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How to calculate the bearing capacity of glass
2018/11/13 09:27
[Abstract]：
der the action of wind pressure, doors, windows and curtain walls have two states:
One is four side support, which is suitable for framed doors and windows and curtain walls.
The two is two sides supporting, suitable for glass doors and so on.
2. calculation of wind load on glass
A) find three sets of formulas from JGJ113.
When t is less than 6mm, Wk=0.2 alpha is the majority.
When t>6mm, Wk= alpha (0.2t1.6+0.8) /Amax is few.
Two Wk=0.142 t/L glass door when supporting sides.
Type Wk, wind load standard value kPa
Amax -- the largest area of glass
L -- glass permissible span M
T -- glass thickness mm
Alpha - adjustment coefficient
Glass adjustment coefficient
Glass type ordinary semi tempered tempered sandwich hollow clip fire prevention
Adjustment coefficient 1.01.62.0~3.00.81.50.50.63.0~4.5
B) example calculation
For example 1, the size of 4 steel + A + 5 hollow glass with external toughening and internal floatation method is 1200 x 1800. How to calculate the bearing capacity of glass?
Formula: Wk=0.2 alpha
Calculation and value: Wk=0.2 * 1.5 * 41.8/1.2 * 1.8=1.68kPa.
Analysis: (1) the combination of toughened lamellae and float method is beneficial to slice calculation, otherwise the cost will be high.
(2) assuming that the two pieces are equal, the outer ones are tempered and the inner ones are floating.
3. JGJ102 stipulates that the outer side is tempered, and the outer side is tempered.
Case 2: Sandwich glass with 5 mm thickness of outer fire-proof glass and 4 mm thickness of inner tempered glass is adopted. Its size is 1200 x 1800. How to calculate the bearing capacity of glass?
Formula: Wk= alpha (0.2t1.6+0.8) /Amax
Calculation and value: Wk=0.8 (0.2 x 91.6+0.8) /1.2 * 1.8=2.78kPa
Analysis: 1. At this time, the bearing capacity is very large, but the main role is fire prevention, and the cost is very high.
2. The wind resistance adjustment coefficient of tempered glass and monolithic fireproof glass should be determined by experiments.
Example three, adopt 15mm toughened glass, whose size is 800 * 2000mm door, to find the bearing capacity of glass.
Formula: Wk=0.142 alpha t/L
Calculation and value: Wk=0.142 * 2 * 15/2.0
Analysis: (1) the door glass is strict and the thickness is large.
(2) the most unfavorable person for L is the long side and the short side is 1.94kPa.
Glass failure is mainly due to tension failure, not pressure damage, so bending is the main contradiction.
How to calculate the bearing capacity of glass
3. problems that should be paid attention to in calculation
A) JGJ113-2003 is the same as the formula of 97, but the parameters vary slightly.
Example: tempered glass is changed from original 1.5~3.0 to 2.0~3.0 and increased the adjustment coefficient of fireproofing glass.
B) the glass used for curtain wall is still in accordance with the regulations of JGJ102- * * *.
C) the insulating glass made of tempered glass and float glass, and how to deal with the thickness difference between them.
When the two sheets are equal, the alpha is 1.5; when the outer sheet is thin and the inner sheet is thick, the problem is not big; when the outer sheet is thin and the inner sheet is thin, the problem is not good.
D) When the operating conditions of laminated glass exceed 70 C, the adjustment coefficient of alpha is reduced from 0.8 to 0.6. Attention should be paid to the use of laminated glass in the south.
E) The adjustment coefficient of tempered glass and fireproof glass is a range. How to choose the value is best provided by the manufacturer. Otherwise, it is advantageous to take a small value, including the combination of tempering and fireproof.
F) toughened glass is supplied by the best glass manufacturer in different parts of the country, and should bear financial responsibility.