Dowel bars, tie bars and their design

Dowel bars, tie bars and their design

1. Dowel Bars, Tie Bars and Their Design Pavement Design Bhavya S. Jaiswal Btech civil, Mtech Transportation Engineering

2. Dowel bars and its design 2 Placed across the transverse joints at mid depth of the slab Reduces faulting and also prevents corner cracking Transfers load from one to another slab but not prevent the joints from opening. They are generally round, smooth, epoxy coated bars. Prepared by: Bhavya S. Jaiswal

3. Design of the dowel bars 3 Apply the following equation to find length of the dowel bars , Ld   Where, Ld = length of the bar d = diameter of the bar = joint width Ff = permissible stress in bending Fb = permissible stress in bearing   Make a relation with the above equation and put trial value of Ld as 45cm and find the Ld Length of the Dowel bar = Ld + and provide a round about length as LDprovided   Prepared by: Bhavya S. Jaiswal

4. Design of the dowel bars 4 Find the load transfer capacity by the equations…   Fs = permissible stress in Shear Prepared by: Bhavya S. Jaiswal

5. Design of the dowel bars 5 Take load transfer capacity as 40% if not given and find , , take which ever is maximum as a desire capacity and   P= design wheel load Find the effective load transfer as 1.8 where, = radius of relative stiffness   Prepared by: Bhavya S. Jaiswal

6. Design of the dowel bars 6 Actual capacity   Assume 35cm spacing and find the actual capacity… Check if Actual capacity > Required capacity if it is not greater than reduce the spacing and check it again Prepared by: Bhavya S. Jaiswal

7. Tie bars and design of tie bar 7 Placed across longitudinal joints at mid depth of the pavement. It reduces the transverse cracking. Prevents lane separation and also at the same time prevents differential deflection in the pavement. Generally, such bars are made up of deformed epoxy coated steel. Prepared by: Bhavya S. Jaiswal

8. Design of the Tie bars 8 Find the length of the tie bar using the following equation…   Where, = working tensile stress (17.50) = diameter of the bar (max 20mm) = bond strength (24.6)   Find out the spacing between the bars…   Prepared by: Bhavya S. Jaiswal

9. Design of the Tie bars 9 Where ,   Where, w = unit weight of the concrete (2400kg/ ) F = friction (1.5) B = width of the slab (per lane) h = thickness of the slab = 17.5kg/   Prepared by: Bhavya S. Jaiswal

10. References 10 IRC-58:2012 The constructor : https://theconstructor.org/practical-guide/tie-bar-constructions/37378/ Engineerwing : https://www.engineerwing.com/2017/05/types-of-concrete-pavement-uses.html Dowel bars : pavement interactive; https://pavementinteractive.org/reference-desk/pavement-types-and-history/pavement-types/dowel-bar/ Prepared by: Bhavya S. Jaiswal