The roof space frame of the main workshop of coal preparation plant is a bidirectional orthogonal diagonal quad-pyramid structure, 56m long, 35m wide and 3m high. The lower chord mesh is 3.5m and the upper chord mesh is 2.745m. The space frame adopts welding ball node, the ball and the rod are Q235 steel, the rod and the ball are connected by cutting butt welding.
The space frame is simply supported on the reinforced concrete frame beam with elevation 34.780m. The bearing form is single-sided arc pressure bearing. The design requirements of the grid arch, arch height 140mm. Net frame weight 78t, steel capacity of about 40kg/m2. Two 5T electric single-beam cranes are suspended at the lower chord nodes of the grid, with a span of 14m.
The construction sequence of the space frame is as follows: bar cutting → plane monolithic truss making → total assembling → welding, painting → hoisting → aerial assembling → emplacement fixing.
On the floor of 20.700m, it is put together as a whole and hoisted with 4 raking rods.
Because the space frame size of the surrounding support girder is only 34.620m×55.620m, and the size of the space frame’s skin is 35.360m×56.360m, the whole assembly can not be completed at one time. Half of the space frame on both sides need to be assembled after lifting over the height of the support. At this time, the size of the space frame skin is 33.610m x 54.610m. Although the scheme needs to increase hoisting equipment, the overhead splicing workload is reduced, and the assembly quality is easier to guarantee than the former. The overall assembly starts from the middle, first with the lower chord, then with the belly and the upper knuckle, and finally with the upper chord. As the length of the rod is greater than the net distance between the two balls, it is necessary to use a sledgehammer to gently knock the rod into the two balls when assembling, or use an inverted chain to pull the ball apart and squeeze the rod. After the rod and the ball are consistent and fixed by spot welding, they will be assembled on both sides in turn until the end.