Metrology Tower Structural and Seismic Design
Eadon consulting, working alongside Lindhurst Engineering Ltd and Zeeko Ltd completed the detailed structural fabrication drawings for a tower which is to be manufactured in India and will be installed in a new facility in Dehradun in the northern part of the country.
In Partnership with
Lindhurst Engineering Ltd
Dehradun is located in a region of high seismic activity, this meant the 4 story structure had to be designed using a dynamic analysis to the Indian seismic and structural steel design codes. The seismic analysis implemented was a response spectrum analysis using STAAD Pro Finite Element software. The code also required the tower to be designed as a special moment frame system with pre-qualified connection designs used to satisfy joint rotation requirements.
The tower enables the stage-mounted interferometer to be operated at multiple heights above the ultra-precision polishing machine, which is housed on the ground floor. The interferometer is operationally sensitive to significant structural vibrations. Because of this an additional analysis was carried out to consider the tower response to an externally applied impulse time history loading. This was assessed against a decay criteria set by Zeeko Ltd.
Access for operation and maintenance of the stage mounted interferometer is required at each level. Each stage mount is at an enclosed floor level with safe personnel ladder access. An integral mechanical hoisting system, located on the 4th floor, allows installation of the interferometer at each operating position.