Rapport - It.civil.aau.dk - Aalborg Universitet

64 KAPITEL 9. SUMMARY
Prestressed slabs from Spaencom are used as floors. The initial cable tension
was set to satisfy requirements to the stresses in the top and bottom at
the time of prestressing and with working load. Secondly the effective cable
tension was computed with consideration of initial strain, creep, shrinkage
and relaxation. The deflection was calculated in both short and long term.
At the ultimate limit state the resistance of the slabs against bending moment
and shear force was examined with the strain from the prestress taken
into account. Additionally it was verified, that the wall had sufficient bearing
capacity through 120 minutes of fire.
Finally, a joint between a slap and two panels was designed to resist the loads
at the ultimate limit state, and also to satisfy the robustness requirements
of DS 411.
9.2 Foundation
It is estimated that the best solution is to found the southern part of the
building on piles, because the layers capable of bearing are low down. In the
northern half it is estimated that the most economic solution, is to found
directly on a sand pile filling. The foundations are located under the bearing
walls, but are not designed in this project.
To pour the basement it is necessary to establish a building pit. To avoid
elevation of the ground the groundwater level needs to be lowered. Because of
the depth of the sandlayer, where the groundwater level needs to be lowered,
a wellpoint system can not be used. Instead a system consisting of three
pump wells is designed. It is verified that the pressure level is within the
assumption of an artesian stream and on the same time without risk of
elevation. In addition, pumps are used to remove surface water.
Moreover the pit enclosure is designed. Specifically sheet piling is used, which
is designed as both cantilever and anchored. In addition, it is designed both
with and without differential water pressure, due to the existence of intermediate
sand layers, where connectedness to the inlet can not be determined.
When designing the cantilever sheet piling the required penetration depth
is high, thus it is judged to be uneconomic. The anchored wall is designed
with one pin joint. Moreover the anchor is designed, and it is verified that
the total stability of wall and anchor are sufficient.