Composite member is composed of precast concrete member and post cast concrete, which is formed in two stages as a whole stressed structural member; composite floor is the most commonly used fabricated horizontal member in prefabricated building
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The precast layer of the composite slab can be used as the permanent formwork of the upper cast-in-place composite layer, and the horizontal equipment pipeline can also be laid in the cast-in-place layer
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The mechanical and electrical systems of equipment in different functional buildings are very different, so the openings and pre burying in the precast slabs of composite slabs are also different
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Whether it is the open installation or the concealed laying of the pipeline, it will be more or less reserved and embedded on the laminated plate
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The accuracy of the detailed design of the reserved and embedded on the laminated plate will have a direct impact on the processing and production of the prefabricated components and the construction and installation in the construction stage
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The commonly used composite plate is truss reinforced concrete composite plate (60mm thick floor)
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The special structure of truss reinforcement will also have a great impact on the reserved opening and wire box embedding
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Combined with the practice of composite floor design and installation engineering of prefabricated building, this paper mainly analyzes the common problems of composite floor design and later construction, and puts forward the optimization measures of modifying the construction drawing design and professional cooperation in the detailed design stage, so as to improve the efficiency and quality of the detailed design of prefabricated building components, and reduce the cost of prefabricated components The adverse effects of processing production and component assembly construction
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Background: laminated floor is a relatively simple component in the construction and implementation of prefabricated buildings
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However, in the actual engineering practice, due to the lack of professional cooperation in the construction drawing stage and the lack of detailed design, the reservation and embedment on the laminated floor is missing or inaccurate, which causes problems in the component processing and construction installation More rework, which greatly affects the construction period and causes greater economic losses
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Combined with specific projects, the following lists the common problems of reservation and embedment on the composite slab: 1) the design height of truss reinforcement is wrong, and the concealed laying pipe on the composite cast-in-place layer can not pass through the truss reinforcement, resulting in the on-site construction to remove the groove on the precast slab or increase the support, and cancel the upper chord of local truss reinforcement; 2) there are many and concentrated local pipelines on the composite cast-in-place layer, and the centralized and large diameter pipes can not pass through Through the truss reinforcement, the truss reinforcement and precast slab in the local part of the pipeline are cut off in the field construction; 3) the embedded part of the mechanical and electrical box is missing, and when there are many mechanical and electrical systems or there are special needs, the small system points are often missed in the deepening design, resulting in the installation of the wire box in the field construction; 4) the distance between the embedded part of the mechanical and electrical box and the design point is large, which causes the decoration and installation points to meet the design requirements The position deviation is too large, resulting in re opening and installation of wire box in site construction; 5) the influence of truss reinforcement is not considered in the embedded and incoming direction of electromechanical wire box, the embedded position of wire box is close to truss reinforcement, and the incoming direction collides with truss reinforcement, resulting in re opening and no lock nut in the wire box after adjusting the incoming direction on site; 6) the embedded position of electromechanical wire box is close to the edge of precast slab, so it is easy to lift and transport In the process of transmission, the damaged wire box needs to be removed and re installed on site; 7) the reserved hole for the downward vertical threading pipe of the electromechanical equipment is missing, which causes the drilling of the composite precast slab; 8) the vertical threading pipe of the fire and water supply and drainage floor slab, and the reserved hole for the composite precast slab is missing, which causes the cutting of the composite precast slab and re opening; 9) the fire and water supply and drainage building The position and size of the reserved opening of the composite precast slab are wrong, which causes the upper and lower risers of the floor can not be connected and installed, and the site construction needs to cut and enlarge the hole of the composite precast slab; 10) the embedded casing on the composite precast slab is damaged in the process of hoisting and transportation, and the casing reserved higher than the surface of the precast slab is easy to be damaged, which causes the site construction to remove the damaged casing New installation; problems are no longer described in detail, the above errors of reservation and embedment will cause the construction site to reprocess and correct the laminated precast slab, poor site accuracy and rough post-treatment will continue to cause a series of quality problems, such as slotting behind the wire box and poor molding quality due to the loose interface after installation
