Full-Scale Unit Modeling
The glass has been modeled using 0.5-in.- (12.7-mm-) square shell elements. The structural effect of the PIB layer is negligible and was not considered in the model. The silicone has been modeled using 0.5 x 0.25-in.2- (12.7 x 6.35-mm2-) rectangular shell elements. Because of the one- and two-dimensional nature of the beam and shell elements, rigid links were used to hold the actual threedimensional locations of the elements in space. Rigid links are linear elements that connect two nodes rigidly in space. The silicone was modeled as nonlinear material with shell elements configured perpendicular to the surface of the glass. The stress-strain curve of the material has been obtained from physical tests at room temperature (22°C) and is presented in Fig. 2 . The corner portion of the finite-element (FE) model is presented in Fig. 13.
The aluminum framing members are typical of a four-sided, structurally glazed, unitized curtain-wall system. Each framing member profile was unique and the properties of the sections have been calculated and are presented in Fig.
1. The volume of the air cavity has been maintained with fluid elements with bulk stiffness of 100 kPa. The four corners of the frame have been modeled with pinned anchors where one corner had non-zero out-of-plane restraint. The end of the horizontal beam elements were moment released at the shared node of the vertical beams to represent a pinned connection between the horizontal and vertical framing members.
There are certain elements of the physical specimen that have not been modeled numerically. These parameters include negligible effects, such as the stiffness of PIB, the effect of gravity, and local distortions of framing profiles. Other parameters that were not modeled and may have significant effects include the flexibility/plasticity of the frame corner connections and thin-walled beam behavior of the frame members. The torsional behavior of the thin-walled frame members differs from the as-modeled solid members. The influence of warping of the thin-walled section changes the torsional shape of deformation of the frame members and may have significant impact on the overall results. A difference in torsional deformation to the one observed in the physical test has been obtained in the numerical model.