【Construction life】Safety support engineering - the relative size relationship of some horizontal support members and gantry

In the past, I thought it would be better for the manufacturer to handle the work items such as gantry and horizontal support. I didn’t know the relative relationship between them. I didn’t know the minimum net size for this project until the height of the horizontal support was too shallow.

The two projects of retaining wall and horizontal support are sometimes carried out by the same manufacturer, and sometimes divided into two, mainly depending on the form of the retaining wall, continuous wall + horizontal support, then there will be two manufacturers; Rail pile + horizontal support, it is easier to be the same manufacturer, no matter which one, it is actually a hypothetical project, which means that Taiwan often uses continuous wall as a formal basement exterior wall structure, anyway, it is made of reinforced concrete , cost considerations Ma.

gantry composition

In the case of large bases, in order to allow earthwork, steel reinforcement materials, formwork materials and other materials to be transported out of the construction area or into the construction area smoothly, a construction platform will be made in the center of the base, and the construction platform is composed of the following components: Each component has its own certain depth. Here are the examples that I have encountered as follows:

• Clapboard
• web beam
• girders
• co-structural pile

The above is the component part supporting the co-construction pile, and there are two layers of horizontally supported longitudinal beams and beams. In addition, there are fixed tripods for peripheral beams. The cross-sectional dimensions of these beams and steel beams will be based on the size of the excavation area. The difference is that the larger the excavation range, the larger the beam is theoretically needed to support.

Clapboard

The cladding board is the part where the car goes on the top layer of the gantry, with a thickness of 10 cm. It straddles the sub-beam. Usually, each piece has a hole. It has two functions. For transportation, the area is 1m*2m, 1m*3m, 1m*4m. You don’t need to worry too much about working in the construction plant. The manufacturer known as safety will calculate the quantity by itself. We calculate the money for the construction manufacturer based on the area.

↑Clad board

web beam

The horizontal beam that directly supports the clad board is a web beam, and the arrangement of the web beams will be relatively dense. If you use a 1m*2m clad board, the spacing between the web beams cannot exceed 2m, which is a common stacking of building blocks. The problem, you have to touch the edge of the ground to make it piece by piece, and the depth of the web beam is 35cm.

↑The web beam supporting the cladding board will be denser

girders

With the above logic, you can know that the frame is used to support the sub-beam, and it will not be as dense as the sub-beam. After all, the sub-beam is not as short as the cladding board. The logic of its spacing is one at the head and one at the end, and another in the middle. Don't let it sag, so a sub-beam should be supported by three beams, and the depth is also 35cm.

Auxiliary beams and main beams can actually use different sizes, which will not be particularly noted on the structural drawing, so there is no problem of construction according to the drawings, but because of the convenience of material preparation and construction, manufacturers usually use the same size, so it is not necessary on site. It's easy to make mistakes over there for a long time, because of this.

↑The size of the lower beam is the same, but it is enough to support the auxiliary beam

co-structural pile

Co-construction piles are actually intermediate piles, but they are tied to the scaffold, so they are called co-construction piles. The function of these intermediate piles is to prevent the horizontally supported steel beams from being crushed on the inner side of the retaining wall. "Qu", generally made of H-beam. Unlike the rail pile, the shape of the rail pile is really the steel bar used for the rail of the rail, and the middle pile is the H-beam used for the steel structure.

↑The head of the co-construction pile needs to be covered with a cap, otherwise the girder will not be covered

Minimum depth of horizontal support

Calculate the depth of the above components, cladding board 10cm+ sub-beam 35cm+ main beam 35cm=80cm, assuming the position of the cladding board is at GL0, then the top of the horizontal support should be at least at the position of GL-80cm, but leave 10cm of work space, so The top of the horizontal support will be at the position of the GL-90.

The horizontal support steel beam is 30cm (this will be based on the structure diagram), and the vertical and horizontal directions are 60cm, which means that the bottom of the horizontal support must be at least -150cm, and there is a tripod with a side length of 50cm. With these data, it can be calculated The excavation elevation must be at least two meters. Of course, only two meters cannot be constructed, and the construction space must be reduced by at least 50cm. In general, the calculation method of the horizontal support bottom and the first excavation elevation is as follows:

• Bottom of horizontal support: thickness of cladding plate + depth of sub-beam + depth of main beam + working space 10cm + depth of longitudinal beam + depth of cross beam
• The bottom of the first excavation: horizontal support bottom + tripod + construction space 50cm

↑The relative size of the gantry components

Epilogue

The so-called inattentive thing is not a long-term wisdom. I also know the basic size of the gantry components because I encounter the original design and I will not dig deep enough. Otherwise, I usually don't pay attention to those things at all. If you have nothing to do, chat with the manufacturer and they will teach you. many things.

The engineering-related articles I wrote are all organized in this " Engineering Series Articles ", and will continue to be updated in the future, I hope to be helpful to you.