Curtain-Wall Frame

The curtain-wall panel frame was pin-anchored in three corners by steel angles to restrain in-plane and out-of-plane displacement and allow for the rotation at the corners. The fourth corner was pulled out of plane using a hook-and-slide mechanism that is typical to a curtain-wall anchoring system. The anchoring and pulling mechanism was designed to allow for a full 12 in. (300 mm) of deflection in one direction.

The framing profiles used were designed for a previous flat-glazed project and no prior considerations for cold-bending the frame were developed into the frame design. The framing members were open-channel vertical shapes and closed tubular horizontal shapes. The horizontal members were attached to the vertical members with three to four fasteners, which were attached through clear holes in the vertical framing members and threaded into screw races in the hori­zontal member. See Fig. 1 for framing member profiles and section properties.

The IGUs were structurally glazed in shop into the frame using structural silicone sealant with a bite of 0.75 in. (19 mm) and a depth of 0.25 in. (6.4 mm), so that the 20-psi (138-kPa) industry-standard structural silicone design strength would be maintained at the 100 lbf/ft2 (4788 Pa) wind load.

Glass Make-up

The IGUs for the full-scale test were fabricated using two 0.25 in. (6.4 mm) pieces of fully tempered clear glass. A 13.2-mm mill-finish aluminum spacer

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established a 0.520-in. (13.2-mm) air space. On both sides of the spacer, an aver­age of 0.015 in. (0.4 mm) of pressed PIB provided a primary seal between the spacer and the glass. The IGU was glazed with 3/8 in. (9.5 mm) of structural sili­cone insulating-glass sealant.

Silicone

The structural silicone that was used as the secondary seal for this study was also the silicone used to attach the IGU to the aluminum frame. This two-part structural silicone conforms to both ASTM C1184 [11] and ASTM C1369 [12]. This particular silicone is described as Sealant “D" previously by Wolf and Cleland-Host [13], as shown in Fig. 2. Data gathered on the tensile strength of the IGU edge-seal assembly per the ASTM C1265 [14] configuration is presented in Table 1. This data includes ultimate tensile strength, as well as stress data at

2.5 %, 5 %, and 10 % strain.