Building Science最新文献

In the past a number of theories have been put forward to predict the moment strength of reinforced concrete slabs. These theories, summarised elsewhere[1] were developed by making assumptions on the mode of failure of the reinforcing steel bars crossing a yield line. Unfortunately there has been very little experimental work undertaken to verify the assumptions used to develop these theories, and what little has been undertaken is unreliable due to inadequate experimental techniques. The present paper describes a significant experimental investigation on the mode of failure of under reinforced concrete slabs subjected to combined bending and torsion.

Tests on lightweight aggregate (Lytag) and gravel concrete beams under sustained loading are reported. It is shown that deflection and crack widths under sustained loads are greater in lightweight-aggregate concrete beams than gravel concrete beams and that when a proportion of the shrinkage had taken place before loading, ultimate deflections and crack widths are smaller than if no shrinkage had taken place.

Equations are given that describe the passenger capacity of paternosters and related growth of queues at landings. Specific results for random interfloor traffic are presented, with a discussion on the characteristics of paternoster performance under this type of loading.

Two post-war multi-storey buildings in Hong Kong were condemned and subsequently demolished, and another one was extensively repaired, all due to the serious state of corrosion of steel reinforcement and crumbling of concrete covers caused by the use of seawater in mixing concrete. The mechanism of the damage was discussed in the context of the steel and concrete interaction as well as the environment in which the buildings were situated. The deterioration and damage of the actual buildings are reported and illustrated.

The inherent superiority of shearwalls, as the chief lateral load resisting elements in tall building, cannot be overemphasised; and a considerable amount of work has been done on the analysis of shearwall structures, in the last two decades. However, most of the work done so far has been devoted to either single storey shearwalls, or considerably tall shearwall buildings. It was felt, that the theoretical solutions obtained for tall shearwalls, may not be applicable to walls of intermediate height, i.e. two or three stories. Hence the present research project was undertaken, involving a number of carefully controlled and organised sets of experiments. Photoelasticity was used in general, and very interesting results were obtained. These have been presented in the form of design charts and curves, to make them readily applicable in the design office.

Tests are reported on the flexural behaviour of high strength reinforced and prestressed concrete beams in terms of strength, cracking and deformation. The beams were made from concrete having a cube strength of 85–110 N/mm². The working stress in concrete varied between 27·7 N/mm² and 34·5 n/mm², and that in steel between 230 N/mm² and 345 N/mm². The results show that high strength concrete beams possess adequate load factors, and show ample warning and ductility prior to failure. The crack widths under design loads are within acceptable limits, although steel working stresses of 345 N/mm² may result in excessive long-term deflection. The strength and deflection can be satisfactorily predicted by existing methods.

This paper presents the results of research into the stress distribution in circular arch-ribbed domes carried out at the University of Newcastle-upon-Tyne. Theoretical values for the base reactions of such structures are presented in the form of influence line diagrams which can be employed directly for the design of similar domes. The theoretical results are also compared with experimental values to confirm their validity.

This paper describes a special form of radiant strip heating which offers a suitable solution for the supply of housing and communal buildings with hot water and radiant heating, taking into consideration also the comfort criteria. The thermotechnical calculations are based on Kollmar's method, the design parameters were determined by measurements.

The paper presents an approximate analysis of cylindrical shells with edge beams. The shell is detached from the beams, and the deformations of the components are determined separately and equalized with the aid of supplementary forces—Shear Forces T_B=t_Bx and Transverse Forces Q_B (figure 1). The basic assumption is that the shell and beams are hinge-jointed and the beams are incapable of taking up horizontal forces.