International Journal of Scientific & Engineering Research, Volume 4, Issue 6, June-2013 1331 ISSN 2229-5518 IJSER © 2013 http://www.ijser.org Comparative study for shear design using IRC 112:2011 & IRC 21:2000 B.H.Solanki & Prof.M.D.Vakil ABSTRACT Current practice in world for shear design many various practice is going on, As Shear is more critical force than other actions on bridge’s members ,new code IRC 112:2011 has improved in shear criteria compare to old IRC 21:2000.This paper presents shear strength, steel required for shear & shear resisting capacity of the member without shear reinforcement for LSM & WSM. Also this paper will shows which combinations of fy grade of steel & fck grade of concrete gives more shear strength so member requires minimum or no shear reinforcement. KEY WORDS VEd applied shear force, VRdc shear resisting without shear reinforcement, VRds shear resisting capacity with shear reinforcement. INTRODUCTION To design any member for shear, one has to derive shear force very accurately & model that member for shear so that it will act as assumed. IRC 112:2011 changes shear design procedure quite similar to old procedure but equations for each step changed. In old code IRC 21:2000 , shear resisting capacity of member is calculated with amount of longitudinal reinforcement & grade of concrete fck, than difference is check whether applied shear is more than without shear reinforcement or not if it is than it is provided for excessive shear force or if not required than minimum shear reinforcement is provided, but there is no clause for maximum shear reinforcement criteria. In IRC 112:2011 same procedure is followed but VRd,max that is shear strength of the member with shear reinforcement by allowing up to crushing of concrete are different for inclined & vertical type.For box & T section special provisions are given, in short compare to IRC 21:2000 new code IRC 112:2011 has improved a lot in shear design. BASIS OF DESIGN Following table shows some major changes in new code, Procedure adopted for calculation of shear steel are same but change in shear resistance are very large. PARAMETER IRC 21:2006 IRC 112:2011 Analysis Not specified Specified Min steel Asw same for both type inclined & vertical. Different for inclined & vertical Max. steel Asw,max Not specified Specified for both inclined & vertical. Shear steel design for T- section flange Not specified Specified Min steel depends on Fy grade of steel only Takes ratio of fy & fck METHOD Tha basic procedure in any reinforced concrete structure for shear is as follows, 1.Analyze structure & derive shear force for your members VkN 2. calculate shear resisting capacity of member with used grade of concrete fck & amount of longitudinal reinforcement. Vc kN 3.Check V-Vc,if it’s >0 than provide shear reinforcement for that much shear force. 4.If it’s <0 than section doesn’t need any design shear reinforcement but provide minimum as per codal provision. Based on above simple steps charts are carried out which shows shear comparison for WSM & LSM, i.e IRC 21 & IRC 112. LIMIT STATE METHOD, IRC 112:2011 Equations used are, 1. Clause 10.3.2,page 88  = [0.12(80 ∗  ∗ ) 0.33 + 0.15 ∗ ] ∗  ∗  2. Clause 10..3.3.2, page-90 for vertical shear reinforcement VRds = Asw/s *z*fywd*cot θ VRd,max = αcw*bw*z*v1*fcd/(cot θ + tan θ ) Asw,max * fywd/bw*s ≤ 0.5*αcw*v1*fcd 3. Clause 10.3.3.3,page 91,for Inclined shear reinforcement. VRds = Asw/s *z*fywd*(cot θ+ cot αl) VRd,max = αcw*bw*z*v1*fcd*(cot θ +cot αl)/(1+ cot 2 θ) Asw,max*fywd / bw*s ≤ 0.5* αcw*v1*fcd / sin αl l 4. Clause 10.3.3.5,page-95, Min. reinforcement ratio IJSER