Load sharing in insulated double glass units : determination of the air pressure in the cavity due to mechanical and thermo-mechanical loads

Glass is an indispensable building material because of the special properties. Glass has a low heat resistance and therefore it is a thermal leakage in the outer wall. Insulated double glass reduces the heat transfer tremendously. The closed air in the hermetically closed cavity is a good insulator. The magnitude of the pressure in a hermetically closed cavity is an unknown parameter. What is the cavity pressure if the temperature changed, ambient pressure changed, under a uniformly distributed load, under a concentrated load and the like? These influences were investigated by an analytical model and were verified by experimental research

Load sharing in insulated double glass units : determination of the air pressure in the cavity due to mechanical and thermo-mechanical loads

Glass is an indispensable building material because of the special properties. Glass has a low heat resistance and therefore it is a thermal leakage in the outer wall. Insulated double glass reduces the heat transfer tremendously. The closed air in the hermetically closed cavity is a good insulator. The magnitude of the pressure in a hermetically closed cavity is an unknown parameter. What is the cavity pressure if the temperature changed, ambient pressure changed, under a uniformly distributed load, under a concentrated load and the like? These influences were investigated by an analytical model and were verified by experimental research

Structural design for ponding of rainwater on roof structures

Ponding of rainwater is a special load case that can lead to roof collapse. In Dutch building practice the most frequently occurring damage cases are failures of flat roof structures caused by ponding of rainwater. In the Dutch code for loadings and deformations NEN6702 [1] and the Dutch guidelines for practice regarding ponding NPR 6703 [2], principles and guidelines for the determination of rainwater loads are given. The Dutch code [1] prescribes a complex iterative procedure for ponding of rainwater. Today, there are a number of computer software programs available to support the structural designer in this iteration method. However, to keep insight in the process of rainwater ponding, a simple design method for ponding of slightly sloping flat (steel) roof structures was developed. The method is described in the first part of this article. In the second part a sensitivity analysis for design and construction inaccuracies is presented. It is shown that roofs, that are seemingly stiff enough to withstand ponding, need partial safety factors substantially greater than normally used to account for construction inaccuracies. A proposal for the partial safety factor related to roof stiffness and construction inaccuracies is given

Concrete shell structures revisited : introducing a new and 'low-tech' construction method using vacuumatics formwork

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Segmented Barrel-Vaulted Glass Roof

A structural system for segmented barrel-vaulted glass roofs has been developed,aiming at maximum transparency due to structural optimization. This has led to astructural system with small connections, integrated into the glass, as well as clear,transparent joints. Finite element analysis and a full-scale test has been performed,showing PVB-laminated glass, 101010.4, could be sufficient to create spans up to20 meters with slightly prestressed cables measuring just 3 mm in diameter

Discrete Element Modelling of VACUUMATICS

Vacuumatics consist of independent particles inside an airtight enclosed membrane, that are prestressed due to a difference in (air) pressure. Analytical and numerical research of vacuum prestressing has illustrated that the effective prestressing forces can be divided into two interrelated prestressing components. Due to the granular characteristics of Vacuumatics, the material behaviour can be modelled by means of the Discrete Element Method (DEM). The individual prestressing components acting on the edge particles of vacuumatic structures can be simulated by means of a specialised Atmospheric Pressure Model in HADES (by Habanera). Analytically defined equations form the basic input in this simulation process. These simulations enable us to analyse (visually as well as numerically) the prestressing forces, but also the contact forces and the displacements of each particle due to this vacuum prestressing. Furthermore, bending phenomena of beam-shaped Vacuumatics can be analysed in detail, providing us with insight to describe and predict the structural properties of any type of vacuumatic structure

VACUUMATICS; Systematic Flexural Rigidity Analysis

The structural integrity of vacuumatics relies on the principle of prestressing unbound particles inside an enclosed membrane. By introducing a negative pressure (partial vacuum) inside this airtight flexible enclosure, the membrane is tightly wrapped around the outer particles, hence effectively bonding the particle filling to create (adaptable) load-bearing structures. Analytical and numerical studies on the fundamental prestress derivation of vacuumatically prestressed structures have shown that the effective prestressing forces between the particles largely depend, apart from the differential in (air) pressure differential, on the elastic properties of the skin material. The flexural rigidity of vacuumatics is mainly determined by the material properties of the particles and membrane used. Variations in elasticity of the skin and particle filling, and with this the shape, size, compressiveness, roughness, and packing density of the individual particles, highly influence the structural behaviour of vacuumatic structures. In order to explore the influence of different particle and skin characteristics (or parameters) on the flexural rigidity, experimental research has been carried out by means of four point bending tests. Different types of particles were used to discover behavioural trends dependent on the parameters varied. The results of this study provide an enhanced understanding of the true overall structural response of vacuumatics. By systematically elaborating the different parameters, we are able to determine what specific material properties are desired to design the ‘most efficient’ vacuumatic structure for every application