I. Introduction

The open back-bolt dry-hanging stone curtain wall has a good visual effect, first-class performance and no noise. It is an ideal structural system. At the same time, it overcomes some shortcomings of steel pin type and groove type dry-hanging stone curtain wall, and has great advantages in safety, durability and replaceability.

In recent years, our company has undertaken a number of stone curtain wall projects. The back-bolt type open dry-hanging stone curtain wall has a complex process, high processing precision in the workshop, high on-site keel installation precision, large plate design, few grid lines, simple and clear appearance, and visual effect. good. Through the efforts of all parties, we organized technical personnel to tackle key problems for the construction quality control of the stone curtain wall with back bolts, and achieved good results. The facade effect is ideal, and it is well received by architects and owners.

2. Project Overview

The southern operation base project of China Unicom's mobile Internet industry is located in the R&D cluster area of ​​Dalian Road Headquarters in Yangpu District, Shanghai - Pingliang is connected to 12th neighborhood, west to Dalian Road, east to planning Jingxing Road, north to Huimin Road, south to Yulin Road. The total construction area is about 120,000 square meters. Frame shear structure, a total of 23 layers. The height of the building is 100 meters. The fire resistance level is one, the fire resistance limit of the floor fire layer is 2 hours, and the seismic fortification is 7 degrees. The cost of the curtain wall of this project is five thousand three hundred and ninety thousand yuan (53.9 million yuan). The owner is China United Network Communications Co., Ltd. Shanghai Branch. The construction scope includes all the projects of the outer curtain wall of the main building, doors and windows, glass railings, glass canopy, etc., which are mainly divided into glass curtain wall, stone curtain wall and aluminum plate curtain wall (the curtain wall includes floor fire blocking, internal insulation, etc.); doors and windows, shutters, Glass railings, steel structure glass awnings; steel components, connectors, etc. The curtain wall construction started on May 11, 2017, and the curtain wall was completed on October 31, 2018.

3. Scope of application

Scope of application: This open back bolted stone curtain wall construction quality control is suitable for stone curtain wall design, production and installation. The exterior wall decoration is mainly composed of large-area stone and hollow glass, supplemented by some vertical decorative strips.

4. Process principle

The open back-bolt dry-hanging stone curtain wall structure means that the joints of the back-bolt dry-hanging stone slabs adopt a non-gluing process, and the columns and the main structure of the stone curtain wall are connected by embedded parts and bolts, and then the horizontal keel is connected. One end is welded and the other end is bolted to the main keel; the stone material and the horizontal keel are connected with the aluminum alloy adapter through the back bolt. on the keel, so as to be transmitted to the main structure.

In the back-bolt dry-hanging method, the stone slabs form a self-connecting system, and the load is not transmitted between adjacent slabs, and the slabs and the skeleton form a movable connection, so that the slab has a large deformation space, and has good displacement performance and stability. Shock resistance. Easy to install, each panel can be removed and replaced individually. Use special equipment to drill and expand the holes on the back of the stone, and then install stress-free bolts on the back of the stone, which are connected to the skeleton through aluminum alloy clips.

There is a certain distance between the wall and the stone curtain wall. The air layer behind the stone curtain wall can flow smoothly through the slit, which can play a good heat insulation and sound absorption effect, so that the building can meet the good energy saving requirements and effectively reduce the use cost.

Five, the main performance and characteristics

(1) Good thermal insulation and energy-saving performance: the air convection on the back of it is used to reduce the heat exchange between indoors and outdoors, and the waterproof and thermal insulation structure of the inner layer further hinders the penetration of heat, thus achieving a significant thermal insulation effect. In summer, building cooling costs can be reduced, and in winter heating costs can be greatly reduced.

(2) Good seismic performance: The back-bolt structure belongs to the third generation of stone dry hanging technology, which is the most advanced technology in the world. . The back-bolt structure is to separate the stone panels independently, and each panel forms its own independent connection system. There is no load transfer between the adjacent panels, and the panel and the skeleton are still designed as active connections, which can ensure that the panels have enough space for displacement and deformation. , so theoretically, the back-bolt structure has better displacement deformation performance and seismic performance than other structures.

(3) Beautiful appearance: The seams of the stone slabs are not sealed with sealant to make them open visually. The seams have a depth, a strong sense of assembly and three-dimensional sense, and the exterior decoration effect is good. Because no sealant is used, no glue oil seeps out and corrodes the stone. And absorb dust, keep the surface of the curtain wall clean for a long time, and improve the exterior decoration effect.

(4) Meet the functional requirements of modern buildings: There is no glue application on the construction site for traditional curtain walls, and the joints of stone slabs are mostly waterproof and sealed with silicone weather-resistant sealants. The impact of workers' skills is great, the construction quality cannot be guaranteed, and it is easy to pollute the stone. The open back bolt dry-hanging stone curtain wall adopts the internal waterproof structure of the structure to ensure the needs of rainwater leakage and thermal insulation and energy saving, so there is no need to carry out glue operation on the stone slab joints, which is also different from the current curtain wall "no glue at the construction site". work" in line with the overall development trend.

(5) Excellent safety performance and structural durability: the size of the plate is not determined by the bearing capacity of the anchor bolt, but by the bending resistance of the plate. The back of the stone is connected by stainless steel back bolts, which have high connection strength and save about 30% of the strength value. Meet the service life of the entire exterior wall decoration and the service life of the entire building.

