Building Science最新文献

Water vapour can be lost from an enclosure by ventilation, by diffusion through the fabric, and by condensation on or within the fabric. These mechanisms can be represented by a vapour flow circuit. Expressions are given for the conductances and vapour pressure sources associated with condensation. An example is given.

A theoretical and experimental study of the elastic rigidities of slabs with circular voids oriented in the longitudinal direction only is discussed. Equations are presented for predicting the flexural and torsional rigidities of the slabs. Test results on slabs with different void depth ratios are shown to be in good agreement with predicted values.

This paper identifies the significant role which statistics and probability theory can play in the design of many building subsystems. It shows possible improvements in the current methods of design of these individual subsystems as well as the benefits to the total building design if the probabilistic implications are acknowledged.

The paper discusses the development of computer design and optimisation systems for existing construction systems. While the basic frame and methodology of the computer system remain unchanged, parts of it, such as the contents of data banks and static analysis modules can be replaced by modules suiting different construction systems.

The time and cost of such a small system together with work spent on replacing several modules is less than that of the development of a large, general building design system and its maintenance.

An algorithm to generate layout plans of flats and building sections composed of several flats is discussed. Two different examples of such small systems are presented.

The increased use of rectangular hollow section tubes in the fabrication of lattice girders has focussed attention on the joint problem. Previous elastic analyses, although useful in determining the onset of local yield, gave no real estimation of the strength of the joint. This paper presents a method of evaluating the static collapse load of a gap joint, based on the widely used yield line approach for the analyses of reinforced concrete slabs. The theory enables a quantitative estimate of the relative significance of the joint parameters to be made.

In the stiffness analysis of plane interconnected shear walls, it is convenient to specify the degrees of freedom at nodal positions defined by the intersection of the centroidal axis of each interconnecting beam and the centroidal axes of the shear walls. These intersection points are positioned a finite distance away from the ends of each interconnecting beam.

A modified stiffness matrix is presented for an interconnecting beam which includes a rigid arm at each end to allow for this finite distance, rotational springs to account for the localised deformations which take place in the zones where the beam adjoins the shear walls and transverse shear springs to allow for shear deformations in the beam. The matrix is presented in a form which permits existing computer programs to be modified with ease.

A stiffness program employing this matrix is used to analyse a series of plane interconnected shear walls, previously tested by MacLeod, in which the beam depth was varied from model to model. The model showing the greatest sensitivity to localised effects was reanalysed keeping the beam depth constant, but varying the number of storeys and in consequence the height of the structure.

The results are presented to show the importance of the rotational springs to the accuracy of the mathematical model and are compared with experimental evidence.

In the present technical note, the drag characteristics of two-dimensional wall-mounted circular cylinders and equiangular prisms (wall bodies) are reported. Comparison of drag data for model mounting with and without end gaps are made at identical blockage ratios. Visual observations indicate that the lower forebody pressure for wall body model is caused by appreciable deflection of the flow approaching this model. For models with finite end gaps this flow deflection is not excessive at comparable blockage. This causes the drag force to be lower for wall bodies. When the wall body is in the form of a circular cylinder, Reynolds number effects should be considered besides blockage.