Section 2410 [DSA-SS, DSA-SS/CC, OSHPD 1 & 4] Structural Sealant Glazing (SSG)
The requirements of this section address the use of structural sealant glazing (SSG). These requirements shall not be used for butt joint glazing, point supported glass, and glass fins.
Design of structural sealant glazing (SSG) shall satisfy the following requirements:
- SSG shall be weather tight and serviceable, as defined in AAMA 501.4, under design story drifts associated with the design earthquake and no glass fallout shall occur at the drifts determined by ASCE 7, Section 13.5.9.
- The sealant utilized in the insulated glass units used in SSG shall be designed in accordance with ASTM C1249. The insulated glass unit design shall be in accordance with ASTM C1249, Section 6.7.2.
- Allowable stress for SSG shall not exceed 20 psi and shall have a minimum factor of safety of 5 as required by ASTM C1401.
- Design methodology shall address seismic movement in accordance with ASTM C1401, Section 30.3.4.
- SSG systems shall be supported for self-weight and lateral loading at each floor level of the building.
- Unitized SSG framing shall be anchored to the building floor bearing plate by screws or bolts and shall not rely upon gravity or frictional forces for attachment.
- Framing shall satisfy the out-of-plane deflection requirements of this code.
Testing and inspection of structural sealant glazing (SSG) shall satisfy the following requirements:
- The seismic drift capability of structural sealant glazing shall be determined by tests in accordance with AAMA 501.6, AAMA 501.4 and ASCE 7, Section 22.214.171.124.
- The applicability of the specific AAMA 501.6 and AAMA 501.4 testing shall be subject to approval by the building official.
- The panel test specimens used in the AAMA 501.6 and AAMA 501.4 testing shall include all glass types (annealed, heat strengthened, laminated, tempered) and insulated glass units that comprise more than 5 percent of the total glass curtain wall area used in the building.
- AAMA 501.4 test specimen shall include the same materials, sections, connections, and attachment details to the test apparatus as used in the building.
- Serviceability tests of SSG test specimen shall be performed in accordance with AAMA 501.4 after seismic displacement tests to the design story drift.
- The window wall system using structural sealant by different manufacturer/product category shall be qualified in accordance with AAMA 501.6 and AAMA 501.4 testing for the seismic drift required. Analysis as an alternative to testing is not acceptable for the purposes of satisfying the seismic drift requirements of the SSG system.
- Where unitized SSG is used with horizontal stack joints at each floor level and split vertical mullions that can move independently, only a story height single unit need to be tested under AAMA 501.6. Where continuous horizontal bands of SSG are used in the building, either two or four sided, the aspect ratio (height-to-length) of the test specimen shall be less than 1.0, contain not less than two interior vertical joints and all joints (vertical in the case of two sided), including the perimeter of the glass, shall be glazed with SSG.
- Where SSG continues around corners, the AAMA 501.4 test specimen shall include one corner panel to verify the kinematics of the corner condition under seismic drift.
- Quality assurance and inspection requirements shall include formalized post-installation tests using the point load testing procedure in accordance with ASTM C1392. The point load tests shall be done after the initial installation.
- Where the SSG is field assembled, hand pull tab tests in accordance with ASTM C1401, Section X2.1, one test every 100 linear feet, but not less than one test for each building elevation view shall be required.
Existing AAMA 501.4 and 501.6 test results satisfying the requirements of this section shall be permitted, in lieu of project specific tests, when approved by the building official.
Short- and long-term periodic performance monitoring shall be provided in accordance with ASTM C1401, C1392 and C1394. Inspection frequencies recommended in ASTM C1392 Section 5.1 shall be followed.
Complete design of the SSG system for gravity, wind and seismic forces shall be subject to review by the enforcement agency. Construction documents shall show structural details of glass and curtain wall system including:
- A design narrative explaining how the SSG is supported by the building and the mechanism used to accommodate seismic racking.
- Type of SSG and whether field or shop built.
- The means of supporting the glass during structural sealant curing time shall be shown in the construction documents.
- Typical curtain wall panel elevation, plan view and sections.
- Details of building corner joint to verify how the corner vertical mullion will move to accommodate the seismic drift.
- Joints between panel and floors at top and bottom.
- Joint between panels — including vertical and horizontal stack joints at intermediate and edge mullion.
- Member sizes for curtain wall panels.
- Glass pane sizes, thickness and type of glass.
- Contact width and thickness of structural sealant and sealant materials for shop and field installation/reglazing.
- Glass to aluminum joints (including primers, if any).
- Maximum roof/floor dead and live load deflection of the roof/floor framing members supporting the exterior curtain wall system.
- Required seismic separation or gap distance between the structural sealant glazing curtain wall and other adjacent cladding units.
- Mitigation of galvanic reactions between the roof/floor slab anchors, steel screw connections of aluminum sections and the aluminum anchorage components, if any.