shear key

Design of Shear Key in Base Plate as per IS Code

DESIGN OF SHEAR KEY     as per IS800 and concrete checks are IS450-2000    

Base plate design as per IS800 codal provisions, Shear key is provided to increase the resistance to sliding. The shear key is generally an extension of the vertical stem and extends below the bottom of the base to help reducing the thickness of the anchor bolts by absorbing the shear force.                                                                                                      

            Base Plate length                                                          =          650       mm                 

            Base Plate Width                                                          =          650       mm                 

          Maximum Horizontal shear                                F          =          53.000  kN        Ref: Annexure G.5              

            Characteristic comp. strength                           fck        =          30        N/mm²  IS:456-2000 Table 2                

            Allowable bearing stress                                   sb         =          0.25fck             IS:456-2000 cl. 34.4                

                                                                                                   =          7.5       N/mm2                        

            Bearing Stress factor                                                      =          1.25                                         

            Depth required                                                  D            =          F/(1.25*sb*L)                                       

                                                                                                     =          11        mm                             

            Provide shear key depth below grout                                         100       mm                             

                                                                                    L                =          500

            Bearing pressure on the plate                            p             =          F/(D*L)                                    

                                                                                                       =          1.06      N/mm2                        

                                                                                                                       

            The shear key is designed as a plate is fixed on two sides and free on other two sides.                                                                                                           

                                                                                                                       

                                                                                    D            =          150

            Max. Bending moment                                                   =          1.06 x 100 x (100/2+50)                                                

                                                                                                  =          10600   N.mm                                      

            Bending Stress factor                                                    =          1.33                                                     

            Allowable bending stress                                               =          185*1.33                                                          

                                                                                                   =          246.05  N/mm2                                    

            Thickness of shear key                                     t             =          sqrt(6M/sbc)                                                    

                                                                                                    =          16.1      mm                                         

            Thickness provided                                                          =          25        mm      OK                              

            Provide shear key as 500 x 150 x 25mm                                                                                                           

                                                                                                                        L/C:      115      

            Fz – Direction                                                                                        Node:   64

           

            Maximum Horizontal shear                                F          =          51.500  kN        Ref: Annexure A2                

 

            Characteristic comp. strength                           fck          =          30        N/mm²  IS:456-2000 Table 2                

            Allowable bearing stress                                   sb            =          0.25fck             IS:456-2000 cl. 34.4                

                                                                                                      =          7.5       N/mm2                        

            Bearing Stress factor                                                         =          1.25                                         

            Depth required                                                  D              =          F/(1.25*sb*L)                                       

                                                                                                       =          10.99    mm                             

            Provide shear key depth below grout                                         100       mm                             

            Bearing pressure on the plate                            p              =          F/(D*L)                                    

                                                                                                        =          1.0       N/mm2                        

                                                                                                                       

            The shear key is designed as a plate is fixed on two sides and free on other two sides.                                                                                                           

                                                                                    L          =          500      

                                                                                                                       

                                                                                                                       

                                                                                    D            =          150

            Max. Bending moment                                                  =          1.03 x 100 x (100/2+50)                                                

                                                                                                   =          10300   N.mm                                      

                                                                                                                       

            Bending Stress factor                                                    =          1.33                                                     

            Allowable bending stress                                               =          0.66*230*1.33                                                  

                                                                                                   =          201.894            N/mm2                                    

                                                                                                                       

            Thickness of shear key                                     t           =          sqrt(6M/sbc)                                                    

                                                                                                  =          17.5      mm                                         

            Thickness provided                                                       =          25        mm      OK                              

            Provide shear key as 500 x 150 x 25mm

breakout check

BREAKOUT CHECK FOR PEDESTAL                                                                                                            

           Check for shear break-out strength                                                                                                      

            FX direction                                                                                                     

            For M30 tc,max                                                  =         2.2       N/mm2      IS:456, Table 24 

            Maximum  Horizontal Shear                   Fx        =         100.000            kN       

            Actual shear stress                                             =         100*1000/(375*750)                                         

                                                                                       =         0.36      N/mm2        Assuming minimum p of 0.15%                                                                                                

            For M30 tc,perm                                                 =         0.2       N/mm2       IS:456, Table 23                   

             Design Shear Vs                                                =         (0.36-0.2)*(375*750)                                        

                                                                                         =         45000.00          N                                 

            Spacing assumed in pedsestal height (Sv)         =         200       mm      `                      

            Effective depth (d)                                               =         375       mm                             

            No. of legs  assumed                                       
=         10                                           

                                                                        Vs        =         ssv . Asv .d                                         

                                                                                                            Sv                                           

            Dia of leg required                                            =            SQRT(45000*200/(230*10*PI()*0.25*375))                                            

                                                                                     =         3.64      mm                             

 

            Dia of leg provided                                            =         10        mm

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