Foreword

TCVN 7505:2005 was developed by the Technical Committee for Glass in Building Standards TCVN/TC 160, based on the draft by the Glass and Ceramic Construction Corporation, proposed by the Ministry of Construction, appraised by the Directorate for Standards, Metrology and Quality, and promulgated by the Ministry of Science and Technology.

1. Scope

This standard specifies the basic requirements for selecting and installing glass by type and allowable thickness for a given maximum area or maximum allowable area for a given thickness, in residential and public buildings, to ensure safety for users and structures.

This standard does not apply to single glazing with an area greater than 15 m² and a span greater than 4 m.

2. Normative references

TCVN 2737:1995 Actions and action effects – Design standard.

TCVN 4088:1995 Climate data for building design.

TCVN 7526:2005 Construction glass – Definitions and classifications.

3. Terms and definitions

The terms used in this standard are defined as follows:

3.1

door

A glazed barrier that opens by swinging or sliding, providing access to a building, hallway, or room, which may be framed or unframed.

3.2

double windows

A window consisting of two glazed sashes, installed in separate frames, fitted within the same window opening.

3.3

structural sealant

An elastic material used to securely bond partitions to a frame or base plate anchored to the floor surface.

3.4

stall board

A vertical structure, with a frame or base plate anchored to the floor surface, for securely attaching partitions.

3.5

tempered glass

A flat glass that has been specially heat-treated or chemically treated to induce high compressive surface and edge stresses substantially greater than those for heat-strengthened glass.

NOTE:

1) Tempered glass is not necessarily safety glass;

2) The heat or chemical treatment process significantly reduces the tendency of the glass to break under external forces or temperature changes;

3) After tempering, this type of glass cannot be cut, drilled, ground or further processed. Sandblasting, etching or other surface processing must be done before tempering.

3.6

tempered safety glass

A tempered glass that, when broken, disintegrates into small particles unlikely to cause injury to people.

3.7

heat-strengthened glass

A glass that has been specially heat-treated such that the compressive surface and edge stresses are between those of ordinary annealed and tempered glass.

3.8

double glazing

A glass unit consisting of two panes of glass with an air space or vacuum in between for sound insulation, thermal insulation or both (also called insulated glazing or insulated glass unit).

3.9

laminated glass

A glazing material consisting of one or more glass layers bonded to one or more other glass layers or clear plastic layers by means of one or more interlayers.

NOTE: Laminated glass may crack or break under sufficient impact, but glass fragments tend to adhere to the plastic interlayer rather than falling free.

3.10

laminated safety glass

A laminated glass capable of sustaining loads and, in the event of breakage, retaining broken pieces, maintaining residual integrity and reducing injury.

3.11

ordinary annealed glass

A glass that has been slowly cooled in the annealing phase of the manufacturing process to reduce residual stresses and tensions induced during cooling.

3.12

safety wired glass

A glass with a steel wire mesh embedded in it during manufacture to restrict and retain broken glass pieces, maintain residual integrity and reduce injury.

3.13

size

See descriptions in Figure 1.

3.13.1

glazing panel size

The actual size of the glass sheet.

3.13.2

sight size or daylight size

The size of the light transmitting opening excluding frame elements.

3.13.3

tight size or rebate size

The actual size of the rebate opening.

3.14

frame

A surround of wood, steel or other rigid materials along the entire length of each edge of the glass sheet to provide enhanced load-bearing capacity.

3.15

span

The visible dimension between supporting frames. For glass panels supported on all four edges, this dimension corresponds to the smaller of the sight sizes.

3.16

fin

A panel at the side of a glazing location.

3.17

aspect ratio

The ratio of the longer to shorter dimension of a glazing panel.

3.18

chair rail

A rigid bar or rail to protect the glass from human impact.

3.19

internal partition

An interior dividing wall or part of an interior wall inside a building not being a door, sidelight, shopfront or skylight.

3.20

shopfront

A partially or fully glazed frontage positioned at the entrance of a building for public access, with or without stallboard.

NOTE: Shopfronts include glazing to shop premises and public areas but do not include the upper story glazed façades of buildings.

Figure 1 – Description of sizes and rebates

4. General requirements

4.1 Material requirements

4.1.1 Glass materials

Glass materials used in civil engineering constructions include glass types classified according to TCVN 7526:2005.

The quality of each glass type shall conform to the respective technical standards for that glass type.

4.1.2 Classification of safety glass

– Group A safety glass: laminated safety glass and tempered safety glass;

– Group B safety glass: safety wired glass.

4.1.3 Other materials

Materials used in conjunction with glass during installation include sealants, glazing compounds, adhesives, setting blocks, spacers, paints etc.

4.2 Dimensional requirements

4.2.1 Glass thickness

For a given glass type and area, the glass thickness shall not be less than the maximum thickness determined in Clauses 5, 6 and 7 of this standard.

NOTE: The method for determining glass thickness is specified in Annex A.

4.2.2 Standard nominal thicknesses

The glass materials referred to in this standard are those with standard nominal thicknesses. The standard nominal thicknesses and thickness tolerances shall conform to the respective product standards.

4.2.3 Non-standard nominal thicknesses

Glass types with nominal thicknesses not specified in the standard and the requirements of this standard shall be applied using appropriate interpolation methods.

