ICE - Institution of Civil Engineers - Virtual Library

From a review of existing knowledge of wind loads it is clear that, although many observations of wind velocities and pressures have been made, it is difficult to estimate their true significance with reference to the derivation of design loads. Velocities vary considerably over the wind front and fluctuate rapidly, and the pressures actually recorded may act on only a small area of a structure and for only a few seconds. Hitherto, practically no attention has been given to the time effect, and an attempt is made in this Paper to estimate the probable damage inflicted on a structure during a high wind. The damage is expressed in terms of the permanent plastic deformation and, hence, wind loads suitable for use in ultimate (plastic) design methods may be derived. Although some numerical results are given, it is found that available data on wind velocities and pressures are insufficient to enable full calculations to be made. The investigation shows clearly the nature of further research which should be under-taken in order to achieve a rational treatment of wind loading.

This Paper describes the design and construction of a large brick-lined reinforced-concrete drainage culvert for conveying cooling water and effluents from the I.C.I. factory at Billingham, Co. Durham, to the River Tees. Important features are the special arrangements made to enable the new drain to be connected into existing cast-iron drains with the minimum interruption to the running of the factory, and to enable sections of main drain to be readily isolated for subsequent inspection and maintenance. The design conditions, the types of culvert, and the outfall are deecribed, together with the method of construction, and an example is given of the flow conditions, cross-connexions, and penstock control required to effect one of the major isolations. The main control chambers are fully described and the various stages of the programme for putting the new drain into commission are outlined.

The special conditions associated with the drainage of cooling water from factories with a continuous process, and the advisability of providing in the early stages of design for the isolation of sections of drain for inspection and repair, will be apparent.

The first part of the Paper describes the major rivers of Khuzistan, the ancient irrigation systems, and the possibilities of reviving irrigation on a large scale in the province without deteriment to navigation on the Karun. Used in conjunction with the Ab-i-Diz, a tributary of the Karun, and the River Karkeh, the potentialities of a suggested impounding reservoir on the Upper Karun for irrigation, and for hydro-electricity and flood control in the province are described in general terms. The silt problem is also discussed.

The second part of the Paper describes certain deductions made on the regime of the Shatt el Arab. The rise and fall of the water-level in the inland delta of South Iraq is influenced by the obstruction to the flow of the Shatt el Arab caused by the discharge of the Karun, and the suggested impounding reservoir on the Upper Karun offers possibilities for flood control and land reclamation in South Iraq.

THE Paper outlines the more important considerations which influence the economics of electric transmission, more particularly long-distance transmission which may be associated with hydro-electric generation. The Authors consider that, although direct current may become competitive for transmission over particularly long distances, it is not practicable at the present stage of development to include reliable data concerning costs; the Paper is confined to consideration of overhead transmission of power at 50 cycles per second, alternating current.