Project Overview
Purpose, client requirements, and key challenges.
The client wanted a 3-tonne crane installed in the plant workshop to move equipment and goods around. Their goal was to maximize the space and give as much lift-height and travel as possible. After a site survey I came up with the following specification:
-
WLL: 3 tonne
-
Max H.O.L: 3.6 metre
-
Span: 3.5 metre
-
Long Travel: 9.5 metre
The picture below shows the space before we installed the crane. The most challenging requirement was that I could only place supports next to the 4 existing roof support columns. This meant that there would be a significant cantilever on both ends of the gantry.
Design and Engineering
Concept development, calculations, materials, and compliance with standards.
I sized the main structural elements of the crane using a combination of Finite Element Analysis (FEA) and hand calculations in accordance with BS EN 1993-6. With bridge cranes, the governing constraint is typically the allowable deflection of the runway beam. The FEA plots below show the predicted deflection of the gantry under the rated load. This deflection was confirmed by the load test that was carried out after installation.
Materials of Construction:
· BS EN 10025-2 S355JR (1.0145) Universal Beam
· BS EN 10025-2 S355JR (1.0145) Universal Column
· BS EN 10219-1 S355 J2H (1.0576) Square Hollow Section
Standards:
· BS EN 1993-6:2007 – Eurocode 3. Design of steel structures – Crane supporting structures
· BS EN 15011:2020 – Cranes. Bridge and gantry cranes
Manufacture and Assembly
Fabrication methods, quality control, and assembly process.
Fabrication was carried out in our workshop by coded welders. The design of the gantry required that they runway beams be supplied in one 9.5 metre piece each, which meant that moving them around the shop required the overhead cranes and special consideration.
All finished parts were measured against the fabrication drawings to ensure accuracy. The finished parts were sent for powder coating to provide better durability over paining for the life of the crane.
Assembly was carried out primarily on-site by our site services team.
Testing and Implementation
Installation was carried out by 2 site engineers over 10 days on-site. The bridge was assembled in our workshop and then transported to site to be lifted into place.
Load testing was carried out by lifting 3.75 tonnes (125% of the capacity) to confirm that the load limiter in the hoist was working properly. Following that, the load was reduced to 3 tonne and the crane was run through a full travel to each end of the span. At the end of the cantilever with the hoist at the far end of the bridge beam, the deflection was measured at 3mm.
Outcomes and Lessons Learned
The project was completed on schedule, with the install taking place in November 2024; the crane has been in service for 1 year with no issue. At the time of install I spoke with the site contact, and he was pleased with how smoothly the installation had gone. He made a point of mentioning that he prefers using us for site services because our site engineers are good to work with and carry out their work professionally.
