacement capacity, thus accommodating the cyclic thermal demand induced by a superstructure. The hysteretic response of H-piles is suggestive of the early onset of the plastic hinge formation, which helps in accommodating the cyclic demand. The H-piles in the integral abutment bridge experience low cycle fatigue induced by cyclic thermal variations, resulting in the buckling of flanges at the critical zone. This study assesses the impact of perforation made on H-pile flanges at the critical buckling zone. In this study, six unique geometries of perforations are modelled and analysed using combined nonlinear kinematic and isotropic hardening formulation. The hysteretic response of the perforated H-pile models has been compared with an unperforated model to assess the proposed perforation geometry's impact on the H-pile's hysteretic response.
Shape effect on axially loaded CFDST columns
(Techno-Press, 2022-06) Kumar, Manoj
Concrete-filled double skinned steel tubular (CFDST) columns have been used to construct modern structures such as tall buildings and bridges as well as infrastructures as they provide better, lesser weight, and greater stiffness in structural performance than conventional reinforced concrete or steel members. Different shapes of CFDST columns may be needed to satisfy the architectural and aesthetic criteria. In the study, three-dimensional FE simulations of circular and elliptical CFDST columns under axial compression were developed and verified through the experimental test data from the perspectives of full load-displacement histories, ultimate axial strengths, and failure modes. The verified FE models were used to investigate and compare the structural performance of CFDST columns with circular and elliptical cross-section shapes by evaluating the overall load-deformation curves, interaction stress-deformation responses, and composite actions of the column. At last, the accuracy of available design models in predicting the ultimate axial strengths of CFST columns were investigated. Research results showed that circular and elliptical CFDST column behaviors were generally similar. The overall structural performance of circular CFDST columns was relatively improved compared to the elliptical CFDST column.