Featured Project – Old Grange Police Station
Location: Shirvan Road, Tobago
Contractor: NH International Caribbean Limited
This project, which was managed by UDECOTT, was originally designed as a structural steel framed building with a regular grid. To generate the required savings on this project for the client, we proposed a value engineering option that essentially used the interior and exterior walls as load bearing reinforced concrete walls. The original architecture had a lot of walls within the building as part of the typical design for police stations or secure facilities. These walls not only partitioned general office spaces, but prison cells blocks, interrogation rooms and ID parade areas to name a few. By using the walls to resist gravity and dynamic loads we were able to remove almost all of the beams and columns in the building. The beams and columns that had to remain were only the ones in areas where there were no walls and a lot of open space.
The decision to go with load bearing walls meant that the structure would be classified as irregular as the wall layout had no symmetrical arrangement whatsoever and furthermore, the layout of the walls at ground floor level did not match the layout at first floor level within the 2-storey building. This resulted in two issues, (i) how would the foundation work and (ii) how do we analyze the structure. The foundation was a simple solution – a raft foundation would be done to avoid having to construct a haphazard strip footing foundation that would no doubt have been an issue with this building. The analysis of the structure called for an assessment to determine if there are horizontal and/or vertical irregularities present in the building. After the assessment it was found that the equivalent static method was still applicable for structural analysis. The quantity of walls present in the building also permitted the thickness to be reduced to 100mm and still satisfy ACI Code stipulations.