B O O K REVIEWS

Shell and spatial structures engineer- ing, Proceedings of the international symposium on shell and spatial structures, COPPE, Federal University of Rio de Janeiro, Brazil, September 1983 Ed F. L. L. B. Came~to, A. J. Ferrante, R. C. Bat/sta and R. Lopez Pa/anco Pentech Press, London, 1984, 298 pp., £28.50

The s ta ted ob jec t ive of this S y m p o s i u m was to p r o m o t e an exchange of ideas and i n f o r m a t i o n on p r o b l e m s involving the design, c o n s t r u c t i o n and s tab i l i ty analysis of l ight spat ia l s t ruc tures . The vo lume is organized in to two par ts : Part 1 : c o n s t r u c t i o n of spat ia l s t ruc- tures wi th four papers ; and Part 2: s tabi l i ty and s ta t ic analysis of spat ia l s t ruc tu res wi th 13 papers. The overall qua l i ty of the p r in t ing and i l lus t ra t ions is good , cons ider ing t h a t the b o o k has been p repa red f rom typed , camera- r eady manusc r ip t s .

The four papers in Part 1 deal wi th the analysis of m e m b r a n e s t ruc tu res ; the gene ra t i on of a new s t ruc tura l fo rm the star b e a m ; the analysis , design and c o n s t r u c t i o n of a space f rame shell; and a sof tware package for steel s t ruc tures . Each paper is in te res t ing and in format ive , especial ly to' t hose engaged in the prac t ice of s t ruc tu ra l design.

Part 2 con ta ins several papers which would be of p r imary in teres t to researchers , pa r t i cu la r ly in the area of s tab i l i ty where th in-wal led curved beams; HP gable shells; in f la tab les ; cy l inders ; and f ramed spherical shells are examined . Analy t ica l , numer ica l , and e x p e r i m e n t a l s tudies are inc luded and some of the papers con t a i n s impli f ied fo rmulae t ha t could also be o f in te res t to designers.

The remain ing papers in Part 2 t rea t a var ie ty of subjec ts inc lud ing design m e t h o d s for cab le- re inforced m e m b r a n e s , h igh rise p n e u m a t i c s t ruc tu res and me ta l hypars . Also, the plast ic analysis of n o n p r i s m a t i c fo lded pla te s t ruc tu res and the analysis of ax i symmet r i c shells wi th local i r regulat i t ies are t rea ted. For the mos t par t , this g roup of papers would be of in te res t to researchers and designers of special ized s t ruc tu ra l fo rms and types.

In conc lus ion , the vo lume addresses the s ta ted objec t ives of the s y m p o s i u m very well. Li t t le of the c o n t e n t is a r e s t a t e m e n t of we l l -known t e x t b o o k mater ia l ; r a ther , several papers embrace the cu t t ing edge of t e chno logy in the s t ruc tu ra l engineer ing of shell anti spat ial s t ruc tures , and the book would

be a w o r t h while acquis ion for those in te res t ed in this field.

Phill ip L. Gould

Understanding structural analysis David Brohn Granada Technical Books, London, UK, 1984, 282 pp., £9.95

Those of us who are acqua in t ed wi th David B r o h n will recognize m u c h of his ind iv idua l i ty in this new text . There is the clari ty of express ion which we have c o m e to expec t f rom h im, the effect ive use o f easily under - s tood diagrams, a creat ive a t t i t ude to the p r o b l e m s of c o m m u n i c a t i o n which mot iva t e s h im to t ry a new f o r m a t and above all the emphas i s on the i m p o r t a n c e of u n d e r s t a n d i n g s t ruc tu ra l behaviour .

Many of the papers which have been p resen ted in this area in recen t years have, s o m e w h a t regre tab ly , t e n d e d to ta lk a b o u t qua l i ta t ive analysis as if it were a separate act ivi ty a l toge ther . This t ex t begins u n a s h a m a d l y wi th an ini t ia l exp l o r a t i on of the subject area which is pa r t ly qua l i ta t ive and par t ly algebraic. And we are immedia t e ly aware of the advantages of seeing the subjec t , in this way, as a unif ied enti ty.

For this is a t ex t for learners ; it is p resen ted as a resource to assist a learner as he strives to f ind ou t what s t ruc tu ra l analysis is all abou t , and should be all abou t . In mos t cases it is ful ly deta i led and an t ic ipa tes m a n y of the more c o m m o n errors and mi sunde r s t and ings which f rus t ra te learners. And the generous provis ion of careful ly prepared diagrams does m u c h to enhance the usefulness of the tex t , The fo rma t , a l t h o u g h r a the r d i f fe ren t f rom tha t of a s t andard text book , uses famil iar d iagramat ic con- ven t ions . It t he re fo re presen ts the reader wi th few p rob l ems in assimila- t ion, once he has b e c o m e a c c u s t o m e d to a l t e rna t ing f r e q u e n t l y be tween tex t and diagram.

It is wr i t ten for those who are s tudy ing the subjec t for the first t ime; for that reason it is inev i tab ly less sui table as a re ference text . Each chap te r flows f rom beginning to end in a c o n t i n u o u s exp lana t ion . There are few overall summaries , and no p u n c t u a t i o n in the form of main headings. The exp lana t ions , because they are full, are less suited to revision than they are to initial s tudies. And the i m p o r t a n t asser ta t ions which are made al a n u m b e r of po in t s in the text are nol always expla ined, or cross-

referenced to the sect ions where an e x p l a n a t i o n is to be found .