4.2.4 Glass area

For a given glass type and thickness, the glass area shall not exceed the minimum area determined in Clauses 5, 6 and 7 of this standard.

4.3 Requirements for glass framing

4.3.1 Glass frames

Frames shall withstand the appropriate design loads while limiting design load-induced deformations along the stress direction to:

– (1/150) of the span for residential sliding windows and doors (regardless of height) and for other buildings less than 10m high;

– (1/240) of the span for residential doors in buildings over 10m high.

**4.3.2 Glass installed directly in building structures **

Glass directly attached to building components using appropriate fastenings shall also meet the allowable deflection requirements specified in 4.3.1.

4.3.3 Mixed framing

Glass supported along the full length of the top and bottom horizontal edges by one type of frame and along the vertical direction by another type of frame, while still meeting the allowable deflection specified in 5.3.1.

4.4 Design requirements for special cases

4.4.1 General requirement

When using glass in special cases not covered by this standard, manufacturers shall be consulted regarding design data and maximum stresses not exceeding the values given in 4.4.2.

4.4.2 Design stresses

For annealed glass types, the design stresses are specified in Table 1.

For glass types other than annealed glass, the design stress is determined by multiplying the stress listed in Table 1 by the factor given in Table 2.

Table 1 – Design stresses for annealed glass

Table 2 – Wind load factors for glass of equal thickness

5. Wind load resistance requirements

5.1 General

This clause specifies the procedure for determining the minimum thickness for a given area or the maximum area for a given thickness, for different glass types in accordance with wind load resistance requirements.

5.2 Design wind pressure

For high-rise buildings, depending on the glass type, span, area, and thickness, the effects of wind pressure and static loads need to be considered as specified in TCVN 4088:1995 and TCVN 2737:1995.

5.3 Ordinary annealed glass with standard nominal thicknesses

5.3.1 General requirements

The standard nominal thickness of ordinary annealed glass for a given span or area, or the maximum area or span for a given standard nominal thickness, is determined according to Clauses 5.3.2 and 5.3.3. After glazing, the frame must ensure that the allowable stress deflection in the direction of the design wind load does not exceed:

– (1/150) of the span for residential sliding windows and doors (regardless of height) and for other buildings less than 10 m high;

– (1/240) of the span for residential doors in buildings over 10 m high.

5.3.2 Rectangular glass panels with framing on all edges

For rectangular glass panels with framing on all edges, the dimensions are obtained from Figure 2 with an aspect ratio equal to or less than the value given in the chart. For higher aspect ratios, Figure 3 applies, with the shorter side of the rectangle considered as the span.

5.3.3 Rectangular glass panels with framing on two opposite edges

For rectangular glass panels with framing on two opposite edges, the dimensions are obtained from Figure 3. For design wind pressures greater than 5 kPa, the equation given in Annex B and specified in Clause 5.4.2 applies.

Figure 2 – Dimensions chart for rectangular ordinary annealed glass panels of standard thickness with aspect ratio less than or equal to the given value and framing on all edges

Figure 3 – Span chart for rectangular float ordinary annealed glass panels of standard thickness with framing on only two opposite edges and for rectangular panels with high aspect ratio and framing on all edges

5.4 Ordinary annealed glass not in the standard nominal thickness group

5.4.1 Rectangular glass panels with framing on four edges

For rectangular glass panels with a given minimum thickness and framing on four edges, the product pA is a constant (K). The maximum area of a glass panel with a minimum thickness other than in Figure 2 is calculated by determining the K factor, through K1 from equation (B.1) or K2 from equation (B.2) in Annex B.

The maximum area value (A) for any design wind pressure value (p) is determined by the following equation:

A = K/p

where:

A is the area of the glass panel, in m²;

K is the glass thickness constant;

p is the design wind pressure, in kPa.

NOTE:

– The calculated line for the minimum thickness of a glass panel can be drawn in Figure 2 by drawing a line parallel to the line passing through the point p = 1, A = K for glass of standard nominal thickness (slope = -1).

– The maximum aspect ratio with the calculated line in Figure 2 can be calculated from equation (B.6) in Annex B for glass panels with minimum thickness less than or equal to 6 mm, or from equation (B.9) for glass with minimum thickness greater than 6 mm.

5.4.2 Rectangular glass panels with framing on only two opposite edges

For rectangular glass panels with a given minimum thickness and framing on only two opposite edges, the product pb2 is a constant C. The maximum span for a glass panel with a minimum thickness other than in Figure 3 is calculated by determining C from equation (B.3) in Annex B.

The maximum span size for any design wind pressure value is determined by the following equation:

b = (C/p)^1/2

where:

b is the maximum span size, in m;

p is the design wind pressure, in kPa.

NOTE: The calculated line for a minimum thickness of the glass panel can be drawn in Figure 3 by drawing a line parallel to the line corresponding to the standard nominal thickness (slope = -0.5), passing through the point p = 1, b = C^1/2.

5.5 Glass types other than ordinary annealed glass

5.5.1 General requirements

The required thickness for glass types other than ordinary annealed glass is calculated using the load factor (F) in Table 2 specified in 5.5.2 or 5.5.3.

