Original title: Harm of opening on beam and correct method of opening Source: Huajian Environmental Design Institute, Refrigeration Encyclopedia Mechanical and electrical network, civil bar If there is infringement, please contact to delete. Because it can save the clear height space, the opening on the beam is a problem we often encounter in the mechanical and electrical design and daily decoration. Therefore, as mechanical and electrical professionals, we should also understand some basic knowledge of the structure. The following article can take you to understand the basic knowledge of opening holes on beams. 01 Basic structure of beam As far as the houses we live in are concerned, most of them are frame structures, mainly composed of beams, columns and slabs. Beam: generally reinforced concrete beam (hereinafter referred to as beam), and the most important structural function of the beam is embodied in the steel bar. Reinforcement: The beam contains three main reinforcements with different functions, namely longitudinal reinforcement, stirrup and waist reinforcement. The diameter of longitudinal reinforcement is 14-22 mm,bra measuring tape, the diameter of stirrup is 6-12 mm, and the diameter of waist reinforcement is 10-12 mm. Expand the full text 02 Harm of opening on random beam "The design of architectural decoration and fitment engineering must ensure the structural safety and main use functions of the building.". When the main body and load-bearing structure are changed or the load is increased, the original structural design unit or the design unit with corresponding qualifications must check the relevant original data and verify and confirm the safety of the existing building structure. Article 3.1.5 of Code for Acceptance of Construction Quality of Building Decoration (GB50210-2001) In the absence of the feasibility report issued by the original structural design unit, the construction unit and the owner of the house shall bear the relevant legal responsibilities if the original structural load-bearing beam is opened and penetrated without authorization. In general, there are two ways to go to the top of water and electricity during decoration construction: 1. Conduit around beam 2. Opening on beam When drilling holes on the beam,retractable tape measure sewing, the main steel bars should not be hit to ensure the stability of the beam structure. However, in many cases, there are violent holes in the construction and installation of air conditioners. Let's take a look at a group of pictures. Hole diameter is too large (beam is broken) One porous (the beam has been abandoned): One beam is porous (the beam is cracked): The hole is at the lower opening of the beam (the reinforcement at the lower opening of the beam has been broken): When the reinforced concrete beam is subjected to bending, it is subjected to local compression and local tension. The concrete bears the pressure and the steel bar bears the tension. The two cooperate with each other and are indispensable. If the longitudinal reinforcement of the main beam is broken in the process of installation and construction, the tension of the beam will be borne entirely by concrete, and the seismic performance will be greatly reduced. The risk of breakage of reinforcement, especially longitudinal reinforcement, is related to the floor height. If the low-rise house breaks the longitudinal reinforcement of the main beam, the seismic capacity of the whole building will be much worse. In addition, bespoken tape measure ,garment measuring tape, we need to know the importance of reinforcement, that is, longitudinal reinforcement > stirrup > waist reinforcement. As shown in the figure above, the red area is a very important stress area for longitudinal reinforcement, which must not be broken! 03 Hole diameter and position of opening on beam Air conditioning copper pipes are generally laid close to the beam and wall, and the drilling position is generally in the beam root area (near the support), so special attention should be paid to the detection of stirrups in the drilling process. Generally speaking, the aperture of frame beam is recommended to be less than 100mm, and the aperture of secondary beam is recommended to be less than 200mm. The position of air conditioning opening can be divided into "upper, middle and lower". Everyone agrees that the lower part of the air conditioning opening beam can not be hit. There are also some sayings that "the opening should be hit in the middle as far as possible, and the main steel bar will not be hit.". So is that really the case? In fact, whether you can play in the middle depends on whether you have a waist tendon. When the beam thickness exceeds 450mm, the waist reinforcement will be set, but the beam thickness is not the actual beam thickness we see. Since the real thickness of the beam can not be measured, how can we judge whether there is a waist tendon inside the beam? The key is whether the thickness of the floor has certain specifications. According to the national building structure regulations, the thickness of the floor is 100-120mm. Taking a beam thickness of 450 mm as an example, the thickness of the visible part ranges from 330 to 350 mm. Then, the actual measured thickness of the beam can be 350 mm as the standard to judge whether there is a waist reinforcement inside the beam. That is to say, if the measured beam thickness is more than 350mm, there is a waist reinforcement inside the beam, otherwise there is no waist reinforcement. Let's take a look at a few photo captions. ① The measured "beam thickness" is less than 35 cm (without lumbar tendon) For this kind of beam, we only need to avoid the lower row of longitudinal reinforcement (main reinforcement) when drilling. Generally, it is recommended to drill more than 8cm away from the lower part of the beam, as shown in the following figure: ② The measured "beam thickness" is more than 35 cm (with lumbar tendon) In this case, we can choose the middle area of the waist tendon and the upper and lower rows of longitudinal tendons to punch, but it is difficult to determine the specific location of the waist tendon in the actual punching, so it is difficult to determine the punching location. In this case, the upper position can be drilled close to the floor slab; the lower position can be drilled close to the lower edge of the beam at a distance of 8 cm. If drilling at the lower position, there is a risk of breaking the longitudinal reinforcement (main reinforcement), while drilling at the upper position only has the risk of breaking the waist reinforcement, so we suggest that drilling at the upper position should be considered as far as possible. 04 Reserved opening It is the best choice to reserve the opening on the beam in the design stage. With the technical support provided by the structural colleagues,keychain tape measure, it will certainly not go wrong. What should we do to destroy the main load-bearing structure in order to take the equipment pipeline? See how Daxing Airport is solved? The beam is cut out The rebar is broken In Daxing Airport, open beams are made in one direction. At Daxing Airport, the armpit beam is added in the other direction Return to Sohu to see more Responsible Editor:. tape-measure.com