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Devdas Menon
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Devdas Menon
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Devdas Menon
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Menon, Devdas
Menon, D.
Devdas, Menon
Menons, Devdas
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6 results
Now showing 1 - 6 of 6
- PublicationDevelopment of strut-and-tie models for RC bridge pier caps subjected to asymmetric loading(01-01-2016)
;Geevar, InduReinforced concrete (RC) bridge pier caps are subjected to concentrated loads from the superstructure. These are deep members where strain distribution is non-linear and traditional flexural theory cannot be used. Strut-and-tie method can be used to design and detail such regions which idealises the pier cap domain into struts and ties capable of transmitting the loads to the pier. The loads on pier caps can be asymmetric due the effect of live loads, unequal spans and possible curvature of the superstructure. This paper attempts to develop strut-and-tie models for symmetric pier caps subject to asymmetric loading. The possible strut and tie models (STM) for load cases with one side subjected to a heavier load with respect to the other are presented. The ratio between heavier and lighter load is considered as a parameter in this study. The optimised strut and tie model is chosen from the possible models for a particular load case based on minimum tension load path (sum of product of force and corresponding length of the tension members). A solution algorithm is presented for the development of strut and tie models. - PublicationDevelopment of strut-and-tie models for rc bridge pier caps subjected to asymmetric loading(01-01-2016)
;Geevar, InduReinforced concrete (RC) bridge pier caps are subjected to concentrated loads from the superstructure. These are deep members where strain distribution is non-linear and traditional flexural theory cannot be used. Strut-and-tie method can be used to design and detail such regions which idealises the pier cap domain into struts and ties capable of transmitting the loads to the pier. The loads on pier caps can be asymmetric due the effect of live loads, unequal spans and possible curvature of the superstructure. This paper attempts to develop strut-and-tie models for symmetric pier caps subject to asymmetric loading. The possible strut and tie models (STM) for load cases with one side subjected to a heavier load with respect to the other are presented. The ratio between heavier and lighter load is considered as a parameter in this study. The optimised strut and tie model is chosen from the possible models for a particular load case based on minimum tension load path (sum of product of force and corresponding length of the tension members). A solution algorithm is presented for the development of strut and tie models. - PublicationAssessment of Strut-and-Tie Methods to Estimate Ultimate Strength of RC Deep Beams(01-01-2017)
;Adrija, D. ;Geevar, Indu; Reinforced concrete (RC) deep beams are structural members characterized by relatively small shear span to depth (a/d) ratios. Sectional analysis as well as design procedures are not valid for these members due to the complex interaction of flexure and shear. The strut-and-tie method (STM) has been widely accepted and used as a rational approach for the design of such disturbed regions (D regions) of reinforced concrete members, where traditional flexure theory cannot be used. The flow of stress is idealized as a truss consisting of compressive struts (concrete) and tension ties (reinforcing steel) transmitting the loads to the supports. Usually, STM considers only equilibrium. Hence, there is no unique solution for a given system, as one can find more than a single truss geometry admissible for a given force field. Therefore, the model which gives the maximum capacity can be considered as the most appropriate one. This paper attempts to predict the ultimate strength of deep beams failing in diagonal compression as well as tension, from the experimental database available in literature based on STM. A modified approach has been used, considering the crushing and splitting failures of the diagonal strut separately. Crushing failure of the diagonal strut has been predicted using a plastic Strut-and-tie model with varying compression zone depth. A localized STM has been considered to predict the splitting failure of the diagonal strut. - PublicationStrength of reinforced concrete pier caps-experimental validation of strut-and-tie method(01-01-2019)
;Geevar, InduThe strut-and-tie method (STM) is commonly used to design reinforced concrete (RC) pier caps, where the traditional methods of shear and flexural design cannot be used due to nonlinear strain distribution. This paper presents experimental studies on scaleddown pier cap specimens subject to four concentrated loads, to study the influence of various parameters and the applicability of STM. The STM prescribed by ACI 318 and AASHTO are found to give reasonably conservative results only when the beneficial effect of triaxial confinement near the bearing node is invoked; otherwise, the predictions are overly conservative. Variations in bearing plate size, distributed reinforcement, and loading eccentricity did not have much influence on the load capacity, but distributed reinforcement was seen to be beneficial in limiting crack widths. The formation of the assumed STM is validated using strain measurements in concrete and steel, and it is observed that this develops only after significant cracking. - PublicationGeneration of P-M interaction design charts for RC shear walls(01-07-2019)
;Balakrishnan, Bijily ;Geevar, Indu ;Jithin, K. V.Reinforced concrete (RC) shear walls resist lateral loads in a building due to wind and earthquake, in addition to gravity loads. Each rectangular shear wall segment (sometimes provided with ‘boundary elements’ at the ends) is required to be designed to resist axial compression (P) combined with in-plane bending moment (M). This paper provides closed-form expressions for generating the full P-M interaction curve for the design and analysis of shear walls with and without boundary elements, which has been validated with SAP. It also gives normalised load/moment expressions for generating design charts, similar to SP 16 charts for RC columns. The simplified method given in IS 13920 is applicable only for rectangular shear walls with uniformly distributed main reinforcements. The proposed method provides a more accurate and economical solution than the simplified method given in IS 13920. - PublicationUnexpected cracking in a rc pier cap - A case study(01-01-2018)
;Geevar, Indu ;Prasad, Meher; Adrija, D.This paper presents an investigation on structural cracking observed in a reinforced concrete (RC) pier cap supporting a prestressed concrete box girder of 13m span, with a carriage way width of 20m. The pier cap is designed to carry the heavy concentrated loads transmitted to the pier through elastomeric bearings. Unexpected vertical cracks were observed at service loads on the sides directly under the bearings. A site visit revealed that the elastomeric bearings were compressed on one side with loss of contact on the other. The crack width measurements showed a crack width as high as 1mm at some locations, where the cover provided was found to be 100 mm, which is more than the proposed cover of 50 mm. A detailed analysis using nonlinear finite element analysis (NLFEA) was performed to understand the causes of these cracks using two models: One with full contact of the bearings and the other with half contact. The complete crack pattern was obtained from NLFEA which showed cracking at a similar location as that at the site. The cracking occurred at a lower load in the model with half contact at bearings. This clearly established the reason for cracking as the reduced contact area at the bearings. The wide cracks were perhaps due to the unexpected high cover at the corner location. The safety of the structure at ultimate loads was also checked using NLFEA and strut-and-tie method, and is seen that the structure is safe at ultimate loads.