Read a glass curtain wall safety appraisal

After more than 30 years of development, the domestic building curtain wall has established a national industry standard system and completed a huge amount of engineering practice. With the continuous development of the economy, the annual output value of the building curtain wall industry shows a steady growth trend, but in recent years, the glass curtain wall safety accidents have frequently occurred, and the "fashion label" in these cities seems to have become the "invisible killer" in the sky, at the same time, people's attention to the safety testing and maintenance of the glass curtain wall is far from enough, exposing many safety problems. It also caused serious social impact such as property loss and personal injury to varying degrees.

01

Overview of glass curtain wall

Glass curtain wall is divided into frame (open frame, hidden frame, semi-hidden frame) glass curtain wall, point support glass curtain wall, all glass curtain wall and unit glass curtain wall according to the different structure.

① Frame glass curtain wall

Frame supported glass curtain wall is a glass curtain wall supported by a metal frame around the glass panel.

② Point support glass curtain wall

Point-supported glass curtain wall: The curtain wall glass is fixed with stainless steel lapel claws, and the stainless steel lapel claws are welded to the shaped steel keel. The four corners of the curtain wall glass are processed in the glass manufacturer to complete 4 round holes with stainless steel lapel claws, and each claw is connected with 1 hole of 1 piece of glass, that is, 1 stainless steel lapel claws are connected with 4 pieces of glass at the same time, or 1 piece of glass is fixed on 4 stainless steel lapel claws.

③ All glass curtain wall

Glass curtain wall: glass curtain wall composed of glass ribs and glass panels. This kind of glass curtain wall has no metal skeleton from the facade, and the finishing materials and structural members are glass materials. Because of its large glass finish, so that the curtain wall has greater permeability, so it is often used in buildings.

④ unit glass curtain wall

Unit curtain wall refers to the basic unit of curtain wall structure made of various wall panels and supporting frames in the factory, and is directly installed on the main structure of the building curtain wall.

02

Analysis of safety problems of glass curtain wall

The existing curtain wall safety problems are mainly divided into five aspects: glass curtain wall damage, metal connector failure, adhesive material failure, leakage, poor fire resistance and other problems.

1. Damage of glass curtain wall

The damage of glass curtain wall is divided into self-explosion (material and use reasons) and damage caused by natural disasters or sudden accidents, which can easily lead to "glass rain" due to burst and fall.

2. The metal connector is faulty

Local wall panels or connecting components appear abnormal deformation, falling off, cracking, resulting in the failure of connecting parts, which can easily lead to panel fall accidents.

3. The bonding material fails

Due to the long-term adverse factors of the natural environment, the structural adhesive is easy to age and fail, resulting in the fall of the glass curtain wall. Then in the design should be as far as possible to use open frame or semi-hidden frame glass curtain wall, because even if the structural adhesive failure, due to the support and constraints of the frame, it will greatly reduce the chance of glass fall.

4. Leakage problem

The unreasonable design of the open fan sink, the loose sealing of the window sash and the broken glass panel will lead to leakage, which will lead to rust of the hardware and aging of the structural glue, and affect the structural stability of the curtain wall.

5. Poor fire resistance

Glass curtain wall is a non-combustible material, but in the face of fire, it can melt or soften, in the fire only a short time will occur glass broken, so in the architectural design to fully consider the fire requirements of the building

Therefore, strengthening the safety management of the existing building curtain wall, regular inspection and testing identification, timely detection of problems and taking the necessary measures are crucial to ensure the safe use of the building curtain wall.

03

The necessity of safety appraisal of glass curtain wall

With the continuous aging of the main materials and main components of the curtain wall, if it is not checked and maintained in time, it will form a larger security risk.

According to the relevant provisions of the "Technical Specifications for Glass Curtain Wall Engineering", a comprehensive inspection of the curtain wall project should be carried out one year after the completion and acceptance of the curtain wall project, and then a comprehensive inspection should be carried out every five years and a safety evaluation should be carried out every ten years.

04

Glass curtain wall safety appraisal content

1. Basic investigation

Consult drawings and information to master the use of glass curtain wall, such as construction, maintenance, damage, use environment and whether it has suffered disasters;

Second, material inspection

(1) Aluminum alloy profiles

Mainly check aluminum alloy profile specifications, wall thickness.

(2) Glass

Mainly check the specifications, varieties, thickness, appearance quality and edge treatment of the glass, and detect the surface stress of the glass on site to determine the toughening state of the glass.

(3) weather resistant sealant

Check whether the sealant is full, flat and dense, and whether there is cracking, foaming, softening sticky, pulverizing, degumming, discoloration, fading and chemical precipitates.

(4) silicone structural sealant

Check the appearance quality, injection size, injection quality and bonding quality of the structural sealant, and carry out the stripping test and tensile bond strength test between the structural adhesive and the substrate.

(5) Hardware parts and accessories

Mainly check the material, thickness, appearance quality, surface corrosion (rust) and aging of non-metallic parts in accessories.

Third, installation and connection check

(1) Glass installation

Check the installation of the glass panel.

(2) The beam is connected with the column

Check the connection between the beam and the column.

(3) Check the connection with the main structure

Check the connection between the curtain wall and the main structure of the building. Check the specifications and quantity of connectors, insulation sheets, and fasteners. Where anchor bolts are used for anchoring, check the type, specification, quantity and layout of anchor bolts.

(4) Inspection of fire protection structure

Check whether the fireproof structure is set, and check the laying and thickness of the fireproof cotton.

Fourth, open the window inspection

Check the function and installation firmness of the hardware fittings for opening Windows. Measure the opening section specification, observe the type, quantity and position of the recording window handle. Check the appearance quality of the structural sealant for opening Windows.

5. Calculation of bearing capacity

According to the field test and relevant standards, the force analysis of the curtain wall structure system is carried out to check the bearing capacity of the components and their connections.

6. Identification, rating and handling suggestions

The data and data of inspection, detection and verification are comprehensively analyzed and comprehensively evaluated to determine the safety appraisal level of the hidden frame glass curtain wall. Submit the problems found in the curtain wall appraisal process, and make recommendations for treatment.

Under the rapid growth of the economy, China has been the big country to use the building curtain wall, and people are gradually improving the demand for building curtain wall, but because the use of early building curtain wall has reached most of the service years, various problems will occur, causing the use of curtain wall to have security hidden trouble.

The inspection and testing of the existing glass curtain wall structure, the timely discovery of existing problems, maintenance and treatment will help to extend the service life of the glass curtain wall and improve the safety performance of the glass curtain wall.