UK Rigging – Spider lift at the Leeds Grand Theatre

TSG were contacted by UK Rigging to create a solution for the inspection of a plasterwork ceiling at the Leeds Grande Theatre. They wanted to drive a spider lift into the centre of the auditorium to be able to fully inspect all areas of the ceiling from a single position. This would entail the construction of a platform that that could support the spider along with suitable access.

Design challenges

There were a number of obstacles to overcome.

• The position that the spider lift had to get to was across the theatre seating.
• The centre position could only be accessed from the Stage
• The legs of any platform had to sit in specific locations due to the positions of the floor steel work
• The imposed loads of the spider in travel and deployed modes.
• It only needed to be used once a year

Design Solution

Between ourselves and the client we elected to use a standard truss product that would supplement their inventory as the basis of the platform and bridge access. This product was identified as Slick GS Truss. This provided a maximum strength for a relatively small truss and would add to the clients existing inventory.

This truss structure would then have a series of spanning decks both on the main platform and the ramp to allow the Spider lift to travel to its finished position to allow for the inspection.

Calcs

With the spider lift having a self-weight of 3,040kgs attention had to be taken payed to the imposed loads for the operation of the equipment. The spider lift would induce a point load of 2800kgs with the outrigger when in the deployed position and have a traffic live load of 700kgs/m2 when travelling. These were all extremely high loads to be analysed that would have an effect on the design of the structure in different places and at different points in time.

The Result.

The resulting scheme was an easily deployable truss structure and had 90% standard components with easy fix plywood clad decks allowing for smooth travel of the spider.