CSA-S852-18 Blast-resistant window anchor systems.
4 Performance criteria 4.1 Performance objectives The performance objectives of blast-resistant window anchor systems shall be in compliance with Clauses 4.3.4 and 4.3.5 of CSA S850. 4.2 Performance requirements 4.2.1 184.108.40.206 The blast design of window retention anchors on new or retrofitted blast-resistant substrates shall conform to the principles of balanced design specified in Clause 11.2.3 of CSA S850 and the requirements of Clauses 220.127.116.11 and 18.104.22.168. 22.214.171.124 The supporting substrates of window systems shall have higher capacity than the window system and its connections to the substrate. 126.96.36.199 The strength of window retention anchors connecting the window system to the supporting substrates shall have higher structural capacity than the strength of the window system by a minimum factor of safety of 1.5. 188.8.131.52 The margin of safety required in Clause 184.108.40.206 can be provided by using factored design forces as described in Clause 6.2.2. 4.2.2 Windows on unretrofitted substrates, potentially having higher blast resistance than the attached substrate, or windows that have overstrengths necessitated by other functional requirements (e.g., ballistic windows) shall have performance objectives established by the building owner or by the authority having jurisdiction over the building, provided that the safety of the occupants is ensured. 4.2.3 The window retention anchors shall have sufficient strength to maintain their integrity during elastic window response prior to glass breakage, as well as inelastic response beyond the glass breakage, including the effects of the membrane action.
5.2 Loads 5.2.1 Blast loads for window anchor analysis shall not be less than the P-I combination that represents the capacity of the glazed window system meeting the performance criteria of Clauses 4.2.1 and 4.2.2. 5.2.2 For members subjected to non-uniform blast loads, the effect of non-uniformity on response shall be considered. 5.2.3 Unless it can be demonstrated to be unconservative, the effects of applicable loads acting concurrently with the blast load shall be considered in analysis. 5.3 Analytical modelling 5.3.1 The analytical model for window analysis shall include all components of the window system, unless eliminating the component from the model does not produce unconservative values for anchor design forces. 5.3.2 The analytical model for a window system shall reflect the equivalent mass, stiffness, and damping of the actual window system being analyzed. 5.3.3 The analytical model of a window system shall include the consideration of all possible failure modes under different types of stresses and their interactions, including the effects of elastic window response, window cracking and the membrane action of glazed windows.
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