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How Is Glass Bearing Capacity Calculated

1. Glass bearing state


Doors, Windows and curtain walls have two states under the action of wind pressure:


One is four-sided support, suitable for frame doors and Windows, curtain wall.


The second pair of side support, suitable for glass doors and so on.

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2. The glass is subjected to wind load calculation


A) find three sets of formulas from JGJ113


When the four sides are supported, Wk= 0.2alpha is the majority when t is equal to 6mm


When t> At 6mm, Wk= alpha (0.2 t1.6+ 0.8)/Amax minority


Wk=0.142 alpha t/L glass door when supporting the side


In the formula, Wk - wind load standard value kPa


Amax - the most large area glass ㎡


L -- glass allowable span m


T -- glass thickness mm


Alpha -- the adjustment coefficient


Glass adjustment factor


Glass type ordinary semi - tempered steel interlayer hollow wire embossing fireproof


The adjustment factor was 1.01.62.0~3.00.81.50.50.63.0~4.5


B) example calculation


The size of 4 steel +A+5 is 1200 x 1800, and the glass bearing capacity is used.


Formula: Wk = 0.2 a alpha


Calculation and values: Wk=0.2 x 1.5 x 41.8/1.2 x 1.8=1.68 kPa.


Analysis: in the combination of thin section and float, it is advantageous to calculate by thin slice; otherwise, the cost is high;


(2) assuming that the two pieces are equal, the outer is tempered, the inside is floating, and the other is not;


In JGJ102, the outside is made of steel and the lateral steel is calculated.


Example 2. The laminated glass with a thickness of 5mm on the outer layer of fireproof glass and 4mm thickness of the inner layer tempered glass with a size of 1200 by 1800, for glass bearing capacity?


Formula: Wk= alpha (0.2 t1.6+ 0.8)/Amax


Calculation and values: Wk=0.8 (0.2 x 91.6+ 0.8) /1.2 x 1.8=2.78kPa


Analysis: the carrying capacity is very large, but the main function is fire prevention and high cost.


The wind pressure adjustment coefficient of toughened glass and single piece of fire-proof glass should be determined by experiment.


Example 3. Adopt 15mm toughened glass, whose size is 800 x 2000mm door, for glass bearing capacity?


Formula: Wk = alpha 0.142 t/a L


Calculation and values: Wk=0.142 x 2 x 15/2.0


Analysis: the door is strict with glass and thick;


(1) for the longest side, 1.94kPa for the short side;


Glass breakage is mainly tension damage, not pressure damage, so bending is the main contradiction.

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3. The problems should be paid attention to in calculation


A) JGJ113-2003 is the same as the 97 calculation formula, but the parameters are slightly changed.


Example: toughened glass is changed from 1.5~3.0 to 2.0~3.0 and increased fireproof glass adjustment coefficient.


B) the curtain wall is still in the form of JGJ102- by - x.


C) hollow glass composed of tempered glass and float glass, and how to deal with the thickness of the two.


The outer steel and inner layer float method, when the two are equal, the alpha is 1.5; Thin inner thickness, thin slice, the problem is not large; When it's thin inside, it's hard to use.


D) sandwich glass when the conditions of use for more than 70 ℃, alpha adjustment coefficient decreased from 0.8 to 0.8, the south needs to pay attention to when using.


E) toughened glass, fireproof glass is a range of adjustment coefficient to, how to value, the best is provided by the manufacturer, or take small value advantage, including toughened to test to determine when combined with fire.


F) tempered glass, different from all over the world, the best glass manufacturers provide, and take economic responsibility.


Analysis: ANSI is a glass factory that provides parameter values and guarantees quality;


The steel glass has the problem of self - violence, and abroad is about 8%.


The steel glass also has assembly problems, the profile deformation problem, the glass flatness is 2 %, so the lower limit is advantageous.


G) the problem of glass calculation and the following items are not included in this scope, but should be noted.


Such as glass perturbed, glass thermal stress, glass gravity, glass clearance, glass thermal performance, underwater glass, etc.