Analysis of the key points of the glass curtain wall and countermeasures!

The glass curtain wall is a beautiful and novel method of building wall decoration. It is a prominent feature of the modernist high-rise building era. However, if the glass curtain wall is not well built, it will bring a lot of problems. Today we will analyze the key difficulties of the glass curtain wall together. Countermeasures.

First, the problems of construction

1, the use of material quality does not meet the requirements

The glass curtain wall is exposed to the air and is exposed to sunlight and etching media. It is necessary to use materials that comply with the relevant regulations of the national regulations to ensure the quality of the project. However, in actual construction, there are many curtain wall aluminum profiles and beam walls that cannot reach the wall. Specification requirements. Some aluminum profiles use ordinary grade materials and the anodized film thickness is less than 15μm, which does not meet the requirements of anti-corrosion; some engineering requirements require tempered glass, but semi-tempered or ordinary coated glass is used, the glass strength is insufficient, and there are safety hazards; Some of the engineering opening fans use stainless steel sliding supports with insufficient stiffness, which can easily cause serious deformation.

2, the quality of component production does not meet the requirements

The quality of component fabrication does not meet the requirements, which is an important reason for the unqualified construction quality of glass curtain wall. If the cutting precision of aluminum alloy profiles is poor, the assembly clearance of adjacent components is too large or too small; after the curtain wall glass is cut, it is easy to cause corner stress concentration to break the glass due to the chamfering process at the end. Some hidden frame glass curtain walls use the method of glue on the construction site, but there is no purification measures, which can not guarantee the relative humidity and temperature requirements, and can not avoid the pollution of the structural glue and glass bonding, it is difficult to ensure the production quality.

3. Problems with quality assurance data

Most glass curtain wall projects have problems such as incomplete data, irregularities, and many missing items. For example, there is no commodity inspection report for imported materials, some structural rubber materials have no valid period certificate, and no compatibility test report; most projects lack aluminum profiles. The quality certificate and high-precision index and oxide film thickness test prove that there is a lack of factory seal certificate for building sealing materials and fireproof materials; some concealed engineering acceptance sheets lack detailed records of fire protection nodes, lightning protection nodes and active joint nodes.

Second, the quality problems and prevention measures often encountered in construction

In view of the various problems existing in the above-mentioned construction, the following mainly proposes some prevention and control measures for the quality problems often encountered for reference.

(1) Leakage and deviation of the embedded parts of the curtain wall

1, the cause analysis

1) When constructing the main body of the civil works, the unit for glass installation is still determined, and it is likely that it cannot be pre-buried due to the design drawings of the embedded parts of the curtain wall.

2) The original design of the building does not consider the glass scheme. Later, it was decorated with a glass curtain wall, and there were no embedded parts in the structure.

3) In the construction of the main building, no fixed measures were taken for the embedded parts, and displacement occurred in the concrete pouring and vibrating.

2, the processing method

1) Before installing the glass curtain wall, the main body without the embedded parts must first determine the specifications and methods for the supplementary parts. It must be studied and determined by the design, civil engineering and installation units. It is not possible to use all the expansion bolts to connect with the main body. A layer of anchor connection should be added every 3~4 layers, and the expansion bolt can only be used as a partial additional connection measure. The expansion bolts used should be in a shear state.

2) For the problem of misplacement of embedded parts, it is necessary to check the misalignment of the embedded parts first and then correct the axes. If the deviation exceeds 20mm, splicing measures should be taken; if the recess is greater than 10mm, the steel plate must be repaired to the specified elevation before installation.

3. Preventive measures

1) Prior to embedding, the embedded parts should be covered with special technology to ensure the specifications, model and position of the embedded parts are correct, and the displacement in the vibrating is prevented to ensure the installation quality of the embedded parts.

2) Where a project with a glass curtain wall is designed, the installation unit shall be implemented during the civil construction and the location design of the embedded parts shall be provided. Pre-embedded pieces of embedded installation must have a person in charge, and at any time for the concealment project acceptance. The placement of concrete must be carefully inserted and compacted, and it must not touch the embedded parts to ensure the position of the embedded parts is accurate.

(2) Unsatisfactory anchorage of connectors and embedded parts

1, the cause analysis

1) When the connection piece and the embedded part are connected and handled, no treatment is performed according to the large sample drawing, some of them do not even have a large sample drawing at all, and construction is only based on past experience.

2) The welding quality of the joint and the anchorage of the embedded part is not good, and the design requirements and specifications are not met.

2, the processing method

1) Special attention should be paid to the anchoring of connectors and embedded parts, which is the key to ensuring the quality of glass curtain walls. When the connection is not found to meet the design requirements, it shall be reinforced and repaired according to the situation, and reworked if necessary.

2) If the height and width of the weld are insufficient, or there are defects such as slag and burns, it must be handled carefully. Please have experienced senior welders responsible for repair welding and reinforcement.

3. Preventive measures

1) When designing the glass curtain wall, draw a large sample of the joints for each joint, so that the workers can construct according to the drawings, and the technical requirements for the specifications, models and welds of the materials should be indicated.

2) When anchoring or welding between the connecting piece and the embedded part, it should be installed strictly according to the requirements of the specification. The height, length and width of the welded joint should be determined by design calculation.

3) The welder should pass the examination and be certified to work. The quality inspection of welded parts shall meet the following requirements: 1 When the weld is affected by heat, there shall be no defects such as cracks, pores and slag inclusions on the surface; 2 the undercut depth of the weld shall not exceed 0.5 mm, and the total length of the undercut on both sides of the weld It should not exceed 10% of the length of the weld; 3 weld geometry should meet the design requirements.

