THERMAL EFFECTS OF UNDERGROUND CARPARK STRUCTURE A COMPARATIVE STUDY OF UNDERGROUND CAR PARK CONCRETE BUILDINGS IN DUBAI - UNITED ARAB EMIRATES
The British University in Dubai (BUiD)
The underground car park buildings considered as an ideal solution for the parking spaces in urban area, and it is more commonly used when the land values are high. So, the main intention to have a durable and economical building along it service life. Particularly these types of buildings are vulnerable to the structural distress related to the restrained volumetric change due to the shrinkage and thermal change during the parking operation, many of the designers and owners avert to have a separation in the underground structure, especially when the water table is very high. But Ignoring the thermal effects with the structure stiffness characteristic can lead to premature deterioration and cracking because of the generated forces. This study intent to show the importance of thermal analysis of underground car park concrete building, by conduct a comparative study between three models of three floors underground car park building, with length around 147 m and width around 38 m. The first model analyzed the building for the gravity load only, and the second model analyzed the building for gravity load and thermal change in absence of expansion joints, while the third model analyzed for the gravity load and thermal change in present of expansion joints. The analysis of the three models shows how the thermal change of underground parking structure affect members internal forces with unexpected amount, which at some extend are not considered in the design by most of the designers. The forces produced from the strain forces (thermal changes) must be well studied as it is different than the forces produced from the gravity loads, generally these forces affect the connection design, specially between the walls and slabs or columns and slabs, and how this effect is reduced by the presence of expansion joints. The comparisons between the three models covered the comparisons of structural elements forces (columns, Slabs and the walls), in addition to the comparison of the whole building maximum drifts and maximum displacements, and the columns shear forces which produced specially on the columns in both directions due to the horizontal movements of the slabs due to the thermal changes. These forces and results record in a manifest the maximum in the model analyzed for thermal stresses with full building length (without expansion joints), while the presence of the expansion joint results in structure with less slab stresses, wall stresses, building drift and displacement, member forces which in-turn lesser section properties and reinforcement hence leading to economical design of the structure.
parking spaces, economical building, thermal change