For cantilevered and gravity walls vertical expansion joint spacing shall be a maximum of 60 feet on centers.
Movement joints in concrete retaining walls.
Greater distances between movement joints 9 m and sometimes longer are possible in aggregate concrete blockwork walls depending on the location and block type.
In concrete walls the movement joints should normally be placed at a maximum spacing of 7 5m.
The hight shear force is applied at the horizontal construction joints located at the lower level.
The weaker the mix the increased ability to accommodate movement.
1 3 movement and restraint in concrete structures restrained movement is a major cause of cracking in con crete structures.
Internal or external restraint can develop tensile stresses in a concrete member and the tensile strength or strain capacity can be exceeded.
6 to 9m factors influencing spacing of joints are.
In reinforced walls and 6m in unreinforced walls.
Contraction joints are usually about 0 25 inches wide and about 1 2 to 3 4 inch deep and are provided at intervals of not exceeding 30 feet.
There is a special check to be done at the construction joints when larger retaining walls or structures having very high lateral loads are designed.
Use of bedjoint reinforcement and moisture content of blocks when laid.
The friction of the concrete is the key factor that limits the movement.
4 recommends a contraction joint spacing of 30 times the wall thickness or 20 feet for an 8 inch thick wall 30 8 240 inches 20 feet.
These are vertical joints or grooves formed or cut into the wall that allows the concrete to shrink without noticeable harm.
Typical movement joint spacing for unreinforced concrete masonry panels.
Expansion joints should normally be provided at a spacing of not more than 30m between successive expansion joints or between the end of the structure and the next expansion joint.
Some designers recommend re ducing joint spacings by about 20 in walls with frequent openings such as doors and windows.
Precast concrete cantilever wall expansion joints shall be in accordance with the standard specifications section 6 11 3 3.
They are essentially vertical planes of weakness built into the wall to reduce restraint and permit longitudinal movement due to anticipated shrinkage and are located where stress concentrations may occur.
Tial basement walls and the national ready mixed concrete association ref.