There is some incons i s tency be tween the descr ip t ions of the target reader- ship and the c o n t e n t of Chap te r 1, where the decisions wi th regard to expla in ing f u n d a m e n t a l concep t s or taking t hem for gran ted appear to be s o m e w h a t arb i t rary . Some readers (and the i r teachers ) will be pe r tu rbed by the descr ip t ion of m o m e n t s as forces, jus t as they will no t immedi - ately iden t i fy reac t ions as in te rna l forces especial ly when the term is no t expla ined.

There is a p red ic t ab ly m o n o t o n o u s p a t t e r n in the style of tile wr i t t en passages which is unl ike ly to b o t h e r a new learner , because he will no t read t h r o u g h the en t i re book in a shor t pe r iod of t ime, as you r reviewer did. But some of the var ia t ions in the text i n t roduce confus ion , r a the r t han var ie ty ; there seems l i t t le po in t in referr ing to vi r tual d i sp lacements , d e f o r m a t i o n s and def lec t ions in one page, when each phrase appa ren t ly means the same -- but when an earnes t reader might feel jus t i f ied in seeking an u n d e r s t a n d i n g of the subt le dist inc- t ion which he p resumes the wri ter is making.

If this is a t ex t for learners, t hen the style of assistance given in the exp l ana to ry chapte rs should con t inue over into the worked so lu t ions to the prac t ice p rob lems . Here, however , the re is an u n f o r t u n a t e d iscrepancy. A learner is given quan t i t a t i ve com- p u t e r o u t p u t s for p rob lems which he was encouraged to solve quah ta t ive ly - and these do no t always fo l low the draf t ing style which he was encouraged to use in tire fol lowing ins t ruc t ion . It might have been be t t e r to give the s u p p l e m e n t a r y i n f o r m a t i o n t w h i c h is a d m i t t e d l y in te res t ing it no t valuable) in a separate append ix .

Overall, I had two i m p o r t a n t reserva- t ions abou t this new t e x t b o o k . The first was the re la t ively speedy coverage which it gave to a n u m b e r of topics which have always seemed to in t roduce diff icul t ies for undergradua tes . I have in mind the concep t of a couple, the na tu re of a hinge, the idea tha t the slope of a bend ing m o m e n t diagraln will be the same on bo th sides of a hinge, the na ture of a rigid corner in a f rame, the reason why the bending m o m e n t t ransfers a round it and the whole concep t of the free body diagram. At a later stage in the text I was also s l ruck by the s o m e w h a t s implis t ic way in which the learner was in t roduced to vir tual work. and by the disregard of the valid ques t ions which m a n y of len ask abou t the der iva t ion of the two theorems.

I was also acute ly aware of t h e abs t rac t na ture of the ent i re presenta- t ion of the topic. From tire very first

148 Engng Struct., 1985, Vol. 7, April

page, this book is concerned with schematic representations of structures. It seems a pity, to put it mildly, that the man who has done so much to persuade teachers and students of the need to understand the behaviour of real structures should devote his text book to the understanding of dia- gramatic models of structures.

Students should be encouraged to use this text book, either for their initial learning or - if that is not expedient in their department - to enrich that learning and to make good the omissions in it.

John Cowan

Limit analysis and concrete plasticity M. P. Nielsen Prentice-Hall, Englewood Cliffs, N J, USA, 1984, 420 pp., £40.80

The application of the concept of plasticity to structural concrete has a long history. Design methods were frequently developed in isolation from the mainstream of the theory of plas- ticity. Pioneers, such as Ingerslev and Johansen in Denmark, Gvozdev in the Soviet Union and A. L. L. Baker in Britain, developed methods of analysis and design which incorporated the special features of structural concrete but generally did not demonstrate the relationship that their methods had with, for example, the theoretical developments of the mathematical

theory of plasticity which flourished later at Brown University in the United States and at Cambridge University in England.

Nielsen's book attempts to relate the special developments in limit analysis of structural concrete to the now classical theory of plasticity and so to facilitate the further development of his subject on a firmer less empirical basis.

The first chapter is devoted to a short overview of the theory of plasticity and this is followed by an important chapter on yield conditions. The third chapter is devoted to the theory of plain concrete, whilst the fourth is concerned with disks and is primarily based on work done by the author 15 years ago. The fifth chapter is concerned with beams and it is perhaps surprising to find that beams in flexure receive very little at tention due presumably to the full coverage that this topic has received elsewhere in the technical literature. A much fuller treatment is given of beams in shear followed by a compact presenta- tion of torsion and then combined bending, shear and torsion are dis- cussed.

The sixth chapter is a very impor- tant one on slabs and rather naturally gives full discussions of the yield line method and the strip method. The punching shear of slabs is the topic of the seventh chapter whilst the eighth chapter is concerned with shear in joints. The ninth and last chapter is

devoted to the bond strength of rein- forcing bars. The book concludes with a very full list of references arranged historically from Galileo's 'dialogue concerning two new sciences' of 1638 up to work by the author written in 1983 and still unpublished when the book went to press. The recent refer- ences are overwhelmingly from Danish s o u r c e s .

The book is well-produced and con- tains a large number of clear diagrams. The cited material has naturally been selected from the subject areas closest to the work of the author. The chosen areas are treated authoritatively but a surprising omission is any considera- tion of frames and this was presumably inevitable after the very brief coverage of beams in bending. Computational procedures receive only passing refer- ence.

The book is a very significant addi- tion to the literature and makes one even more conscious of the importance of the Danish contributions to this subject area. It is unlikely to be adopted as a class text - partly because of its cost - but it will be very valuable to advanced students, researchers and to many designers. It will assist in dis- seminating a better understanding of the behaviour of reinforced concrete at rupture and in the more general adoption of less empirical design methods.

J. Munro

Engng Struct., 1985, Vol.7, April 149