Where safety considerations do not allow a reduction, a more appropriate load factor than in Table 2 may be used.

5.5.2 Standard nominal thicknesses

The maximum area or span for a given minimum thickness, or the minimum thickness for a given span or area, of any glass type in Table 2 is calculated by dividing the design wind pressure (p) by the load factor (F) given in Table 2 and using this adjusted pressure in the method specified in 5.3.

When the design wind pressure exceeds 5kPa, the appropriate equation in Annex B as specified in Clause 5.4.1 or 5.4.2 applies.

Annex C provides tables and charts corresponding to the glass types listed in Table 2. These charts and tables have been pre-calculated using the above method, so applying these charts and tables does not require reference to Figure 2 or Figure 3.

5.5.3 Non-standard thicknesses

The maximum span or area for a given minimum thickness, or the minimum thickness for a given span or area of any glass type according to Table 2 will be obtained by dividing the design wind pressure (p) by the load factor (F) given in Table 2 and using this adjusted pressure in the method specified in 5.4.

6. Human impact safety requirements

6.1 General

This clause specifies the requirements to ensure human safety in locations where human impact with glass frequently occurs.

NOTE:

1) Meeting the requirements of Clause 6 will reduce the risk of injury to people when impacting glass. However, this does not mean that the glass will not break under all impact conditions, but only that it will not break under the most common types of impact, or when broken, the occurrence of injuries due to sharp, small glass fragments will be limited due to the special protective properties of the glass, or the limited size of the glass, or the breakage characteristics of the glass.

2) Meeting these requirements necessitates that doors and glass panels be considered as framed or unframed according to 6.2.

3) When using transparent glass for doors or sidelights (on either side of a door) or when installing glass in locations that may be mistaken for an open door or unobstructed walkway, the glass must be marked or decorated in a way that clearly indicates the presence of the glass panel. However, such marking or decoration cannot substitute for the required use of safety glass in necessary locations specified in this clause.

6.2 Door and glazing frames

Doors or glass partitions are considered framed if their frame structures simultaneously satisfy:

a) provide support along the full length of the edges of the door or glass partition; and

b) limit deflection appropriately according to 4.3.

Doors and glass partitions (including door or partition frames) that do not comply with the requirements of this clause will be considered unframed.

6.3 Exposed edges

The edge of a glass panel without framing will be considered an exposed edge, unless that edge is continuously joined to another glass panel. Sharp corners of exposed edges shall be safety ground.

NOTE: An unframed glass panel may have no exposed edges or one or more exposed edges.

6.4 Substitution of safety glass

Ordinary annealed glass shall not be used to replace Group A or Group B safety glass materials where safety glass materials are required.

Group A safety glass conforming to Table 3 may be used to replace ordinary annealed glass in the same case where ordinary annealed glass is accepted.

Group B safety glass may be used to replace ordinary annealed glass in the same case where ordinary annealed glass is accepted, subject to the area, span and thickness limits applicable to ordinary annealed glass.

6.5 Use of safety glass with non-standard thicknesses

Safety glass with non-standard thicknesses may be used if the maximum area or span of the glass according to Tables 3 to 7 is adjusted in accordance with 4.2.3.

6.6 Insulating glass units

When using insulating glass units in the cases specified in this section, the maximum area specified in this section may be multiplied by 1.5, provided that each glass layer of the unit meets the relevant requirements.

6.7 Identification of safety glass materials

Each safety glass panel shall be clearly marked as specified.

When installing laminated safety glass, safety organically coated glass, or safety wired glass, each batch or installed glass panel shall be marked and accompanied by a manufacturer’s or supplier’s confirmation to affirm that the batch or glass panel was cut from a type of safety glass with clear markings, in accordance with current regulations.

If glass with non-standard thickness is used, the glass shall be marked according to this regulation, and the minimum thickness of the glass, in millimeters, shall be clearly marked on the glass.

6.8 Door glazing

Door glazing shall be Group A safety glass conforming to Table 3. Except in the following cases:

a) for framed glass doors on all four edges, ordinary annealed glass with a maximum area of 0.5 m² according to the criteria in Table 4 and with a protective bar more than 40 mm wide may be used;

b) for frameless doors, tempered safety glass with a minimum standard nominal thickness of 10 mm may be installed.

c) bathroom doors or shower enclosures are glazed according to 6.13.

NOTE: The requirements for door glazing are similar for residential and non-residential buildings.

6.9 Sidelights

6.9.1 Framed sidelights

Glass panels of framed sidelights with the nearest vertical sight line of the opening less than 300 mm from the nearest edge of the door opening shall be glazed with Group A safety glass according to Table 3. Except in the following special cases:

a) for non-residential buildings, ordinary annealed glass according to Table 4 may be used in the following cases:

– the clear opening width of the partition is not greater than 500 mm for each panel;

– the bottom edge of the partition is 500 mm or more above the finished floor level;

– when the clear height of the partitions is not greater than 1,000 mm for each partition;

b) for non-residential buildings, ordinary annealed glass conforming to Table 6 may be used if the clear opening width is greater than 2m and simultaneously:

– the frame columns of the partition are embedded at least 300 mm from the finished floor level; or

– ordinary annealed glass with a minimum standard nominal thickness of 10 mm is used;

c) for residential buildings, ordinary annealed glass conforming to Table 6 may be used provided the lowest sight line is 1,200 mm or more above the finished floor level.

