IS 16231:2019 glass wind load calculator

What GlassLoad.com checks under IS 16231:2019

• Glass: annealed, heat strengthened and toughened glass, laminated glass of two sheets of equal thickness with a 0.38 mm PVB interlayer, or insulating glass, at the standard nominal thicknesses that have a column in Tables 6 to 14. An insulating unit is checked by its thinner pane, with no load sharing and no cavity pressure.
• Support: four edges, two opposite edges, or three edges, which is checked as two edges spanning along the unsupported edge as clause 7.4 allows. The longer side is limited to 4 m (clause 5.2 b).
• Pressure: you enter the net design wind pressure Pnet, the ultimate limit state pressure of clause 5.4, up to 10 kPa. GlassLoad.com does not work out wind pressure; take it from IS 875 (Part 3). It applies no load factor to the value you enter.
• Strength: the allowable area A_allow of a four edge pane, or the allowable span b_allow of a two edge pane, from the constants fitted to Tables 6 to 14, with the caps of the standard. The report gives the ratio of your pane to the allowable value and the capacity pressure Pcap.
• Deflection: the deflection at the centre from the formula of Annex C against the limit of clause 7.6.2 c, the smaller of the shortest span over 60 and 19 mm for monolithic glass, and the shortest span over 90 and 19 mm for a double glazed unit. The pressure Ps defaults to Pnet. The deflection has its own verdict. The standard deems glass that complies with Tables 6 to 14 to meet its deflection limit (clause 7.6.1).
• Second methods: the printed relation of clause 5.3, and the plate solver of GlassLoad.com against the design stress of Table 15 (clause 7.7), shown in the method panel against the table value.
• Minimum thickness finder: the thinnest standard thickness that passes strength and, when you ask for it, deflection.

Where the standard is unclear

Where IS 16231 leaves a point open or prints a value that does not agree with its own formula, GlassLoad.com says so in a warning that names the gap and the reading it used. Examples are the deflection of Annex D, the laminated and insulating glass deflection thickness, and the aspect ratio rule of clause 5.2 c. Heat strengthened glass on two or three edges is not checked, because the printed Table 14 is unclear.

What is not covered yet

• Human impact and safety glass selection (Part 4), fire resistant glass (clause 8), seismic load (clause 5.6), imposed and point loads (clauses 5.7 and 5.8.2) and sloped glazing.
• Glass fins, structural silicone, frame and mullion deflection, setting blocks, glazing clearances, thermal stress and point supported glass.
• Heat strengthened laminated and toughened laminated glass, laminated glass with unequal sheets or an interlayer other than 0.38 mm PVB, and thicknesses without a column in Tables 6 to 14, such as 25 mm. The calculator says so and gives no result.
• The wind pressure helper of IS 875 (Part 3). You enter Pnet.

Run a check with IS 16231:2019

Open the calculator and pick IS 16231:2019 as the standard. See also the guides, how the calculation works and the questions and answers. Results are to be verified by a qualified professional.

Worked examples

This is the worked example of Annex D of IS 16231 (Part 3):2019 that GlassLoad.com can run. GlassLoad.com computed it from the printed inputs. The example has its own page with all the steps. All worked examples

• Annex D: Annealed glass, 1200 by 1800 mm, Pnet 1.75 kPa