Recommended unit: Shandong wansida Technology Co., Ltd Technical content: steel pipe truss prestressed concrete composite slab (pk3 composite slab for short) refers to the composite slab formed by pre tensioned prestressed concrete precast base slab with “grouted steel pipe truss” as stiffener, which is assembled on site, then reinforced on the precast base slab and poured with concrete on site.

At the same time, by adjusting the truss height, density, diameter and wall thickness of steel pipe, pk3 plate can also realize “moderate stiffness, no support and less support, wide application range and flexible selection”.

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In the construction stage, the technology realizes “no formwork, no support or less support”, which significantly improves the quality, improves the efficiency and reduces the cost of measures.

The “new assembled integral pretensioned prestressed floor system” composed of pk3 laminated plate technology and pkl laminated beam technology is a cost-effective horizontal structure technology system in the field of precast buildings.

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1 structural diagram of pk3 plate Fig.

2 sectional view of steel pipe truss the tensile material “high strength prestressed reinforcement” with the highest cost performance is used in the lower tensile area of pk3 plate, the mechanism “triangular space truss” with the highest force transfer efficiency is used in the middle, and the compressive material “grouting steel pipe” with the highest cost performance is used in the upper compression area, so as to achieve perfect stress performance.

The concrete strength grade of the laminated layer shall not be lower than C30.

The key technical indexes of steel tube truss prestressed concrete composite slab technology are as follows: 1 The material of prestressed concrete composite slab of steel tube truss should be high-strength prestressed steel wire and appropriate high-strength concrete.

For the two-way composite floor bearing uniform load, the internal force calculation under the limit state of normal use should choose a practical method, or can be calculated according to the orthotropic plate.

The concrete strength grade of prestressed concrete precast base plate of steel pipe truss shall not be lower than C40.

The slab bottom reinforcement perpendicular to the prestressed reinforcement direction in the laminated layer shall be placed close to the upper surface of the precast bottom plate; When the two-way slab is designed, the area of stressed reinforcement shall be determined according to the calculation; When designed as one-way slab, distributed reinforcement shall be configured.

The whole process of mechanical automation and mold free amortization realize the “common line production” of a variety of products, improve efficiency and reduce labor.

Coil Insert

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The thickness of post cast concrete composite layer of prestressed concrete composite slab of steel tube truss shall not be less than 75mm, and shall not be less than 60mm and 1.5 times the thickness of bottom plate.

▲ click on the above card to pay attention to the source: ASC construction industry modernization, the construction industry modernization development committee of China Architectural Society, for the new technical achievements submitted by enterprises, after consulting experts, launched 21 advanced, mature and applicable new technologies, edited and formed the compilation of “advanced, mature and applicable new technologies” of precast buildings (the first batch), which can be used for reference, promotion and application by member units and enterprises in the industry.

Technical indicators the safety and quality of steel tube truss prestressed concrete composite slab technology shall meet the current national standards general code for concrete structures gb55008, code for design of concrete structures GB50010, technical specification for precast concrete structures jgj1, technical standard for precast concrete buildings GB / t51231 Code for acceptance of construction quality of concrete structures (GB50204), technical specification for prestressed concrete composite slab of steel tube truss (T / cecs722), steel wire for prestressed concrete (GB / t5223), design standard for steel structures (GB50017), technical specification for concrete structures with welded steel mesh (jgj114), prestressed concrete steel tube truss composite slab (atlas No.

In the production stage, the technology fully shows the practical consensus of “no prestress is uneconomical”.

For the prestressed concrete composite slab of 4-side supported steel pipe truss with length width ratio not greater than 3, it should be designed as two-way slab.

This issue introduces: steel tube truss prestressed concrete composite slab.

The prestressed concrete composite slab of steel tube truss can be designed as one-way slab or two-way slab according to the structure of precast base plate support and the length width ratio.

In the design stage, the technology follows the design principle of “equivalent to cast-in-situ”, and truly realizes the connection of performance and cost between composite floor slab and cast-in-situ floor slab; Because pk3 plate technology can realize “no reinforcement and plate joint”, so as to realize “design standardization and modularization”, which is the key to “cost reduction and efficiency increase”.

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Hot rolled ribbed steel bars or hot-rolled plain round steel bars should be used as the stressed steel bars and structural steel bars in the laminated layer.

The thickness of prestressed concrete precast bottom plate of steel pipe truss shall not be less than 35mm; When the span is not less than 6.6m, the thickness of precast base plate shall not be less than 40mm.

Steel tube truss prestressed concrete composite beam technology (pkl composite beam for short) is the application extension of pk3 plate, which can be “produced in line” with a variety of products such as pk3 plate.

The laying length of prestressed concrete precast bottom plate of steel pipe truss shall meet the following requirements: when pouring with concrete beam or concrete shear wall at the same time, the extension into the beam or wall shall not be less than 10mm; When placed on steel beam or precast concrete beam, it shall not be less than 40mm; When placed on the load-bearing masonry wall, it shall not be less than 80mm; When the concrete ring beam is set on the load-bearing masonry wall and tied with beard reinforcement, the laying length shall not be less than 40mm..

The steel consumption and concrete consumption are reduced by about 40%.

When calculating the bearing capacity of two-way composite plates under uniformly distributed load, the influence of close fitting integral joints between precast bottom plates can be ignored.

The grouting material in the steel pipe should be micro expansion high-strength mortar, and the standard value of compressive strength should not be less than 40MPa.