Discussion Overview
The discussion revolves around determining the Young's modulus for concrete using a beam subjected to third point loading. Participants explore the implications of using rupture load deflection versus elastic behavior in concrete, as well as the appropriate methods for calculating Young's modulus.
Discussion Character
- Technical explanation
- Debate/contested
- