Common, inevitable building movements and deformations include: differential column shortening, lateral story drift, building racking, slab and beam deflection, thermal deformation and building dynamic vibration, etc.
When subjected to gravity loads, vertical reinforced concrete structural members, such as columns and shear walls, experience short-term and long-term shortening that is zero at the base and accumulates to be the maximum at the roof level.
For interior partitions, allowance is needed for differential deflection between two adjacent floors after the installation of interior partitions.
There have been numerous examples where these joints have not been appropriately installed, particularly on tall slender buildings, which results in “creaking” complained by tenants because of rubbing joints as the buildings move under wind loading.
The selection of a specific methodology will depend on the project parameters as well as the designer's preference.
Method 1: Free-floating The first method for accommodating thermal expansion or contraction in a riser with grooved couplings is to build a free-floating system in which the movement is directed to the top of the riser with a base anchor and guides.
The long-term deflections of girders, which pick up floors above, are particularly important and the deflection acceptance criteria should be more stringent than code-allowed values.
Absolute long-term deflection limit values for the girders are recommended to control associated deflection of floors above, instead of satisfying the code-allowable deflection-over-span ratio alone.
Additionally, the width of the flexible pipe-coupling housing allows for pipe-end separation, leaving room for controlled linear and angular movement.
When subjected to variations in temperature, piping will experience linear expansion or contraction.
The key to effectively accommodating this thermal movement in a building's riser piping is to allow the predictable, controlled movement of the piping.
Grooved for riser piping When installed with design considerations in mind, grooved mechanical couplings are capable of accommodating piping thermal movement.
This means that to achieve this added benefit, system designers must recognize this critical characteristic when specifying grooved pipe-joining systems.