Building Science最新文献

This paper reports the use of soft laterite as fine aggregate in structural concrete. The modulus of elasticity of $\text{1:1}\text{1}\text{2}\text{:3}$ by weight of concrete mix which contained soft laterite as fine aggregate was 1840 kg mm⁻² (2·62 × 10⁶ lbf in⁻²) as compared with the modulus of elasticity of normal concrete mix of $\text{1:2:4}$ of 2025 kg mm⁻² (2·88 × 10⁶ lbf in⁻²), whilst the compressive strength was 2·47 kg mm⁻² (3525 lbf in⁻²) against 2·82 kg mm⁻² (4000 lbf in⁻²) for normal $\text{1:2:4}$ mix.

The effect of exposure to high temperature of concrete which contained laterite is about the same as that for normal concrete for various mixes considered in the tests.

Two rectangular reinforced concrete beams were tested to pilot further investigations: one with normal concrete mix of $\text{1:2:4}$ and the other with the concrete $\text{1:1}\text{1}\text{2}\text{:3}$ with soft laterite as fine aggregate instead of sand. The ultimate moments of resistance of the two beams are almost the same although the beam of normal concrete offers greater flexural rigidity throughout, and deflexions of the beam with $\text{1:1}\text{1}\text{2}\text{:3}$ mix with laterite fines deflected about twice as much as the normal concrete beam of $\text{1:2:4}$ mix prior to the appearance of flexural cracks in both beams. The phenomenon still requires further investigation. The effect of creep on various types of structural elements cast with the concrete containing laterite fines instead of sand will need to be studied before concluding on suitability of the material for structural work.

The use of computer programs for the layout planning of buildings requires some form of input data defining the relationships between activities. This data may be given on a derived rating scale (subjective data) or in terms of measured movement interchange (continuous data).

The collection of continuous data can be a time consuming and costly process. Experimental work using a generative (construction-type) layout planning program identifies the effects of varying the precision of continuous data and indicates that more approximate forms than those presently employed may yield acceptable layout solutions.

Paper presents prediction of probability of failure of prestressed concrete beams. Probable strengths of basic materials used in the beam are generated as random variables subject to code specifications and the probability of failure of the beam is obtained through explicit formulation. Probability of failure of beams designed by Indian code of practice and code of American Concrete Institute is illustrated through a set of examples. It is found that the probability of failure of a prestressed concrete beam is very sensitive to variation of steel and less sensitive to the variation in the strength of concrete.

The relevant Code of Practice gives no guide to the designer which enables him to assess the mean loads in a situation where there are unusual wind effects caused by the proximity of large buildings. The results presented here are those of a project undertaken to investigate the interference effects of a pair of square prisms on their mean lift and drag. Tests have been performed with the bodies both normal to and in-line with the flow. In addition, the wall proximity effects on the mean lift and drag on a single prism have been measured.

Because of the variability of natural soils, it is a difficult task to predict the performance of soil-cement blocks in practice, and a conservative approach must be adopted. Though time-consuming and severe, the A.S.T.M. durability test provides the best indication of the performance of soil-cement building under tropical conditions. Tests at low compaction energies on a wide variety o Zambian soils suggest, however, that the perdominant factor affecting durability is dry density. A correlation between these two properties may be used, with an appropriate margin of safety, to introduce great simplification into procedures or selecting soils for making soil-cement blocks.

The dynamic response of a large building floor system, as induced by humans, has been experimentally evaluated. The human reaction to this response was related as an unsafe or unpleasant feeling. The subsequent dynamic analysis of the floor indicates that the natural frequency and induced frequency are of the same order, thus the reason for the resonance problem. The dynamic analysis, experimental study, static analysis and recommendations for eliminating the resonance problem is discussed.