Extension of Procter & Gamble Plant - Cairo, Egypt
This project relates to the extension of the P&G plant of Cairo, Egypt. The building is designed to produce industrial agglomerates. The dimensions of this structure are 36 m x 23 m and it is 3 storeys high. The main challenge of the project was the coordination of the technology and the seismic stress check according to the Eurocode adapted to the local Egyptian code. The static system of the building is formed by frames with concentric diagonal bracing in transverse and longitudinal direction. The static analysis was performed using a 3D model in Scia Engineer to optimize the weight of the load-bearing steel structure.
Building geometry and structural system
- Total steel weight: 278 tons
- Dimensions: Height: +-16 m
- Overall length: 36 m
- Overall width: 23 m
The design was based on Eurocode standards. The static system of the structure is in transverse and longitudinal direction stabilized by bracing.
The static analysis was calculated using a 3D model in Scia Engineer software with Linear, Dynamic-seismic and Steel modules.
The structural design of basements was made by a local company based on outputs of our analysis.
The wind load design was based on Uniform Building Code, vol. 2. and modified to the local Egyptian code
- Wind basic speed 145 km/h
- Wind pressure 0.996 kN/m2
The technological load was given by a mechanical part of the project. The weight of the equipment is considered in two cases: a full and an empty one. These loads were combined for adverse effects on the structure. Horizontal forces in the model represented
support reactions of piping, bucket elevators and hoists.
The seismic design was based on Eurocode EN1998
- Subsoil type - D
- Direction - Horizontal
- Coeff. accel. ag - 0.4
- ag - design acceleration - 3.92266
- q - behaviour factor - 4
- S soil factor - 1.35
The mass participated values were more than 90% so we could assume that the calculation included higher significant modes. The seismic load was input by the elastic response spectrum using 121 eigenmodes until frequency value 30 Hz.
Structural 3D modelling
The design process has been worked out in
Scia Engineer. The structure has been completely modelled with 26.606 1D beam elements in 3D. Technology, live, dead and seismic loads have been applied to the load-bearing structure.
Calculation included several steps:
- A linear calculation using a 3D frame model for the gravity loads (self weight, dead load, live load, technological load).
- A dynamic-seismic analysis using a CQC type of the evaluation with a 5% damping.
- A check of steel elements using a steel module for gravity load. The check of steel elements for seismic loads was calculated separately according to EC8.
Parameters of the structure were modified step by step according to the technological demands. The static system of the building is formed by frames with concentric diagonal bracing (dissipative zones in tension diagonals only) in transverse and longitudinal direction.
The systems of bracing were active tension diagonal bracings, in which the horizontal forces can be resisted by the tension diagonals only, neglecting the compression ones.
It was necessary to check a lot of different possibilities to find an optimised and economical solution. The project has been successfully completed and has become operational.