Abstract
This paper deals with initial geometrical imperfections of the structural glass members made of flat glass. The design of the load bearing glass structures is relatively common in modern architecture, but there is not an Eurocode on design of glass members. Thus, practical design is still a challenge for structural engineers. In the case of structural glass members with problems of lack of stability (columns, beams and beam-columns), it is necessary to know the shape and size of the initial geometrical imperfections to carry out a static design. European product standards of float glass panes distinguish several types of geometrical imperfections. In the frame of this paper, the measurement and evaluation of the most important of them – overall bend – is presented. The initial geometrical imperfections (in the shape of overall bend) were measured on the 33 specimens. But in the real structures we can recognize three types of imperfections: geometrical imperfections of a structural member (imperfect shape), structural imperfections (loading eccentricity, unknown boundary conditions) and physical imperfections (inhomogeneity, residual stresses). These three types of imperfections can be replaced by only one equivalent geometrical imperfection. The only way to find out the size of this imperfection is to carry out an experiment on flexural buckling and lateral torsional buckling. Equivalent geometrical initial imperfections were evaluated using Southwell’s plot of flexural buckling and lateral torsional buckling results. The amplitudes of those imperfections were statistically evaluated and with knowing of the 5% quantile of those amplitudes, it is possible to obtain parameters of Eurocode buckling curves.
Highlights
Structural glass has been established as a material of load carrying members in the end of twentieth century and its importance still grows [1]
This paper deals with initial geometrical imperfections of the structural glass members made of flat glass
In the case of structural glass members with problems of lack of stability, it is necessary to know the shape and size of the initial geometrical imperfections to carry out a static design
Summary
Structural glass has been established as a material of load carrying members in the end of twentieth century and its importance still grows [1]. Equation (1) [3, 4] describes (according to the second order theory) dependency of deformation f(w0)x of axially loaded imperfect column and bended beams (Figure 1a) on amplitude of initial imperfection. Methods Measured specimen was fixed in a vertical position (due to dead load deflections elimination) and supported by two timber blocks according to EN 1863-1 and EN 12150-1. Initial geometrical imperfections (global bow) were measured on specimens listed in table 2. The geometrical imperfection of the guiding rail was deducted from measuring the initial shape imperfections of the same glass specimen twice: once in the conventional location and once in the mirrored location. Using this principle, the shape of imperfection of the guiding rail u0,rail(x) was determined with (2). The shape of initial imperfections from all measurements is similar, but on the other hand, the amplitudes are relatively different
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