Problems in curtain wall construction of building 1

It is precisely because of "design lag" and "poor audit" that the design quality of curtain wall engineering is hard to guarantee. Judging from the inspection results of national curtain wall projects in recent years, the following are common problems in design:

1. 1 embedded parts: some engineering bodies have not designed embedded parts, so they have to use expansion bolts and chemical bolts to remedy them; Some have embedded parts, but the specifications, welding and anchoring length of the embedded parts do not meet the requirements of the specification.

1.2 column and beam: the mechanical calculation model of the column does not conform to the engineering practice, the calculation or application of the section characteristic parameters of the column and beam is wrong, and even the section shape of some sections does not meet the stress requirements; The column is designed as a compression member (it should be designed as a tension member according to regulations); Check the strength of the rod, but don't check its stiffness; Not according to the most unfavorable frame and maximum span for checking calculation.

1.3 connection between curtain wall and main body: the welding strength between support and plate is not enough, and there is only one bolt at the connection, and the corner code is subjected to excessive bending moment, but it is not reinforced.

1.4 plate fixing part: the lower part of the concealed frame curtain wall plate is not provided with braces, the distance between the pressure plates is too large or the pressure plates themselves are not strong enough.

Fire protection and lightning protection: the thickness of waterproof cotton is insufficient or the fire partition is too thin, the fire protection nodes are not tight, and the lightning protection nodes at the expansion and contraction of the column are not handled properly.

2 building curtain wall construction quality control methods

2. 1 Necessity of early supervision of building curtain wall project

2. 1. 1 Compiling supervision rules: Compiling feasible supervision implementation rules according to engineering acceptance specifications and actual requirements.

2. 1.2 system review: before the start of construction, review the quality management system, technical management system and quality assurance system of the on-site project management organization of the construction unit, and review the qualification, technical and management level, previous construction achievements and post certificates of the personnel of special types of work of the construction unit.

2. 1.3 review of construction organization design: the supervisor should focus on the review of construction scheme, construction machinery and construction sequence, especially the engineering quality control and guarantee measures of key processes, mainly including installation procedures, machine installation, scaffolding, connection of iron code and embedded parts, installation and position adjustment of columns and beams, welding rust prevention measures, plate installation, fire-proof cotton installation, lightning protection system installation, weather-resistant sealant sequence, aluminum frame and glass protection.

2. 1.4 blue prints.the design and disclosure: the construction unit will draw the detailed drawings and structural calculations of the construction and sampling points according to the renderings and the actual geometric dimensions of the frame, and the blue prints.the design will be conducted after confirmation by the owner and the designer. The key points of the joint review of drawings are: whether the drawings meet the requirements of technical specifications; Whether the design conforms to the principles of safety, rationality and advanced technology; Whether the design meets the requirements of the construction unit; Whether the construction is convenient, reasonable and economical; Technical disclosure shall be made to the construction unit on the design intent, technical requirements, difficulties and quality assurance measures of key parts.

2. 1.5 raw material entry review: in order to make the curtain wall project safe and reliable, the curtain wall materials should meet the design requirements and the current national product standards and engineering technical specifications. In order to make the building curtain wall have enough weather resistance and durability, it is required that the metal materials used in the building curtain wall, except stainless steel and light metal materials, should be hot-dip galvanized and the aluminum alloy should be anodized. The test results of structural adhesive for building curtain wall should meet the requirements of the specification.

2. 1.6 Inspection and recheck of conditions before installation of processing, manufacturing and construction: the curtain wall can only be processed and assembled after checking the architectural design and construction drawing and adjusting the curtain wall before production, and obtaining the consent of the designer and supervisor. In order to ensure the quality of curtain wall, it is required that the main structure project should meet the basic conditions of curtain wall installation, especially the verticality of the main structure, the flatness of the external surface and the dimensional deviation of the structure, and must meet the requirements of Code for Construction and Acceptance of Reinforced Concrete Structures, otherwise corresponding measures must be taken before it can be carried out. In order to ensure the firm and reliable connection between curtain wall and main structure, the embedded parts connected between curtain wall and main structure should be buried according to the design requirements during the construction of main structure. The elevation deviation of built-in parts should not be greater than 10mm, and the position deviation of built-in parts should not be greater than 20 mm. ..

