NEW GROUND BROKEN BY POWERFUL ARCHITECT'S AID
Sinclair machines are regarded still as little more than toys. David Marsh disagrees in this review of a new cassette.
APART FROM generalised spreadsheet programs of the Vu-calc and Vu-file variety, there has been little or no Spectrum software written for serious commercial applications. Something of a new departure in that direction is a specialised program, Beamscan, which is used to calculate the sizes of steel beams used in building construction.
The program is used interactively, with the screen prompting the user at all stages and asking for details of the loads. A diagram of the beam is displayed on-screen, which makes it clear exactly what information is being requested by the computer. The program seems well error-trapped and user- friendly. When all the data is in, there is a wait of about one minute while the numbers are crunched and then diagrams are displayed giving shear force and bending moment along the beam.
From its library of standard steelwork sizes, the program recommends a choice of up to eight suitable sections with stress and deflection for each. All the regular rolled steel joists, universal beams, universal columns and rolled steel channels in grade 43 steel are featured and a moment of inertia can be obtained for timber beams, from which it is a simple matter to choose a suitable section.
The beam must be simply-supported and single span. Cantilevers are not within the scope. That is perhaps the only limitation worth mentioning. Any combination of point loads, distributed loads and uniformly-tapered loads in any number up to a total of 99 can be specified.
What is more, the distributed loads do not have to extend to the end of the beam. Within the designated span of 0.3 to 20 metres, it is difficult to visually any beam which could not be analysed by the program.
Point loads frequently consist of the end reactions of other beams. Both end reactions are given, which covers that point and also is a great help in finding the stress in any supporting brickwork. Also given are the maximum bending moment and shear force, the deflection co-efficient, the permitted deflection and optimum moment of inertia.
That would mean that other types of beams, for example round or rectangular hollow sections, could then be chosen using the data given in BS4.
For each beam size chosen, the L/ry and D/T ratios are given, together with permissible and actual stresses, actual shear stress and deflection.
All that information can be put into the form of a calculation sheet using the ZX printer. That can then be submitted to the client or to the local authority responsible for checking the design. Although full data is given on the results and the presentation is clear and concise, perhaps some local authorities may consider it a little too concise, in that virtually no details are given on how the answers are obtained. It is therefore difficult to check the accuracy.
It is clear, however, from the printout whether or not the correct data has been typed-in and, of course, that is half the battle. The fact that a computer printout is being submitted rather than the more usual written calculations should lend a reassuring air of professionalism.
It is also probable that in the perhaps not-too-distant future when most calculations are made in this fashion, various programs will become widely-known and generally accepted in the profession as being accurate. Some kind of type-approval system might even be possible so that checking would be limited to the data output.
That would be in line with the procedure followed in other areas, where certain materials, for example building blocks, are given a certificate to indicate that they comply with building regulations. If that make is used, then no further proof is required that they meet the requirements. Extending the concept to software seems logical and almost inevitable.
Beamscan is supplied recorded on both sides of the cassette and is suitable for a 48K Spectrum, being about 35K. It is supplied with a well-written manual which guides the user through a worked example and describes the limitations of the program as 999KN for each load to a maximum total load of 10,000,000KN from the 99 loads mentioned. They scarcely seem like limitations when there are other costlier beam design programs for bigger computers which cater for a maximum of right point loads while others cannot calculate the shear force or bending moment.
At £25, it appears costly compared to the usual programs in Sinclair User but it is a more specialised item with a lower volume sale than games or spreadsheets and is much less expensive than anything comparable.
It should be ideal for small architectural practices or the many one-man firms involved in smaller-scale building works. Neither is it necessary to pay a four-figure sum for the computer. The whole system - 48K Spectrum, ZX printer, TV, tape recorder and software - can be up and running for slightly less than £300 and will soon pay for itself in time saved.
Beamscan is available from Beamscan, 20 Vaughan Avenue, London, NW4 4HU. Tel: 01-202 8656.