How to choose safe exterior building shading products for high-rise buildings 2

MEDIA CENTER

Oct 13th, 2023

External sunshade project implementation, the application of the product in addition to the “General Requirements for Architectural Sunshade” JG/T 274-2010 standard provisions of the relevant performance evaluation (including sunshade coefficient, appearance quality, operational performance, mechanical durability, load-bearing capacity, etc.), the more important is the ability to resist wind, snow load calibration.

The safety performance of building external sunshade devices is the most important and concerned issue in the engineering world. Wind load is the most common form of load in the use of external sunshade devices, and it is also one of the factors most likely to cause safety accidents, so wind resistance is the most important one in the key index of external sunshade products. At the beginning of the design of the sunshade project, according to the basic wind pressure of the project location, climate, geographic environment, building height, and other architectural features, focusing on the consideration of the wind load of the height of the wind pressure changes, the body type coefficient and lateral gusts of wind and other conditions brought about by the impact.

Safety performance is the most important element to be emphasized in the design, construction, acceptance, and use of external sunshade products. Fig. 7 and Fig. 8 show the case of roller shutter windows installed in high-rise buildings that were not fully closed (or closed), and the shutters were damaged or derailed and deformed when strong winds struck.

Fig. 7 and Fig. 8 Damaged external sunshade roller shutter window

General Provisions

(1) The wind resistance performance level of external sunshade products shall meet the requirements of the industry standard “Technical Specification for Building Sunshade Engineering” JGJ 237-2011 and “General Requirements for Building Sunshade” JG/T 274-2010.

(2) The grade of external sunshade products should meet the design requirements. When there is no clear design requirement, the general standards are as follows: the wind resistance grade of the buildings below 6 floors should not be less than 4 levels (i.e. the safety test pressure of the roller shutter products is more than 600 Pa, and that of the metal blinds is more than 250 Pa); the wind resistance grade of the buildings from 6 to 11 floors should not be less than 5 levels (i.e. the safety test pressure of the roller shutter products is more than 900 Pa, and that of the metal blinds is more than 900 Pa). (i.e. the safety test pressure of roller shutter products is more than 900Pa, and the safety test pressure of metal blinds is more than 400Pa); the wind resistance level of buildings higher than 11 floors should not be less than level 6 (i.e. the safety test pressure of roller shutter products is more than 1200Pa, and the safety test pressure of metal blinds is more than 600Pa).

(3) According to the wind resistance grading standard of sunshade products, the wind resistance of external sunshade metal blinds should be no less than 4 levels, and the external sunshade roller shutters (metal hard roller shutters) should be no less than 5 levels.

Main control items

(1) When external sunshade products are applied to residential buildings of 27m and above or other buildings of 24m, effective windproof side buckle measures (or other devices with equivalent functions) shall be set up;

(2) When the external sunshade products are applied to high-rise buildings, especially those with a height of more than 90m, the wind speed sensing system shall be configured. (The sunshade device equipped with wind speed sensing controller, wind resistance is determined according to the sensing control range, such as the sunshade device is put away when controlling 6 levels, and the standard value of wind load can be taken according to the value of 6 levels of wind pressure).

Grading of wind resistance of external sunshade products

External sunshade metal blinds products wind pressure performance grading (see Table 1) based on the standard: “Architectural sunshade metal blinds” JG/T 251-2009.

Table 1 external sunshade metal blinds wind pressure performance grading

Architectural sunshade roller shutter products wind pressure performance grading (see Table 2) based on the standard: “Architectural sunshade hard roller shutter” JG/T 443-2014.

Table 2 External sunshade metal blinds wind performance rating

Wind load calculation of external sunshading device

Calculation formula for the standard value of wind load perpendicular to the surface of the building:

Basic wind pressure W0 can be “windows and doors, curtain wall wind load standard value” formula correction coefficient has been involved in the calculation, do not have to find out separately. W0 data checking through the three parameter values corresponding to a belonging to the region; two ground roughness types; and three distances from the ground height. Ground roughness type:

A: refers to offshore sea surface and islands, coasts, lakeshores, and desert areas;

B: fields, villages, jungles, hills, townships and city suburbs where houses are relatively sparse;

C: urban areas with dense built-up areas;

D: urban areas with dense buildings and high houses.

Wind Pressure Resistance Test of External Sun Shading Devices

External sunshade project application of external sunshade metal blinds and roller shutters (metal hard roller shutters) are mostly used in high-rise buildings, and their ability to resist wind pressure needs to be verified and tested. The test method is based on the standard of “Test Method for Wind Resistance of Building Sunshade Products” JG/T 239-2009, and the standard of wind resistance of external sunshade metal blinds is “General Requirements for Building Sunshade” JG/T 274-2010.

(1) Common window width specifications for external sunshade metal blinds testing, external sunshade metal blinds specifications: 1500mm × 1500mm (width × height). The conclusion of the test is that the wind resistance performance reaches level 4 (the normal use of the curtain is not affected, and no permanent deformation is produced), and the resistance to wind load capacity is 400N/m² (1.5P=600N/m²).

(2) The wind resistance of external sunshade roller shutter window is assessed by “Architectural Sunshade Hard Roller Shutter” JG/T 443-2014. Ordinary window width specifications for external sunshade roller shutter window testing, sunshade hard roller shutter specifications: 1200mm × 1500mm (width × height). The test concluded that the wind resistance performance of 5 (the normal use of the roller shutter is not affected, did not produce permanent deformation), resistance to wind load capacity of 600N/m² (1.5P = 900N/m²).

(3) ultra-wide specification window sunshade roller shutter window test, sunshade hard roller shutter specifications: 2620mm × 2000mm (width × height), the test concluded that the wind resistance performance to meet the standards of level 3 (safety performance is significantly reduced), resistance to wind load capacity of 200N/m² (1.5P = 300N/m²).

From the wind load test of external sunshade products, it is concluded that the wind resistance of external sunshade products decreases greatly with the increase of width size and area of sunshade products, and the reliability is weakened. In engineering practice, the wind safety performance of external sunshading products applied on high-rise buildings should be highly emphasized by designers and related engineering technicians.

Measures to improve the safety of external sunshading devices

Design Measures

Pay attention to analyze the geographical location of the application area, climate characteristics, building height and other architectural characteristics, to determine the main impact of various factors on the use of external sunshading device, the design of external sunshading products for ultra-wide specifications of the window split processing, to ensure safety and reliability. Adoption of motorized form of external sunshade products, set wind speed sensing system, can add more security to the use of external sunshade products.

Windproof construction measures for external sunshade products

Due to the different structure of the products, the wind load safety performance calibration of external sunshade metal blinds and external sunshade roller shutters (hard roller shutters) should be different, which is reflected in the design of the correction factor added to the formula. Comparison of “sunshade device wind load correction coefficient” two sets of data, showing that the external sunshade roller shutters (hard roller blinds) security requirements than the requirements of the external sunshade metal blinds.

External sunshade roller shutters (hard roller shutters) using windproof structure to improve safety, external sunshade hard roller shutters windproof structure is a combination of structures (Figure 9, Figure 10), nailed into the windproof side buckle of the hard roller shutter curtain sheet and windproof track with the use of greatly improved to prevent the hard roller shutter as a whole out of the track of the function of the function of the function to reduce the probability of failure of the hard roller shutter derailment, increasing the use of the product safety performance.