Building Science最新文献

A project was undertaken to determine sequences of climatic data of a few days which can be used as design data for determining extreme indoor temperature, or alternatively the plant capacity necessary for heating or cooling a building to maintain a desired indoor temperature profile. A response factor computer program has been used with actual climatic data to estimate indoor temperatures continuously over a period of six years in Melbourne, to determine such sequences of days for design purposes. The number of days of design data necessary varies with the type of building. Of the various climatic elements required for such an exercise at other locations, solar radiation at say hourly or three-hourly intervals is one parameter that may not be available. A comparison is made of the results obtained with estimated clear sky solar radiation and actual measured solar radiation, and the relationship between the two explored.

An elastic analysis is presented for walls supported by either encastré beams or complete portal frames. The wall is idealised into a set of equispaced vertical stringers, which carry direct load, with shear carrying panels between them. Any distribution of vertical superload can be considered and the effect of wall self-weight may be included. A series of cases is analysed and the results are compared with those predicted by other methods.

The paper presents the results of experimental and analytical studies on ultimate strength of reinforced concrete beams with plain web under two-point load and axial force. The problem has been treated in the analysis as that of plain concrete under combined stresses. Seth's failure criterion has been employed and failure mechanism has been explained. Results of the tests, along with the results of previous investigators, have been verified with the proposed theory and have been found to be in excellent agreement.

Gypsum plasterboard, widely used for internal partitions in building structures, has been shown to suffer rapid dehydration when heated between 60° to 125°C in the laboratory, under humidity conditions representative of those found in normal buildings ($\text{≏13}$ mm Hg water vapour pressure).

This dehydration could have important consequences for the use of gypsum in some building situations, since loss of water leads to cracking, powdering and loss of fire resistance.

The turbulent air flow around a slab type building has been measured by Wise, Sexton and Lillywhite using a scale model in a wind tunnel. Using their data procedures are developed for calculating raindrop trajectories for droplets having radius r in the range 0 ≦ r ≦ 2500 μ with gradient wind speeds up to 26·8 m/s.

Grazing trajectories, for fixed droplet size, are obtained and from these the effective collision cross-section of the building is deduced. Employing the droplet size distribution of Best, for a given rainfall intensity, raindrop impaction rates over the building are evaluated. Approximate analytical methods are developed to predict impaction rates and their dependence on the building aspect ratio.

An elastic analysis, based on which most engineering structures are conventionally designed, is incapable of introducing the time factor into the design criterion. This paper attempts to show how the long time behavior of structures that creep may be investigated theoretically and to show how a basis for design for a definite span of life of bridge-like structures may be proposed.

The conventional finite strip analysis of plates, as developed by Cheung, considers bending deformations only, and is therefore inapplicable to the analysis of plates in which transverse shear deformations are important. Herewith a finite strip formulation which involves shear is developed. Numerical examples are then presented which demonstrate the applicability of the formulation to the analysis of thin, thick and sandwich plates.

The many methods for the non-destructive testing of concrete are reviewed. The methods are classified, though somewhat superficially, as surface methods, vibration and resonance methods, pulse propagation methods, radioactive methods and electrical and magnetic methods. The use of combinations of methods is seen as a significant development in the field. Other methods, some of which await exploitation, are discussed. It is concluded that unreasonable expectations for non-destructive test methods and a lack of trained technicians to apply them are the main reasons for their slow acceptance.