FREE BOOKS

Author's List




PREV.   NEXT  
|<   92   93   94   95   96   97   98   99   100   101   102   103   104   105   106   107   108   109   110   111   112   113   114   115   116  
117   118   119   120   121   122   123   124   125   126   127   128   129   130   131   132   133   >>  
the paper, he should not have attempted to criticize it. What the writer presented for consideration was more than his opinion of the matter. In fact, no opinion at all was presented. What was presented was tests which prove absolutely that longitudinal rods without hoops may actually reduce the strength of a column, and that a column containing longitudinal rods and "hoops which are not close enough to stiffen the rods" may be of less strength than a plain concrete column. A properly hooped column was not mentioned, except by inference, in the quotation given in the foregoing sentence. The column tests which Mr. Turner presents have no bearing whatever on the paper, for they relate to columns with bands and close spirals. Columns are sometimes built like these, but there is a vast amount of work in which hooping and bands are omitted or are reduced to a practical nullity by being spaced a foot or so apart. A steel column made up of several pieces latticed together derives a large part of its stiffness and ability to carry compressive stresses from the latticing, which should be of a strength commensurate with the size of the column. If it were weak, the column would suffer in strength. The latticing might be very much stronger than necessary, but it would not add anything to the strength of the column to resist compression. A formula for the compressive strength of a column could not include an element varying with the size of the lattice. If the lattice is weak, the column is simply deficient; so a formula for a hooped column is incorrect if it shows that the strength of the column varies with the section of the hoops, and, on this account, the common formula is incorrect. The hoops might be ever so strong, beyond a certain limit, and yet not an iota would be added to the compressive strength of the column, for the concrete between the hoops might crush long before their full strength was brought into play. Also, the hoops might be too far apart to be of much or any benefit, just as the lattice in a steel column might be too widely spaced. There is no element of personal opinion in these matters. They are simply incontrovertible facts. The strength of a hooped column, disregarding for the time the longitudinal steel, is dependent on the fact that thin discs of concrete are capable of carrying much more load than shafts or cubes. The hoops divide the column into thin discs, if they are closely spaced; widely spaced h
PREV.   NEXT  
|<   92   93   94   95   96   97   98   99   100   101   102   103   104   105   106   107   108   109   110   111   112   113   114   115   116  
117   118   119   120   121   122   123   124   125   126   127   128   129   130   131   132   133   >>  



Top keywords:

column

 
strength
 

spaced

 

concrete

 

presented

 

compressive

 
hooped
 
lattice
 

formula

 
opinion

longitudinal

 

incorrect

 

simply

 

widely

 

element

 

latticing

 

varies

 

section

 
common
 

account


strong

 

varying

 

stronger

 

compression

 
deficient
 

include

 
resist
 

disregarding

 

incontrovertible

 
personal

matters

 

dependent

 

capable

 

divide

 

closely

 

shafts

 
carrying
 

benefit

 

brought

 

quotation


foregoing

 

criticize

 

inference

 

mentioned

 
sentence
 
attempted
 

relate

 

columns

 
bearing
 

presents