(6) Good repair performance: damaged stone slabs can be replaced at any time.

Six, construction quality control points

(1) Technical preparation and material ordering

Understand and deepen the original architectural drawings, and combine the original structural drawings to measure and measure the structural walls, frame columns, and roof beams, and draw the curtain wall lofting drawings. Confirm the partition effect of the curtain wall stone, and calculate the amount of materials needed. Submit a stone purchase order according to the number specified in the set-out drawing. Strictly check the submitted quantity, specifications and quality standards during delivery, and do a good job in the protection of finished products.

(2) Measurement and pay-out

Re-measure the axis control line and elevation line provided by the structural construction unit. After confirming that they are correct, combine the positions and axes of the horizontal and vertical keels given in the drawings to determine the positions of the horizontal and vertical keels and the stone curtain wall. First measure from the middle to the two ends, and then check the size from the two ends to the middle. The released horizontal and vertical keel position line errors should meet the design requirements.

(3) Keel production and installation

1. Steel column installation

The column is made of steel square column. Due to the large amount of installation work and high construction precision requirements, the steel square pass column occupies an extremely important position in the entire curtain wall installation process.

2. Steel beam installation

The beam adopts angle steel beam. Measure the positioning line of the beam on the steel column, and use the level to measure the elevation of the steel beam. Fastener-type steel pipe scaffolding is used to install angle steel beams, and the steel beams are fixed on the steel columns according to the design requirements.

The angle steel beam and the steel square pass column are fixed by welding. Therefore, the finished decorative surface below and adjacent to the finished decorative surface should be protected during the welding operation. Symmetrical welding should be used during welding to reduce the deformation caused by welding. After checking the quality of the welding seam, all welding points and welding seams shall be treated with slag removal and anti-corrosion treatment, and the welding acceptance and anti-corrosion acceptance shall be carried out in time.

(4) External wall insulation and waterproof construction

The external wall insulation adopts the standard thick rock wool board according to the energy-saving design requirements. The connection between the thermal insulation layer and the structural layer is fixed with expansion bolts, and the gap between the board and the board is bonded with a special tape.

(5) Installation of aluminum alloy pendant

The stone processing should meet the requirements of the construction schedule. After the processing is completed, it should be packed according to the number specified in the lofting drawing, and a packing list should be attached. The stone panels shall be transported to the vicinity of the construction area according to the construction requirements and according to the list, and shall be placed in an orderly, stable and reliable manner to prevent overturning. When handling stone, safety precautions should be taken, and foam or wooden pads should be placed under it.

(6) Stone panel installation

Install the anchor bolts and aluminum alloy pendants on the stone. After testing the quality of the stone surface, lift the plate to the installation site.

Before stone installation, pull out the theoretical finish surface with steel wire so as to control the in and out position of the stone slab installation and ensure the flatness of the stone plane after installation.

When installing, directly buckle the aluminum alloy pendant on the keel, and then adjust the height through the fine adjustment of the top wire on the top of the pendant to ensure that the height difference between the stone joints meets the requirements of the acceptance specification. Stone installation is carried out from bottom to top, and it is carefully operated. The level, verticality and flatness of each hanging slate are checked and adjusted in time.

7. Quality requirements and acceptance criteria

(1) The variety, specification, performance and grade of the materials used in the stone curtain wall project should meet the design requirements and the current national product standards and engineering technical specifications.

(2) The shape, facade division, color, gloss, pattern and pattern of the stone curtain wall shall meet the design requirements.

(3) The number, depth, location and size of stone holes and grooves should meet the design requirements.

(4) The position and quantity of the embedded parts and the post-embedded parts on the main structure of the stone curtain wall and the pulling force of the post-embedded parts must meet the design requirements.

(5) The connection between the metal frame column of the stone curtain wall and the embedded parts of the main structure, the connection between the column and the beam, the connection between the connector and the metal frame, and the connection between the connector and the stone panel must meet the design requirements, and the installation must be firm.

(6) The surface of the stone curtain wall should be smooth, clean, free from pollution, defects and cracks. The color and pattern should be consistent, without obvious color difference and repair marks.

(7) The stone joints should be horizontal and vertical, with uniform width; the yin and yang corner stone slabs should be pressed in the correct direction, and the joints of the edges of the slabs should be straight; the thickness of the convex and concave lines should be the same, and the upper and lower openings should be straight; the openings and grooves on the stone panel The sides should be cut and matched, and the edges should be neat.

(8) The sealant joint of the stone curtain wall should be horizontal and vertical, the depth is consistent, the width is uniform, smooth and straight.

(9) The drip line and flowing water slope on the stone curtain wall should be correct and straight.

(10) The cover and repair of the hidden nodes of the stone curtain wall should be firm, neat and beautiful.

8. Conclusion

The construction quality control of open back bolted stone curtain wall has greatly improved the seismic resistance and wind pressure resistance of the curtain wall, with high stability and strong safety. The stone slab installation is convenient and flexible during the construction process, which also verifies the open back bolt. The market development prospect of dry-hanging stone curtain wall must be broad.

The quality control of the open back bolted stone curtain wall construction avoids the currently commonly used steel pin type and short groove type stone dry hanging process in the stone boundary slotting, which is easy to cause shearing and bending damage at the root of the stone end face groove wall panel ridge. More effectively ensure the safety of dry hanging stone curtain wall.