Due to deformability of the polymeric interlayer, stiffness and strength of laminated glass are usually less than those corresponding to a monolith with same total thickness. A practical design tool consists in the definition of the "effective thickness", i.e., the thickness of an equivalent monolithic glass that would correspond to the same deflection and peak stress of the laminated glass, under the same constraint and load conditions. Very recently, a new model has been proposed for the evaluation of the effective thickness. Here, a comparison is made with the classical approach by Wölfel-Bennison and the new method is specialized to the most common cases of the design practice, providing synthetic tables for ease of reference and immediate applicability.

SUMMARYThe envelope of a building is mainly responsible for its energy demand. Different kinds of Double Skin Facades (DSF) are nowadays used as a building envelope to reduce the energy demand and improve aesthetical view of buildings. Although DSF are already extensively used, their thermal performance is not well understood. This study presents a decoupling method capable to evaluate thermal performances and analyze fluid phenomena in a DSF. The solar radiation effects were evaluated with an analytical model and Computational Fluid Dynamics (CFD) simulations were used to evaluate complex flow and thermal effect on a commercial DSF. With the decoupling approach to account for the effects of solar radiation and flow, the numerical results obtained by the CFD approach agree well with the experimental data collected on a full scale test room with a ventilated DSF. The method can be used to establish a database to develop a tool for DSF design.

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The structural design of glass curtain walls and facades is a challenging issue, considering that building envelopes can be subjected extreme design loads. Among others, the soft body impact (SBI) test protocol represents a key design step to protect the occupants. While in Europe the standardized protocol based on the pneumatic twin-tire (TT) impactor can be nowadays supported by Finite Element (FE) numerical simulations, cost-time consuming experimental procedures with the spheroconical bag (SB) impactor are still required for facade producers and manufacturers by several technical committees, for the impact assessment of novel systems. At the same time, validated numerical calibrations for SB are still missing in support of designers and manufacturers. In this paper, an enhanced numerical approach is proposed for curtain walls under SB, based on a coupled methodology inclusive of a computationally efficient two Degree of Freedom (2-DOF) and a more geometrically accurate Finite Element (FE) model. As shown, the SB impactor is characterized by stiffness and dissipation properties that hardly match with ideal rigid elastic assumptions, nor with the TT features. Based on a reliable set of experimental investigations and records, the proposed methodology acts on the time history of the imposed load, which is implicitly calibrated to account for the SB impactor features, once the facade features (flexibility and damping parameters) are known. The resulting calibration of the 2-DOF modelling parameters for the derivation of time histories of impact force is achieved with the support of experimental measurements and FE model of the examined facade. The potential and accuracy of the method is emphasized by the collected experimental and numerical comparisons. Successively, the same numerical approach is used to derive a series of iso-damage curves that could support practical design calculations.

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