Case History

Millennium Tower | Vienna, Austria

The Millennium Tower, at 202m, is one of the four tallest buildings in Europe. The structure is constructed on a preloaded piled raft foundation. The soil at the site was improved by vibrocompaction and the excavation was contained within a tieback diaphragm wall. 12 dewatering wells lowered the high groundwater level from the adjacent Danube river.

The ground movements due to excavation, pumping and subsequent loading by the rising building were measured by an extensometer installed close to the vertical axis of the tower. The extensometer was fitted with 5 vibrating wire displacement transducers and hydraulic bladder type borehole anchors located at different levels between depths of 26m and 60m.

A flatjack was inserted at the interface between each pile and the raft, and pre-loading was carried out using the raft and the weight of two sub-floors. The hydraulic pressure at the flatjacks was measured with vibrating wire pressure transducers.

Additionally, a central bored pile, located close to the extensometer, was instrumented with 12 vibrating wire rebar strain meters in four arrays at approximately 2m, 5m, 8m and 12m depths.

All the instruments were measured automatically during the pre-loading cycles with a Micro-10 DataLogger.

For more information, please contact Carlos Fischer: scanrock@t-online.de

Scanrock, GmbH | Schloßplatz 8 | D-29221 Celle | Germany Tel: 49-5141-28200 | Fax: 49-5141-6205

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Instrumented reinforcement cage installation.