If the lowest sight line is below 1,200 mm above the finished floor level, ordinary annealed glass according to Table 4 may be used for partition areas less than 0.5 m².

6.9.2 Unframed sidelights

– unframed sidelights without exposed edges shall be Group A safety glass meeting the requirements of Table 3 or Table 7;

– unframed sidelights with any exposed edge shall be glazed with Group A safety glass meeting the requirements of Table 3 or Table 7 unless the glass has a standard nominal thickness of 10 mm or more.

6.10 Partitions not identified as doors or sidelights that could be mistaken for unobstructed passageways

Partitions considered capable of being mistaken for an open door or unobstructed passageway shall meet the requirements of 6.10.1 and 6.10.2.

Partitions are considered incapable of being mistaken for an open door or unobstructed passageway in the following cases:

a) the clear width of each glass panel is up to 500 mm;

b) the lowest sight line of the opening (see Figure 1) is 500 mm or more above the finished floor level;

c) the partition is marked with symbols or decoration, acid etched on the glass, of sufficient size to be easily recognizable, or painted, patterned to indicate the presence of the partition;

d) the partition has protective chair rails or similar details;

e) there are forms of detailed expression on the partition;

g) the floor levels on both sides of the partition differ by more than 500 mm.

6.10.1 Framed partitions

Framed partitions shall be glazed with Group A safety glass according to Table 3, except for areas limited to 0.5 m², ordinary annealed glass meeting Table 4 may be used.

6.10.2 Unframed partitions

Unframed partitions shall be glazed with Group A safety glass according to Tables 3 and 7, with notes on size requirements for Group A safety glass types.

6.11 Partitions other than doors or sidelights, forming enclosures for rooms in residential buildings

6.11.1 Framed partitions

All framed partitions in residential buildings with the lowest sight line (see Figure 1) of the partition less than 500 mm from the finished floor level shall be Group A safety glass conforming to Table 3.

In the following cases, ordinary annealed glass may be used:

a) areas up to 0.1 m² with minimum nominal thickness of 3 mm;

b) areas up to 0.3 m² with minimum nominal thickness of 4 mm;

c) areas up to 2.0 m² with minimum nominal thickness of 5 mm.

6.11.2 Unframed partitions

All unframed partitions in residential buildings with the lowest sight line (see Figure 1) less than 500 mm above the finished floor level shall comply with the requirements of Tables 3 and 7.

6.12 Doors, screens and enclosures for baths

All glass panels used for doors, screens, standing bath enclosures and associated windows with the lowest sight line less than 1,500 mm above the finished floor level shall be Group A safety glass conforming to Table 3 or Group B safety glass conforming to Table 5.

When such screens or doors have an exposed edge, Group A tempered safety glass according to Table 3 with a minimum thickness of 5 mm shall be used.

6.13 Shopfronts and internal partitions

6.13.1 General requirement

This clause applies to all partitions other than doors or sidelights on glass walls at the front of lobbies and glass partitions in dwellings and other buildings. This does not apply to glass fins that could be subject to human impact if the width of those fins is greater than 500 mm.

Table 3 – Maximum area of Group A safety glass from clear or figured glass, used for framed doors, framed partitions and other framed glass partitions

Table 4 – Maximum area of ordinary annealed clear or figured glass for framed doors, framed edge glass partitions and other framed glass partitions

Table 5 – Maximum area of Group B safety glass, for bath doors, screens and enclosures

Table 6 – Maximum area for annealed glass of shopfronts, internal partitions and other glass partitions

Table 7 – Unframed shopfronts, internal partitions and other glass partitions

6.13.2 Framed partitions

Framed partitions other than doors or sidelights on internal partitions or glass walls at the front of lobbies shall be glazed with Group A safety glass according to Table 3.

If such partitions are incapable of being mistaken for an open door or unobstructed passageway, they may be glazed with ordinary annealed glass according to Table 6.

6.13.3 Unframed partitions

6.13.3.1 Partitions unframed at the top edge

Partitions framed on three edges except the top edge shall be glazed with Group A safety glass according to Table 3 or ordinary annealed glass according to Table 6, provided that the top edge of the partition is 1,500 mm or more above the finished floor level and does not create the illusion of an open door or unobstructed passageway.

6.13.3.2 Partitions unframed at two sides

Partitions framed at the top and bottom edges and with one or two exposed sides shall be glazed according to Table 7 if the lowest sight line of the glass is greater than 1,500 mm above the finished floor level and the height of the partition is not greater than 1,000 mm, in which case ordinary annealed glass with a nominal thickness of 6 mm or more may be used.

6.14 Sloped glazing

Sloped glazing designed with an inclination of not less than 30° from the horizontal, whether fixed or openable, shall be capable of withstanding appropriate loads and may have a safety mesh installed below the glass to prevent glass fragments from falling in case of glass breakage.

In addition, the glass shall also be designed to withstand any support loads that may occur on the slope in certain special cases, such as loads due to rain, snow, etc.