Curtain wall material is the material basis to ensure the quality and safety of curtain wall. Curtain wall materials can be classified into four types: skeleton materials, plates and sealing caulking materials. All materials must have certificates and quality guarantees, and some materials must also have reports, structural adhesive compatibility test reports and curtain wall performance test reports. No certificate or qualified test report, should resolutely put an end to the use.

2.2 Implement the quality acceptance system of each working procedure.

The construction of building curtain wall generally includes four key processes: the production of glass plate, the installation of curtain wall joint beam and column, and the installation of glass plate. For each of these four processes, strict inspection and acceptance system should be implemented according to the requirements of design or specification, and unqualified processes should be rectified or reworked until they are qualified. Manufacture of glass flat plate

In this process, we should focus on checking the environmental conditions of the production workshop, and the indicators such as temperature, humidity, ventilation and dust in the workshop should meet the requirements of specifications or design; Check whether the specifications, dimensions and appearance quality of glass or metal hanging plates meet the specifications or design requirements; Check the production date and validity period of structural adhesive to determine whether it is used within the validity period; Check whether the thickness, width and quality of structural adhesive meet the specifications or design requirements.

2.2.2 Installation of curtain wall nodes

The quality control of this process focuses on the embedding quality control of curtain wall embedded parts during civil construction. Supervisors should urge curtain wall designers and construction units to strengthen contact and cooperation with civil engineering units in advance, so that the embedding position and quality of curtain wall embedded parts can meet the requirements of curtain wall design or specification, which is an important quality control link related to the construction and installation quality of the whole curtain wall project. In addition, the welding quality of embedded iron pieces and connecting angle codes, and the connecting quality of upright posts and connecting angle codes are strictly inspected and controlled.

2.2.3 Installation of beams and columns

This process focuses on checking whether the horizontal line of vertical beam installed in the column and the specifications and dimensions of curtain wall frame meet the requirements of specifications or design; Check and control the connection quality between beam and column.

2.2.4 Installation of glass plate

This process focuses on the inspection of the fixed connection quality of glass plates and the sealing quality of sealant. The sealant caulking construction should be carried out under suitable climatic conditions, and technicians should prevent bubbles from appearing during construction and ensure that the thickness of sealant caulking is controlled within the range required by the specification.

2.3 Supervise and assist the construction unit to establish a technical personnel guarantee system.

The construction unit shall designate a special person to be responsible for the inspection and acceptance of the construction and installation quality, and analyze and study the quality problems found in time with the on-site construction personnel, find out the reasons and correct them. In the absence of inspection and acceptance, quality managers and supervisors combine self-inspection, mutual inspection and final acceptance to ensure that the construction quality is under control.

2.4 do a good job in fire prevention and lightning protection of curtain wall.

The curtain wall shall be made of incombustible and flame retardant materials, and materials with moisture-proof, heat insulation and fire prevention measures shall not be in direct contact with the glass.

Curtain wall should meet the requirements of fire protection grade. Fire prevention measures should be taken for the gaps between the window walls between curtain walls and the floors and partitions. The fireproof board shall be made of metal plate not less than 1.2mm, and the lap joint shall be sealed with fireproof sealant.

The wind pressure deformation, rainwater leakage and air permeability of curtain wall must be tested according to the current national standard (CB/T 1526- 15228) and meet the requirements of design and specification. If the design thinks it is necessary, the indexes such as heat preservation, sound insulation, earthquake resistance, fire prevention and lightning protection should also be tested.

Curtain wall should meet the requirements of lightning protection level. Curtain wall should have its own lightning protection system. Its grounding resistance value should be less than1Ω, the beam located at the equalizing ring must be connected with the column connected with the equalizing ring, and the horizontal distance of the column on the floor without equalizing ring must be connected with the equalizing ring every1Ω. The cross section of the connected material should meet the lightning protection requirements, and its grounding resistance value should be less than or equal to 4Ω.

Due to the particularity of curtain wall engineering, its quality supervision mainly depends on pre-control and in-process control. Therefore, supervisors must be fully familiar with the whole construction process, put forward quality control and inspection standards in advance, and supervise the construction unit to strictly abide by and implement them in order to achieve the expected control objectives.

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