International Research Journal of Engineering and Technology (IRJET) Volume: 04 Issue: 02 | Feb -2017
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e-ISSN: 2395 -0056 p-ISSN: 2395-0072
Prediction of Ultimate Shear Strength of Moderate Deep Concrete Beam Including Size Effect Suhag Patel1, Vikas Khoda2, H. K. Patel3, Dr. V. R. Patel4, Dr. I. I. Pandya5 Students, Faculty of Technology and Engineering. The M.S.University, Vadodara professor, Applied Mechanics and Structural Engineering Department, Faculty of Technology and Engineering. The M.S.University, Vadodara 5 Associate professor, Applied Mechanics and Structural Engineering Department, Faculty of Technology and Engineering. The M.S.University, Vadodara
3, 4 Assistant
1, 2 PG
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Abstract - This paper investigate the effects of beam
criteria are classified as moderate deep beam. ACI-ASCE committee 426 classifies a beam with a shear span-to-depth ratio a/D less than 1.0 as a deep beam and a beam with a/D exceeding 2.5 as an ordinary shallow beam. Any beam in between these two limits is categorized as a moderate deep beam. As per Indian Standard Code IS 456: 2000, A beam shall be deemed deep beam when L/D ratio less than (1) 2.0 for simply supported beam (2) 2.5 for continuous beam. Shallow beams are characterized by linear strain distribution and most of the applied load is transferred through a fairly uniform compression field. It can be analysed generally by pure bending theory based on assumption that plane sections normal to the axis remain plane after bending. The stress distribution across the section is almost linear. Shallow beams are assumed as one-dimensional linear elements so they resist transverse loading mainly by bending and shear or say mainly by developing flexure and shear stresses. There is a negligible effect of normal pressure on stress distribution. Generally shallow beams fail under pure flexure failure as it has very low flexure strength as compared to its shear strength. Moderate deep beams differ from shallow beams considerably. There is a significant effect of normal pressure on stress distribution. Flexure strength is comparable to shear strength or almost equal in case of moderate deep beams and hence failure of such type of beams is flexureshear failure. This type of beams is taken as a transition between normal and deep beams regarding to all its properties related to its structural behaviour under applied loading. As the beam become shorter or deeper the stress distribution becomes non-linear with the tensile stresses concentrating toward the bottom of the beam. The stresses at mid span deviate more and more from those predicted by the simple bending theory. Deep beams behave entirely different from normal beams. Normal pressure has greater effect on stress distribution and hence stress distribution no longer remains linear.
parameters like effective depth(d) and compressive strength (fck) on ultimate shear strength of moderate deep concrete beam. Strain distribution in moderate deep concrete beam is not remaining linier. So, prediction of ultimate shear strength of moderate deep concrete beam is less accurate and complex. Many empirical equations and theories are available to predict ultimate shear strength of moderate deep concrete beam. Aim of this research is modification of equation (for ultimate load of concrete beam fails in shear without stirrups) given by Dr. S. N. Patel and Dr. S. K. Damle. Effect of effective depth (d) of concrete beam and compressive strength (f ck) is incorporated in terms of size effect factor in above mentioned equation. Also for finding ultimate load of concrete beam fails in shear with stirrups, an extra term is added in above mentioned equation to incorporate effect of stirrups in ultimate shear strength. Modified equation gives good agreement with experiment test results of previous experiments. Key Words: Ultimate shear strength, Moderate deep concrete beam, size effect, IS: 456-2000, Ultimate load.
1. INTRODUCTION Beam is one of the major structural element generally subjected to transverse loading. Many research works have been carried out and reported so far to predict the behaviour or response of beam against applied loading. Due to various types of materials, arrangement of loading, support condition and various types of site and environmental condition, research work is still needed in this vast field. Especially considering the beam mainly fail in shear. There is still lack of knowledge about deep understanding of complete structural response of beam which fails in shear. Generally beam can be classified according to their span to depth ratio and shear span to depth ratio. Normal beam has depth very less compared to its length, while deep beam has its depth equal or less compared to its depth. Moderate deep beam falls in between normal and deep beam. Generally beams classified with effective span-to-depth ratio L/D less than 2.5 as deep beam and ratio L/D greater than 6.0 as shallow beam. Beams falls between above two
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