Structural Engineer Richard has been talking to us about the technical engineering elements that go into an existing building and how we can make structural changes for our designs.
The structure must not collapse
The structure must be serviceable
The structure must be buildable
- build ability
Must contain at least on viable load path for transferring each load applied to the structure.
- loads/actions act externally to a structure
- forces act within
Tension – causing an element to extend
Compression- causes element to shorten
Shear- causes shear deformation
Bending moment- causes an element to bend
What are potential loads/actions acting on a structure?
- Gravity (vertical load)
- Earth pressures
- Water pressures
- Wind load
- Seismic load
- Blast loading
- Thermal expansion/shrinkage
- Differential settlement
Establishing load paths for new buildings is fairly easy, however existing buildings can be much more difficult. You have to think what are the existing load paths and how to get them to the ground.
‘A structure will not collapse until it has exhausted the load path and can no longer stand up.’
How will the load paths be affected by construction works?
- Temporary support
- Consider all stages of construction
- Don’t forget about the foundations
- Reversibility and readability
- Stiffness is often critical – proportional to depth squared
Façade retention – keep part of the external wall and build your own structure over it.
- examples shown in Fargate, Sheffield
New or enlarged basements beneath existing buildings
- Under pin the foundations
Bungalows and Bears- Old Fire Station, Sheffield
The original building was designed in 1930’s and designed for fire trucks bays so they had to be long spanned.
What building/site constraints might affect your proposals?
- A lot of columns
- Division street is popular and busy
- Couldn’t close the path for construction- work from the back of the site