7. Requirements for glazed canopies and sloped glazing

7.1 Canopies

For windows with canopies, whether fixed or openable, the length of the canopy (glazing panel) made of annealed glass shall not exceed the values listed in Table 8 provided that the design wind pressure does not exceed 0.9 kPa.

For higher wind pressures and other glass types, the length of the canopy shall be determined according to the wind load requirements for rectangular glass panels supported only on two opposite edges, using the pressure factor for the wind load resistance specified in Clause 5. Where necessary, the human impact safety requirements specified in Clause 6 shall be considered.

Table 8 – Maximum length of canopies made of ordinary annealed glass

Unit: millimeter

7.2 Sloped glazing (including skylights)

7.2.1 General requirement

Sloped glazing shall be designed with an inclination of less than 70° from the horizontal.

In addition, the glass shall be designed to withstand any loads that may occur on the slope in certain special cases, such as snow loads, with reduced design stresses.

Glass used for slopes less than 30° from the horizontal shall be Group A safety glass. For slopes of 30° or more, either Group A or B safety glass may be used.

If the highest point of the glass is more than 5.0 m above the finished floor level, tempered safety glass shall not be used, except when the slope of the glass is 70° or more from the horizontal or when a safety mesh is used below the glass to prevent glass fragments from falling in case of glass breakage.

NOTE: Different laminated safety glass types have different breakage characteristics. When selecting safety glass, their breakage characteristics should be considered.

7.2.2 Design requirements

7.2.2.1 Design loads for trafficked roof coverings

For glazing flat or nearly flat roofs used as pedestrian walkways or for recreational areas, the appropriate load is 1.8 kN on an area of 150 mm diameter at the center of the glass panel or the following distributed dynamic load:

a) for residential buildings: 1.5 kPa

b) for public buildings: 3 kPa

whichever load may cause greater consequences.

7.2.2.2 Design loads for non-trafficked roof coverings

For flat or sloped glass roofs that only cover components and have no dynamic loads from traffic or crowds, the appropriate design loads are as follows:

a) for sloped roofs with an inclination below 30° from the horizontal, the equivalent load is 1.1 kN on an area of 150 mm diameter at the center of the glass panel;

b) for sloped roofs with an inclination greater than 30° and less than 70° from the horizontal, the vertical load is 0.5 kN on an area of 150 mm diameter at the center of the glass panel.

For unsupported glass panels with a width of 450 mm or less, support for concentrated loads is not required, even for sloped roofs.

NOTE: The stresses developed within the glass and the strength of the glass depend on the hardness, size and contact area of the applied load as well as its size and support conditions.

7.2.3 Glass spans for non-trafficked roof coverings

Table 9 gives the maximum allowable dimensions for the glass types and thicknesses corresponding to the loads specified in 7.2.2.2 for non-trafficked roof coverings, subject to the following limits:

a) maximum design wind pressure: 1.2 kPa;

b) for glass panels supported on two opposite edges, the width of the glass panel is not less than the span;

c) for glass panels supported on four edges: maximum length of 3.66 m for laminated glass and 4.0 m for tempered glass;

d) snow loads are not applied;

e) the following design stresses were used to determine the allowable spans specified in Table 9:

1) laminated glass: 15.2 MPa

2) tempered glass: 43.0 MPa

3) heat-strengthened laminated glass: 24.0 MPa

Table 9 – Maximum allowable spans for sloped glazing of non-trafficked roof coverings

8. Installation requirements

8.1 Overview

This clause specifies the basic requirements for glass installation. The installation of insulated multiple-layer glass units not covered in this section. For the installation of such glass, refer to the manufacturer’s instructions. Instructions from different manufacturers may vary.

8.2 Dimensional requirements

8.2.1 General requirements

The dimensions of the rebate depth, edge cover, front and back clearances of the glass panel in Figure 1 shall not be less than the values listed in Table 10 for different glass thicknesses.

Table 10 – Minimum glass dimensions for different glazing materials (clear glass, tinted glass, reflective glass)

Unit: millimeter

8.2.2 Front putty thickness

The thickness of the front putty shall not be less than 10 mm for glass panels with an area up to 1 m² and not less than 12 mm for glass panels with an area from 1 m² to 2 m².

8.2.3 Dimensions of glazing grooves and rebates

The dimensions of the glazing grooves and rebates shall comply with the requirements of 8.2.1 and 8.2.2 and shall meet the dimensional requirements for the glass panels regarding the glazing frame.

8.3 Use of glass materials

8.3.1 Material suitability: Only use glass materials that meet the following requirements:

– Glass type suitable for the intended use as recommended by the manufacturer;

– Only use glass materials in places suitable for the adjacent materials, including frames and glass types, to ensure material compatibility;

– Only use glass materials when the expected service life can be determined.

8.3.2 Setting and location blocks: The number and location of setting and location blocks as guided in Figures 4 and 5, necessary to maintain the required clearances. Each block shall cover the glass thickness.

For fixed windows, setting blocks positioned at points about 1/4 of the edge are appropriate. For movable window frames, setting and location blocks may be positioned as follows:

a) not less than 30 mm from the corner; or

b) at positions not coinciding with rigid anchor points of the door, if those points are within 30 mm from the corner and 1/4 points.