Third, the component installation joint leakage gasket

1, the cause analysis

1) If there is no spacer between the connection piece and the column, the component will easily produce electrochemical corrosion, which will have a certain influence on the service life of the entire curtain wall. The main reasons for the occurrence of leakage gaskets are as follows: First, the design of the node design diagram is marked at the end; second, the construction staff is leaking during construction; thirdly, the construction management personnel are not serious and have not corrected it in time.

2) 2, processing method

1) If no gasket is found between the connecting piece and the column, immediately fill the 1mm thick gasket of insulating heat-resistant hard organic material to prevent electrochemical corrosion of different metals.

2) When the elastic rubber gasket of the connecting piece at both ends of the column and the beam is not installed, it must be filled up and installed firmly.

3. Preventive measures

1) In order to prevent electrochemical corrosion of different metal material phase contacts, the specification stipulates that gaskets should be provided at the contact parts. Generally, a gasket of 1 mm thick insulating heat-resistant hard organic material should be used, and leakage or less discharge should not occur during installation.

2) Between the curtain wall column and the ends of the beam, in order to adapt to and eliminate the requirements of lateral temperature deformation and noise, the specification stipulates: at the joint, a rubber gasket with a rubber side and no rubber or a gasket made of nylon sheet should be provided. . Elastomeric rubber gaskets shall have a compressibility of 20% to 35%, shall be installed at the predetermined position of the column, and shall be securely installed, and the joints shall be tight.

Fourth, the phenomenon of leakage

1, the cause analysis

1) When designing the glass curtain wall, due to poor design considerations, the detail processing is not proper or not serious, and it is easy to cause leakage problems.

2) The quality of the rubber strip used is unqualified, or the specification does not meet the design requirements, resulting in uneven thickness of the rubber joint, thus forming a water permeation passage.

3) The construction of weather-resistant silicone sealant is not standardized, and the installation of the opening window does not meet the design requirements.

2, the processing method

1) First of all, we must carefully identify the cause of the leakage, and then take the appropriate treatment. If the water leaks due to the cracking of the sealant, the sealant of the shell and crack must be removed, the brush is wiped clean, and the qualified weatherproof silicone sealant is used to fill the tightness. After the test, there is no leakage. .

2) A waterproof strip should be added to the upper opening of the window.

3. Preventive measures

1) When designing the glass curtain wall, the drainage channel should be designed so that it can be discharged from the pipeline after collecting water, so that a large amount of water can be discharged from the curtain wall in time to reduce the chance of water penetration into the curtain wall.

2) Before filling the sealant, the contact should be wiped clean, and then the solvent seal can be used to fill the sealant. The thickness should be greater than 3.5mm and the width should be greater than 2 times the thickness.

3) The rubber strip should be selected according to the materials and specifications specified in the design. The inlay must be flat and tight. The glass installed on the opening window should be on the same level as the curtain wall. There should be no recession phenomenon.

Fifth, the fire compartment does not meet the requirements

1, the cause analysis

1) Some glass curtain walls were not designed with fire barriers in mind when they were designed, resulting in missing design items and rendering the glass curtain walls unable to fire.

2) Some floors are not connected to the beam at the beam. The position of the fire layer is not correct, and the node has no design.

3) The quality of fireproof materials used does not meet the requirements of the specification.

2, the processing method

1) After inspection, if the glass curtain wall is not provided with a fire barrier in the original design, the design unit and the construction unit shall research and supplement the fire protection program.

2) Some glass curtain wall fire barriers are closed with wooden materials and must be replaced with fireproof material anchors. When wood materials cannot be replaced, fireproof coatings should be applied to the surface of the wood material.

3. Preventive measures

1) When designing the glass curtain wall, do not miss the design of the fire compartment. When preliminarily designing the external facade division, the design of fire safety should be considered simultaneously and a large sample plot should be drawn. The specifications and anchorage requirements of the materials should be indicated on the map. 2) When designing the glass curtain wall, the arrangement of the beams is coordinated with the height of the floor. Generally, each floor is an independent fire zone. Beams and fire compartments should be placed on the floor.

3) The glass curtain wall and the gaps at the floor and partition walls shall be filled with fireproof or non-combustible materials, but the partition materials used for the fireproof layer shall not be in direct contact with the curtain wall glass. The gaps shall be filled with fireproof and heat-insulating materials and the surface joints shall be used. The sealant is tightly embedded.

Sixth, no lightning protection system

1, the cause analysis

1) When designing the glass curtain wall, the lightning protection system was not considered at all, and this part was omitted, which seriously affected the safety of the curtain wall.

2) Some construction workers are not familiar with the installation regulations of the lightning protection system, and cannot carry out the construction of the lightning protection system, resulting in failure to install or install.

2, the processing method

1) For the project that the lightning protection facilities are not installed on the glass wall, the lightning rod must be replenished and connected with the lightning protection system of the main structure. Generally, one layer is set every three layers to make the lightning protection system form the curtain wall system.

2) Carefully check the installed lightning protection system, including the specifications of its materials, connectors, lightning protection down conductors, grounding devices, etc., and its grounding resistance must not exceed 10Ω.

3. Preventive measures

1) There must be a lightning protection system design when designing the glass curtain wall. The construction drawings of the lightning protection system should be used in the construction so that the workers can construct according to the drawings.

2) The glass curtain wall shall be provided with flat iron or round steel lightning protection ring every three layers, and the lightning protection ring shall be connected with the lightning protection system of the main structure to make the glass curtain wall lightning protection system form its own system.

3) Materials for lightning protection rings, lightning protection lines, down conductors, grounding devices, etc. must meet the design requirements and lightning protection specifications.