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Many common problems are caused by a variety of reasons, but it can also be seen that the splitting and deepening design of laminated plate are throughout the integrated design and the whole project construction
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Therefore, it is necessary to sort out and unify the assembly content design professional cooperation and deepening design financing process of construction drawing design
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Common types of mechanical and electrical reservation and embedment of composite floor slab in view of the various detailed design problems mentioned above, it is necessary to classify and summarize the common types of mechanical and electrical reservation and embedment on the precast slab of composite floor slab, so as to facilitate the confirmation of mechanical and electrical reservation and embedment at the initial stage of detailed design and avoid missing items, and also need the deepening design personnel of structure specialty to fully understand these systems
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1) Composite floor electrical reservation and embedment (1) lighting system: the lighting system line pipe is concealed, the light box is placed at the bottom of the board, and the lighting system light box is a common reserved and embedded component in residential and commercial buildings
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For the residential projects with hardcover demand, the embedded light box must be reserved accurately at the lighting point without ceiling plate bottom, and the junction box without ceiling light in the hardcover room needs to be reserved more accurately in the laminated plate area
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(2) Fire protection system: the embedded junction box should be reserved at the bottom of the laminated precast slab when the pipeline of the fire protection system is concealed
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The embedded junction box of the fire protection system usually includes: emergency lighting, evacuation indication lighting, smoke detector in the automatic fire alarm system, fire emergency broadcast, etc
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(3) Strong current system: the control switch of the strong current system is set on the wall, and the wire pipe usually needs to reserve a circular wire hole in the area of the laminated plate
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When the pipe is laid in the cast-in-place layer of the laminated plate and needs to go down in the partition wall, it needs to reserve a circular wire hole in the laminated precast plate
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(4) Other special requirements: in hardcover residential projects, there are often special requirements for reservation and embedment, such as the junction box at the bottom of the board for security infrared radiation device, and the junction box at the bottom of the board for electric curtain junction box
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2) Reserved openings for composite floor (1) flue and air shaft openings: generally, there will be structural beams around the flue and air shaft of the floor, but the smaller flue and air shaft will directly set rectangular openings on the floor
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If the opening is at the edge of the composite floor, the truss reinforcement of the composite floor cannot be connected, resulting in poor overall stiffness of the installation direction of the composite floor
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Therefore, in the construction drawing design stage and assembly split scheme, it is necessary to avoid large reserved holes on the board
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(2) Bridge opening: the concentrated vertical bridge is often set near the wall, which is often the edge and corner of the floor
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The composite floor is set at the concentrated position where the bridge passes through the floor, and the concentrated bridge at the edge of the composite plate passes through the reserved opening
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(3) Other special requirements: the location of the construction setting out hole is generally determined before the construction, which often leads to a large number of modifications in the detailed design of the laminated plate, so it is necessary to determine the location of the setting out hole with the construction unit in the early stage of the deepening
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The cantilever frame around the construction will often set U-shaped fixed reinforcement in the indoor floor
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If the position of U-shaped reinforcement is not fixed, it will often fall in the area of the composite plate
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The 70 thick cast-in-place layer can not meet the anchoring demand, and it will also cause the back opening of the composite plate
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According to the current application situation of prefabricated building, if we improve the standardization degree of components and reduce the errors of reservation and embedding, combined with the design idea of prefabricated building, we should also put the professional cooperation in front of the reservation and embedding on the laminated slab, that is, in the construction drawing design stage, the assembly splitting scheme and the electromechanical construction drawing design should consider the overlapping design In order to avoid the adverse effect of the composite slab, the reservation and embedment on the composite slab should be reduced as far as possible
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At present, most of the projects are in-depth design of components after the completion of construction drawing design, which is missing for the optimization and adjustment of electromechanical system and the avoidance of reservation and embedment.
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