The length of each setting block shall not be less than 12 mm and not greater than 30 mm per 1 m² of glass panel area.

The length of each location block shall not be less than 25 mm.

8.3.3 Spacer pads: Spacer pads, as shown in Figure 6, are used when deemed necessary to create front and back clearances of the glazing frame, keeping the glass within the glazing groove.

Spacer pads are used on both opposite sides of the glass surface, except for the backing putty on the glass-holding surfaces and rebates.

The pads can be evenly distributed, spaced no less than 300 mm apart. The pads shall coincide with the anchor plates fixed by bolts or rivets. In case the anchor plates are snugly fitted in the groove, a continuous cover pad is placed about 50 mm from each corner. Pads shall not be placed coinciding with the position of rigid or locating blocks.

The pads shall have a length of about 25 mm and a height appropriate to the depth of the rebate and the glazing method, so that they can be covered by the glass compounds by not less than 3 mm. The cover pads shall have a thickness equal to the front and back clearances to position the glass within the frame.

8.3.4 Anchor plates: Anchor plates shall be capable of clamping the glass securely under any load condition.

Wooden anchor plates may be tightly wedged by bolts or dowels – bolts must be used if installing large or heavy glass panels.

Metal or plastic anchor plates shall also be locked in place by bolts or screws, or snugly fitted into the channel.

8.4 Preparation of glazing grooves, channels and anchors: Glazing grooves, channels and anchor plates shall be cleaned and cleared of all oils, moisture and other compounds. The rebates shall be primed or coated with sealant as recommended by the glass material manufacturer.

Figure 4 – Position of setting blocks

Figure 5 – Position of location blocks

Figure 6 – Position of spacer pads

9. Installation of unframed tempered glass

9.1 Overview

This section applies to the installation of unframed tempered glass.

NOTE:

1) The installation of unframed tempered glass (in the form of glass wall panels, mostly fixed except for some that can serve as doors) provides a method of glazing large spaces without the use of transoms or frames. Such structures can be supported entirely or partially from the building structure depending on the size of the glazed opening. They require completely different installation techniques than framed glass structures.

2) For fully suspended glass structures, each glass panel is suspended together with adjacent glass panels and joined at the corners of the glass panel by connecting devices through specially designed holes or grooves in the glass. Each row of glass (except the top row) is suspended from the row above, and the entire structure, except the doors, is suspended and rigidly connected to a building component that can support the entire static load of the glass structure plus any forces due to wind loads.

3) The main limiting factor on the height of the suspended structure is the tensile strength of the holes in the glass panels in the top row. Normally, the two holes in the glass share the load equally, although some oversized holes may be created to help prevent slippage.

4) In some special cases, the glass may be stacked or supported in other ways.

9.2 Design considerations

9.2.1 Fall safety requirement

The design of tempered glass structures must ensure that when any part of the structure breaks, it does not lead to the collapse of the remaining parts.

9.2.2 Structure

The exterior face must be made of tempered glass and where necessary must be supported against wind loads by fins or stiffeners at least 12 mm thick engaged at the edge of the glass panel adjacent to the partition and usually arranged vertically. The fins must be connected to the partition by coupling devices and must be attached to the building structure so that it can support the partition to withstand wind loads.

9.2.3 Glass design stresses

The façade glass panels, stiffening fins, and attachments to the building structure must be designed to withstand appropriate wind loads according to standard TCVN 2737:1995. The maximum design stress for tempered glass fins under wind load must be 43 MPa and for the façade it is 50 MPa. To resist bending forces, the width of the fin must not exceed 18 times the thickness of the glass.

9.2.4 Preventing expansion and movement of the structure

9.2.4.1 Suspended structures: The downward thermal expansion of a fully suspended partition must be prevented by creating a gap in the floor or at the door threshold for the bottom edge of the partition. Rigid blocks are not used at this edge but spacing pads are still used to keep the glass centered in the glazing gap. Soft gaskets, plastic or neoprene rubber must be used. The gap must be deep enough to create a space equal to 1-1.5 times the thickness of the glass plus a clearance of not less than 2 mm between the lowest edge of the partition and the bottom of the rebate (see Figure 7). The rebate must be cleared of obstructions and must be rigid enough to withstand wind loads on the partition (see Clause 5 for wind loads).

The rebates at each end of the partition or appropriate preparations such as flexible connections must be designed to allow lateral thermal expansion of the partition. The necessary edge engagement or edge clearance must be determined for each specific glass structure.

The coupling devices connecting the fins to the partitions must have sliding slots to allow for movement due to thermal expansion or other structural movements of the fins and partitions when necessary while still resisting wind loads.

NOTE: Sliding slots may not be required for glass structures where the vertical fins are fixed to the head of the opening and the partitions are similarly fixed or suspended from the head of the opening, as the expansion and movement of the fins and partitions will then be in the same direction.

Figure 7 – Glass framing structure for suspended tempered glass installation

9.2.4.2 Doors directly supported from the floor and partially suspended structures

The upward thermal expansion of doors directly supported on the floor must be considered. It is permissible to design a gap larger than 3 mm between the top of the door and the bottom of the transom for partition structures up to 5 m high and to add a gap of less than 1 mm for each 3 m of height or portions of the glass structure over 5 m. Similar thermal expansion should be considered for partially suspended structures when the bottom row of partitions is supported directly from the floor similar to doors.

