Long term response of glass–PVB double-lap joints

The paper presents the results of an experimental research on the viscoelastic behavior of laminated glasses with polyvinyl-butyral interlayers. The problem is investigated with double lap joints under compressive loadings over a temperature range between -20 °C and 50 °C. The viscoelastic mechanical parameters of polyvinyl-butyral play a fundamental role in determining the response of laminated glass and consequently, their knowledge is required for a reliable design, especially in structural application, such as beams, plates, fins, columns, walls, façade and roofs. Tests were performed on specimens made of three glass plies under long-term loads in different conditions of temperature and relative humidity. Shear stresses and relative displacements among the glass-interlayer interfaces were measured. The response is presented and discussed. To obtain a long term creep model using time-temperature superposition, an eight terms Prony series and the shift factors obtained from the Williams, Landel and Ferry equation were considered.