Building Science最新文献

This paper presents a simple approximate method of calculating surface temperatures resulting from a repeated square wave heat input to a room. The calculated values are shown to give reasonable agreement with results obtained on an electrical analogue. Values of thermal impedance for single and multi-layer walls are tabulated.

The continuous connection method is employed to analyse the free bending and torsional vibrations of regular symmetric cross-wall structures. The natural modes and frequencies of vibration are determined from the Galerkin technique. The theoretical analysis is illustrated by a numerical example of a typical representative structure.

The structural behaviour of reinforced and prestressed concrete beams made of expanded slate lightweight aggregate (Solite) concrete is discussed in relation to strength, cracking and deformation characteristics. The beams were designed to have permissible concrete stresses of 15·0–26·0 N/mm², and the cube strength of the concrete was 35–40 N/mm² in one day and about 50 N/mm² at 28 days. The deflection, cracking and the strength characteristics of the beams have been studied throughout their flexural loading range, and their mode of failure. It is shown that Solite lightweight concrete beams possess adequate ductility and load factor, and satisfy all the serviceability requirements of current Codes of Practice.

Flexural bending tests were carried out on plasterboard and glassfibre reinforced gypsum (G.R.G.) samples which had been heated for several days to 105°C, and compared to similar results on matched samples which had not been heated. G.R.G. material with well-dispersed glass fibres showed a significantly greater initial strength and also a greater loss of strength after heating, when compared to material with poorly dispersed fibre reinforcement. Standard plasterboard (gypsum baseboard) was much weaker than G.R.G. and also lost some strength on heating.

The limitations of existing methods available for the assessment of environmental wind conditions around buildings, using wind tunnel models, are discussed. The development of an alternative instrument which, in many situations, is more suitable than those more commonly used, is described. A drawing, circuit diagram and calibration curve for the instrument are presented and its limitations and future development outlined.

The results of an experimental study of the influence of a flexible support on a model of a folded plate structure, continuous over two spans are presented together with a comparison between the recorded stresses and those obtained by applying two methods of analysis generally known as the approximate and the elastic methods. Also included is a comparison between the results of other published experimental tests and the corresponding theoretical values computed by applying the elementary method. General comments and conclusions which can be of some value for design purposes, are reported.

One of the architectural requirements of the tinted laminated glass used in the construction of the Sydney Opera House glass walls was that it should be uniform in colour relative to an initially accepted colour standard. As the glass was manufactured in small batches over a two year period, stringent controls were needed to maintain the necessary colour quality of the laminate. The procedures adopted to check uniformity of colour are described and results are given of colorimetric analyses carried out on the colour standards and the production control specimens. The chromaticity data are interpreted in terms of subjective colour discrimination and are shown to be compatible with visual observations of the glass in situ.

The growing demand for cement in most countries necessitates long range planning of cement production. Such planning must be based on economical and technological analysis of various cement consuming factors. The paper presents analysis of cement requirements for different types of buildings, public works and other uses and also estimates the possible change in these requirements due to anticipated technological innovations.