9.2.5 Adjustment: The partition suspension beams will provide vertical adjustment to compensate for minor defects in the opening, and … deflection of the upper beam due to the weight of the glass.

9.3 Glazing techniques

9.3.1 General requirements: Tempered glass shall not be cut or further processed after tempering. Any cutting, drilling, grooving, or notching must be accurately carried out before tempering.

The assembly of tempered glass must be performed by skilled workers. The edges and surfaces of tempered glass must not be chipped during installation.

The manufacturer’s installation instructions must be strictly followed.

9.3.2 Sizing: The dimensions of the glass should be determined based on the dimensions of the opening before ordering.

NOTE: The dimensions and squareness of the opening for tempered glass installation must be accurately measured on site before beginning glass production.

9.3.3 Installation

9.3.3.1 Suspended structures

The glazing will start from the top fins, dropped vertically and fixing the bottom edges on the horizontal plane.

The middle panel in the top row will be fitted next, followed by the side panels of the top row.

After completing the installation of the top row, the subsequent rows will be installed similarly, starting from the middle panel.

The steel consoles used to connect the glass fins to the building will be bolted to the glass fins and all bolts must be tightened according to the manufacturer’s instructions.

At the fixed bolt points, great care is needed during installation, using fiber or rubber pads to ensure there is no contact between glass and glass or glass and metal. All glass panels and fins must be fixed to each other with spacing, leaving a gap of about 3 mm. That gap can accommodate varying weather conditions as desired by being H-shaped extruded from rubber or plastic or silicone sealant can be injected into the gap to create a bond.

9.3.3.2 Sill installation: Place synthetic rubber or suitable material location blocks at the position where the glass panel is supported by the sill (Figure 8).

Figure 8 – Glass framing structure for supported tempered glass installation

Annex A (normative) Determination of maximum and minimum thickness

A.1 Scope

This annex describes the method for determining the maximum and minimum thickness of a glass panel.

A.2 Equipment, tools

A.2.1 Dial gauge with graduation to 0.01 mm, dial diameter 55 mm.

A.2.2 Micrometer, 60 degree graduation type, including 0.3 mm diameter corner pin, or equivalent measuring device.

A.3 Procedure

1) Using the dial gauge, measure at 4 midpoints of the edges of the glass panel. The measured maximum thickness is the largest dimension of the glass panel.

2) Using the micrometer, measure at 4 midpoints of the edges of the glass panel. The measured minimum thickness is the smallest dimension of the glass panel.

NOTE: The thickness measurement points for figured glass panels at the highest points with figuring are the maximum thickness. At the bottom points are the minimum thickness.

Annex B (normative) Basis for determining the thickness or area of glass panels in accordance with wind load requirements

B.1 Rectangular glass panels with framing on all edges

Figure 2 is based on tests with a safety factor of 2.5 times the destructive load.

The test results for plotting the graph are calculated using the following equations:

– for glass up to 6 mm thick: pA = K₁ = 0,2t^1,8                         …(B.1)

– for glass thicker than 6 mm: pA = K₂ = 0,2t^1,6  + 1,9                …(B.2)

where:

p is the design wind pressure, in kPa;

A is the area of the glass panel, in m²;

K₁: K₂ are constants of the glass panel thickness;

t is the minimum thickness of the glass panel, in mm.

B.2 Rectangular glass panels with framing on two opposite edges

Figure 3 is based on the calculation equation for a uniformly supported beam with a uniformly distributed load. Thus, the maximum span size of the glass panel for any thickness or design wind pressure is calculated by the equation:

b²p = C = t².ƒ/750                                                                                  …(B.3)

where:

b is the span, in m;

p is the design wind pressure, in kPa;

C is the glass panel thickness constant;

t is the minimum thickness of the glass panel, in mm;

ƒ is the design stress of the glass, in MPa.

In Figure 3, the design stress of glass up to 6 mm thick is 16.7 MPa and the design stress of glass thicker than 6 mm is 15.2 MPa.

B.3 Maximum aspect ratio applicable to Figure 2 for rectangular glass panels with framing on two opposite edges

For each minimum thickness of a rectangular glass panel with an aspect ratio (a/b) given in Figure 2, it will be more reasonable with the value given in Figure 3 for glass panels with framing on two opposite edges. The value of the aspect ratio a/b at the same area (A) is determined as follows:

a) For glass less than 6 mm thick:

(i) For 4-edge framing, equation (B.1) can be presented as follows:

abp = 0,2t^1,8                                                                  … (B.4)

(ii) For 2-edge framing, equation (B.3) can be presented as follows:

b²p = 16,7 t²/750                                                            … (B.5)

Dividing equation (B.4) by equation (B.5), we have:

a/b = 8,98/t^0,2                                                                 … (B.6)

The above formula gives the maximum aspect ratio applicable to Figure 2 for glass less than 6 mm thick.

b) For glass thicker than 6 mm:

(i) For 4-edge framing, equation (B.2) can be presented as follows:

abp = 0,2t^1,6 + 1,9                                                          … (B.7)

(ii) For 2-edge framing, equation (B.3) can be written as follows:

b²p = 15,2t² / 750                                                           … (B.8)

Dividing equation (B.7) by equation (B.8), we have:

a/b = 49,34 (0,2t^1,6 + 1,9)/t²                                             … (B.9)

The above formula gives the maximum aspect ratio applicable to Figure 2 for glass thicker than 6 mm.

