Civil Engineering/cantilever beam


what is the concept of back span of cantilever beams.Why is it necessary.Wont a cantilever stand if the column supporting the cantilever beam is designed to support the moment coming from the beam. Or if the cantilever beam is supported on another beam, then wont it stand without backspan if the main beam is designed for torsion.

Also,how does moment release in columns work.If i provide a beam between two columns, and give moment release to one of the columns(say major axis moment release), will all the negative moment shift to ghe other column?

Dear Hani

Thre are no obliguation to have a back span for a cantilever but it provides more reliable design. The release of moment in one column will provide the other column with greater moment. This is an analytical conclusion which can be tested by yourself.


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Babak Esmailzadeh Hakimi


I can answer questions in Structural Engineering, Earthquake Engineering, Project Management and Project Control topics!


I am experienced in the area of earthquake engineering in electrical power industry, i.e. Lifeline Earthquake Engineering. My focus has been on structural seismic design of power installations. Recently I have got involved in project management in the category of constructional engineering.

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Bs degree in Civil Engineering from Ferdowsi University ,1988, Mashhad Iran, Ms degree in Earthquake Engineering, Sharif University of Technology, 1993, Tehran, Iran

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