# Practical Examples of piled raft

#### Calculation methods

In the analysis of piled raft, each pile is treated as two units - pile shaft and pile base - with a uniform settlement along the pile shaft and in the pile base. This assumption allows modeling of non-linear behavior based on the empirical relationship of the load-settlement line according to DIN 4014 or EA-Piles.

As a combination of empirical and theoretical approaches, a new method has been developed for the nonlinear computation of piled rafts. It meets the requirements of the KPP Directive.

#### Multiple models for analyzing piled raft foundations

The behavior of the pile-soil system can be examined by considering linearly or nonlinearly analysis.
One distinguishes between the following nonlinear analyses of piled raft foundations by:
1- A hyperbolic function for the load-settlement curve of the pile
2- Using German Standard "DIN 4014" for the load-settlement curve of the pile
3- Using German recommendations "EA-Piles" for the load-settlement curve of the pile
4- A given load-settlement curve of the pile

Analysis of Piled raft of Skyper in Frankfurt by ELPLA

Skyper is 154 [m] high-rise building supported on a piled raft foundation. The tower was one of the tallest three skyscrapers in Frankfurt, Germany when it was completed in 2004. Using the available data and results of the Skyper piled raft,  the nonlinear analyses of piled raft in ELPLA are evaluated and verified using the following load-settlement relations of piles, El Gendy et al. (2006) and El Gendy (2007):

1- Hyperbolic function.
2- German standard DIN 4014.
3- German recommendations EA-Piles (lower values).
4- German recommendations EA-Piles (upper values).

The foundation system is analyzed as rigid or elastic piled rafts. In which, the raft is considered as either rigid or elastic plate supported on rigid piles. A series of comparisons are carried out to evaluate the nonlinear analyses of piled raft for load-settlement relations of piles. In which, results of other analytical solutions and measurements are compared with those obtained by ELPLA.

Analysis of Piled raft of Burj Khalifa in Dubai by ELPLA

Using the available data and results of the Burj Khalifa piled raft, which have been discussed in detail in the previous references, the nonlinear analyses of piled raft in ELPLA are evaluated and verified using the following load-settlement relations of piles, El Gendy et al. (2006) and El Gendy (2007):

1- Hyperbolic Function for Load-Settlement Curve.
2- Given Load-Settlement Curve.

The foundation system is analyzed as an elastic piled raft in which the raft is considered as an elastic plate supported on equal rigid piles.

A series of comparisons are carried out to evaluate the nonlinear analyses of piled raft for load-settlement relations of piles. In which, results of other analytical solutions and measurements are compared with those obtained by ELPLA.

Analysis of Piled raft of Shanghai Tower by ELPLA

The Shanghai Tower is a mega tall skyscraper in Lujiazui, Pudong, Shanghai, ‎Figure 8-1. It is considered the second-tallest building in the world after Burj Khalifa. The height of the tower is 632 meters. It consists of a 124-storey tower, a 7-storey podium and a 5-storey basement.

Using the available data and results of the Shanghai piled raft, which have been discussed in detail in the references, the nonlinear analysis of piled raft in ELPLA according to El Gendy et al. (2006) and El Gendy (2007) is evaluated and verified using the load-settlement relation of piles from the pile load test given by Xiao etc. Al. (2011).

For simplicity, the piled raft is considered double symmetric and only a quarter of the foundation system is analyzed. The foundation system is analyzed as an elastic raft supported on unequal rigid piles.

Analysis Piled raft of Messeturm in Frankfurt by ELPLA

Messeturm was the tallest high-rise building in Europe until 1997. ‎The building lies in Frankfurt city in Germany. It is 256 [m] high and standing on a piled raft foundation.

Using instruments installed inside this foundation, an extensive measuring program was established to monitor the behavior of the building. Because these instruments record raft settlements, raft contact pressures and loads on pile heads and along pile shafts, the building was a good chance for many authors to verify their analysis methods for piled raft.

A series of comparisons are carried out to evaluate the nonlinear analysis of piled raft using DIN 4014 [5] for load‑settlement relation. In which, results of other analytical solutions and measurements are compared with those obtained by the present analysis. In the comparisons the present analysis is termed NPRD.

Analysis of Piled raft of Torhaus in Frankfurt by ELPLA

Torhaus is the first building in Germany with a foundation designed as a piled raft. The building lies in Frankfurt city in Germany. It is 130 [m] high and rests on two separate piled rafts, where a street passes under the building. Measured instruments were installed inside the foundation to record piled raft settlement and stress. Many authors studied the foundation of the Torhaus and applied their analysis methods on piled raft. Some of them are Sommer et al. (1985), Sommer (1989) and Reul/ Randolph (2003).

Comparisons are carried out to evaluate the nonlinear analysis of piled elastic raft using composed coefficient technique. Here results of three-dimensional finite element analysis and field measurements are compared with those obtained by the present analysis. In the comparisons the present analysis is termed NPRH.

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29 August 2021
14 February 2021