Bands are reinforced concrete or reinforced brick runner provided in the load bearing wall to tie them together and to impart horizontal bending strength in them.
RCC bands or reinforced brick runner are the important horizontal member of load bearing wall masonry construction which resists forces and ties wall together. They integrate masonry wall into the stronger unit. There are five types of band namely gable band, roof band, lintel band, sill band, and plinth band, named after their location in the building.
A gable band is a horizontal member which is placed at the top of the ridge of the sloping slab to support the ends of the rafters and transferring loads to posts or gable end walls.
A roof band is a load bearing member of a roof at roof level. Sometimes roof band is not required because the roof slab of load bearing wall masonry also plays the role of a band. Roof beams are generally provided in the building with flat timber or CGI sheet roof.
A lintel band is a horizontal member which is placed at the top of the opening like door and window to support the portion of the unsupported wall above it continuously throughout the length of wall. It is the most important band to stop the crack in wall.
A sill band is a horizontal member which is place at the bottom of the opening to support the load of the window frame. It is discontinued at the door opening.
A plinth band is a horizontal member which is positioned at the plinth level to tie the wall at plinth level.
The Function of RCC Bands:
- The lintel band ties all the masonry walls together and create a support for adjoining masonry walls loaded along the weak direction from walls loaded in the strong direction.
- They also reduce the unsupported height of the walls, hence improves stability of masonry walls in the weak direction.
- Lintel band also provides support to chhajja, and sill band support the load of the window frame.
- During an earthquake, bands sustain the shaking and hence minimize damage to load-bearing masonry building.
- They provide ductility and crack proof masonry building, as masonry buildings are as such brittle structure.
Horizontal RCC bands are provided in buildings of load bearing wall to improve their performance. Even if horizontal bands are provided, masonry buildings are weakened by the openings in their walls hence it is advisable to provide vertical reinforcement at side or corner of opening for better performance of the building.