Response of Members Subjected to Flexure Flashcards
What are the stages involved in the response of prestressed members to flexure ie bending?
1 negative curvature….
Define camber
The upward deflection of a member due to eccentric prestressing
What causes downward deflection of a member?
Additional superimposed load
The strength of a prestressed section is controlled by the response where?
At a crack
When calculating load-deformation response in a prestressed member, should you account for post-cracking tensile stresses in concrete? Why?
Yes because deflection of a member is influenced by tensile stresses in the concrete
What two phenomena the flexural capacity of a prestressed member governed by?
Tensile yielding of prestressing strands at low levels of compression
and
Compressive crushing of concrete at high levels of compression
What causes the P-delta effect in slender columns?
The addition of moment Pe due to eccentric compression force and moment caused by deflection and compression force P-delta
For short columns, is the P-delta effect substantial?
No, it is negligible
For longer columns, how does the P-delta effect affect the moment M and the axial force N
Moment will increase faster than axial load
For very long columns, how does the P-delta effect affect the moment M and the axial force N
Mmax will increase before forces at mid-height reach failure envelope
What is second-order analysis
Structural analysis which accounts for the change in section geometry due to deformations
What does the acronym MAD represent?
Moment At Deviated point
ie take moments about the point which has deviated from the tangent (straight line drawn under the max bending moment
Complete the 1st Moment Area Theorem
….is the area under the curvature diagram
….tba
Complete the 2nd Moment Area Theorem
….is the area under the curvature diagram
….tba
List the steps involved in calculating the deflection of a prestressed member subjected to flexure
1 draw the bending moment diagram
….tba
