ISO 1288-4:2016

Overview

ISO 1288-4:2016 - Glass in building - Determination of the bending strength of glass - Part 4: Testing of channel shaped glass specifies a laboratory method to determine the profile bending strength of wired or unwired channel shaped glass used in buildings. The standard defines specimen preparation, test apparatus, environmental conditioning and the evaluation principles. Limitations and fundamental concepts are described in ISO 1288‑1.

Key topics and technical requirements

• Scope: Applies to wired or unwired channel shaped glass; limits referenced in ISO 1288‑1.
• Specimens: Standard specimen length is 2 100 mm ± 5 mm. Dimensions (web width, flange height, flange/web thickness) must comply with product tolerances. Specimens stored in the test environment for ≥ 4 hours before testing.
• Apparatus:
  • Bending machine with stepless, shock‑minimizing loading and load accuracy of ±2.0%.
  • Supporting and bending rollers 50 mm diameter, length ≥ 550 mm, free to rotate.
  • Air bags and spreader plates to apply load: air bag pressurization 70 kPa for nominal widths ≤ 300 mm, 50 kPa for > 300 mm; air bag dimensions and spreader plate sizes are specified.
  • Rubber strips (6 mm thick, hardness 40 ± 10 IRHD) between specimen and supporting rollers.
• Test conditions: Temperature (23 ± 5) °C, relative humidity 40–70%, with temperature constant to ±1 °C during testing.
• Loading rate: Specimen bent with a uniformly increasing bending stress at (2 ± 0.4) MPa/s until failure; record maximum force and time to failure.
• Measurement accuracy: Web width to nearest 1 mm, flange height to 0.5 mm, thicknesses to 0.1 mm.
• Evaluation: Profile bending strength is calculated from the maximum measured force plus specimen self‑weight, the test span and the applicable section modulus (different values when flange or web is in tension). Values for common profiles are provided in an informative annex.
• Reporting: Detailed per‑specimen data required (geometry, measured values, section modulus, whether flange or web in tension, profile strength in MPa, time to breakage). No averaging of individual results.

Applications and users

This standard is essential for:

• Glass manufacturers and product developers validating strength of channel shaped glass (wired or unwired).
• Accredited testing laboratories performing routine type testing and quality control.
• Structural engineers, façade designers and architects specifying channel glass in building envelopes, skylights or internal partitions.
• Certification bodies and regulators assessing compliance with building material performance requirements.

ISO 1288-4 helps ensure consistent, repeatable determination of bending performance so designers and specifiers can assess suitability and safety of channel shaped glass products.

Related standards

• ISO 1288-1 (Fundamentals of testing glass)
• Other parts of ISO 1288 (Parts 2, 3, 5 - alternative bending/ring tests)
• ISO 48 (Rubber hardness measurement referenced for pads)
• ISO 16293-1 (Basic soda lime silicate glass product properties)

Keywords: ISO 1288-4:2016, channel shaped glass, bending strength, profile bending strength, glass testing, glass in building, specimen testing.