It should also be noted that the value of the aspect ratio a/b given in equations (B.6) and (B.9) is independent of the value of p.

Annex C (normative) Charts for determining the maximum allowable area and span of glass types

DESIGN WIND PRESSURE (p), kPa

Figure C.1 – Dimensions of rectangular ordinary annealed glass panels of standard thickness with aspect ratio less than or equal to the given value and with framing on all edges

DESIGN WIND PRESSURE (p), kPa

Figure C.2 – Span of rectangular ordinary annealed (float) glass panels of standard thickness with framing on only two opposite edges and for rectangular panels with high aspect ratio with framing on all edges

DESIGN WIND PRESSURE (p), kPa

Figure C.3 – Dimensions of rectangular tempered (from float) glass panels of standard thickness with framing on the edges and aspect ratio less than or equal to the given value

DESIGN WIND PRESSURE (p), kPa

Figure C.4 – Span for rectangular tempered (from float) glass panels of standard nominal thickness with framing on only two opposite edges and for rectangular panels with high aspect ratio with framing on all edges

DESIGN WIND PRESSURE (p), kPa

Figure C.5 – Dimensions of rectangular heat-strengthened (from float) glass panels of standard thickness with framing on all edges and aspect ratio less than or equal to the given value

DESIGN WIND PRESSURE (p), kPa

Figure C.6 – Span for rectangular heat-strengthened (from float) glass panels of standard nominal thickness with framing on only two opposite edges and for rectangular panels with high aspect ratio with framing on all edges

DESIGN WIND PRESSURE (p), kPa

Figure C.7 – Dimensions of rectangular ordinary annealed (from float) glass panels of standard nominal thickness used in insulating (double) glazing with framing on the edges

DESIGN WIND PRESSURE (p), kPa

Figure C.8 – Dimensions of rectangular laminated (from ordinary annealed float) glass panels of standard nominal thickness with framing on all edges and aspect ratio less than or equal to the given value

DESIGN WIND PRESSURE (p), kPa

Figure C.9 – Span for rectangular laminated (from ordinary annealed float) glass panels of standard nominal thickness with framing on two opposite edges and for rectangular panels with high aspect ratio with framing on all edges

DESIGN WIND PRESSURE (p), kPa

Figure C.10 – Dimensions of rectangular ordinary annealed figured glass panels of standard nominal thickness with framing on all edges and aspect ratio less than or equal to the given value

DESIGN WIND PRESSURE (p), kPa

Figure C.11 – Dimensions of rectangular ordinary annealed rolled glass panels of standard nominal thickness with framing on two opposite edges and for rectangular panels with high aspect ratio with framing on all edges

DESIGN WIND PRESSURE (p), kPa

Figure C.12 – Dimensions of rectangular heat-tempered rolled glass panels of standard nominal thickness with framing on all edges and aspect ratio less than or equal to the given value

DESIGN WIND PRESSURE (p), kPa

Figure C.13 – Span of rectangular heat-tempered rolled glass panels of standard nominal thickness with framing on two opposite edges and for rectangular panels with high aspect ratio with framing on all edges

DESIGN WIND PRESSURE (p), kPa

Figure C.14 – Dimensions of rectangular wired glass panels of standard nominal thickness with framing on all edges and aspect ratio less than or equal to the given value

DESIGN WIND PRESSURE (p), kPa

Figure C.15 – Span of rectangular wired glass panels of standard nominal thickness with framing on two opposite edges and for rectangular panels with high aspect ratio with framing on all edges

Annex D (Normative) Tables for determining the maximum allowable area and span of glass types

Table D.1 – Maximum area for ordinary annealed float glass with framing on all edges

Table D.2 – Maximum span of ordinary annealed float glass with framing on two opposite edges

Table D.3 – Maximum area for tempered glass with framing on all edges

Table D.4 – Maximum span for tempered glass with framing on two opposite edges

Table D.5 – Area for heat-strengthened float glass with framing on all edges

Table D.6 – Maximum span for heat-strengthened float glass with framing on two opposite edges

Table D.7 – Maximum area for double glazing from float glass with framing on all edges

Table D.8 – Maximum area for laminated glass (ordinary annealed float) with framing on all edges

Table D.9 – Maximum span for laminated glass (ordinary annealed float) with framing on two opposite edges

Table D.10 – Maximum area for figured glass with framing on all edges

Table D.11 – Maximum span for figured glass with framing on two opposite edges

Table D.12 – Maximum area for heat-tempered figured glass with framing on all edges

Table D.13 – Maximum span for heat-tempered figured glass with framing on two opposite edges

Table D.14 – Maximum area for 6 mm wired glass with framing on all edges

Table D.15 – Maximum span for 6 mm wired glass with framing on two opposite edges