Structural Engineering Reference Manual development length question

[Mr. Bean]

Hey guys, I am using the 8th edition of the SERM by Alan Williams and I had a question about something they mention on page 1-40 about development length in compression. So they give the actual ldc value which I understand but then they say that the actual development length ld is obtained by multiplying by certain factors. Are they referring to development length of bars in a column when under tension?

Thanks.

 

[StructEngBrah]

No, they are referring to bars that are only in compression on page 1-40.  If you have a column where the bars can be in tension or compression you need to design the development length for the worst case.  For bars in compression only, your starting point for development length is the ldc value.  You are allowed to reduce the development length using those factors shown on page 1-40 (excess reinforcement factor and confinement factor).   If none of those factors are applicable, then the development length for a bar in compression only is ldc.

 

[Mr. Bean]

No, they are referring to bars that are only in compression on page 1-40.  If you have a column where the bars can be in tension or compression you need to design the development length for the worst case.  For bars in compression only, your starting point for development length is the ldc value.  You are allowed to reduce the development length using those factors shown on page 1-40 (excess reinforcement factor and confinement factor).   If none of those factors are applicable, then the development length for a bar in compression only is ldc.

Oh I see, I was confused about that. Thanks for the reply.