Challenge:
A de-Ionized water storage tank together with an emergency diesel generator are to be built on a foundation next the several buildings. The tank contains 160,000 gallons of useful water plus a five-feet depth water for minimum water head. The tank and generator are to be protected from server environment including tornado. The site is on a relative soft soil profile; and soil-structure interaction effect is to be considered. A cutout of 1′ X 3.5′ in the basemat is required for the passage of piping.
Resolution:
Our engineering team designed a 3.5′ thick reinforced concrete basemat to support the water tank and use a 1′ thick wearing slab at the less weighted generator side for embedded conducts to install the utilities. The basemat is supported by 4′ and 5′ diameter reinforced concrete caissons at an average spacing of about 10′. A reinforced concrete structure with 18-in thick walls and 17-in thick composite roof decks are built around the equipment to protect them from damage by the tornado. Response spectrum analyses with varying soil properties are used to assess the soil-structure effect. The reinforcement for the caissons in the basemat are very congested which requires special arrangement to meet the construction requirements. During Installation of the caisson, some caissons have to be relocated due to clearance issue with the existing structures and due to boulder in the soil at depth. Field modifications of the reinforcement for the basemat and at top of the caissons were made to avoid congestions between the reinforcement and installation issues.
