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willio
willio • Sep 10, 2017

Structural engineers: can I humbly ask some advice so I don't screw this one up?

Hi, this is my first post.

I recently took over a project where I get to convert an old factory (basic steel frame) into a modern warehouse building, while expanding the area into a bigger logistic center. After being involved with experienced welders, one got the itch to actually design something that does not look boring. A few hours in SketchUp, I came up with a gate structure with two wings as its cantilevered canopy, stacked in the middle is security room/checkpoint booth. (see attached.)
  • The wing canopy will use 5x5cm galvanized stall as cremona frame. The backbone (0.2x0.2x12 metre) will be supporting the water gutter, and the roof sub-structure (single stall in the photo, it'll be cremona too)
  • Wing span is 12 metres long each side, 4.5 metres width. (108 sqm)
  • Estimated external load based on rainfall data is about 3.5 cubic metre (2160kg).
  • Main beam (reinforced concrete) are 4 metres, with 6 metres steel bearing beam.
  • Center tower is 3 by 6 metres, will support a poured-concrete roof that will house two rainwater collection tank (2 cubic metre), filtration system, and clean water tank. (1-2 cubic metre.)
I'd like to stay as close as possible to the rendering of the design. This is not a public place, but a commercial one, so I try to keep the budget low by using common materials (rebar, concrete, galvanized stalls, roof, tube pipes, nothing fancy/custom) built using common tools. My questions:
  1. What's your immediate thoughts? Is this is a sound structure? What's missing? Can I loose something without loosing structural integrity?
  2. What would be the minimum tube pipe size/thickness to be used as the extension beam (above the reinforced concrete beams)?
  3. Any software/tool that can help simulate load and study this further?
I'm really new to civil engineering, I'd appreciate your kind feedback. Thank you.
This is way out of my area. Still I feel that the 108 sq.m. wings may pose wind force problems. They look like aircraft wings and may see large lift forces even in moderate winds. Behavour in gusts can be worse. I am sure that these were taken into account.
willio
willio • Sep 11, 2017
A.V.Ramani
This is way out of my area. Still I feel that the 108 sq.m. wings may pose wind force problems. They look like aircraft wings and may see large lift forces even in moderate winds. Behavour in gusts can be worse. I am sure that these were taken into account.
Hi AV, thanks for your comments.

Wind factor is one of my main concern. Weight is considerably well distributed, and the symmetrical structure allows the entire wing span to actually sit balanced on the water tank in the middle of the concrete. So the key will be the joints of the pipe on the upper and lower side of the wings. Any input on what type of brackets/joints to connect the pipes and the frame?
I am sure that the Civil experts here can give you better advice.
Indonesia is prone to seismic disturbances and seasonal typhoons. I see tie rods both above and below the canopy. Could you add two more pairs linking the far end of the backbone to the concrete tower? This will not materially affect the nice airy design. It might prevent a bending wind force at the present support point at the center of both the backbone beams.
Standard supports should work. These have to be sized to handle the maximum expected typhoon winds. Maybe existing archival typhoon data can be used for calculations.
I must reiterate that this is not my area of work. I am talking more as a layman.

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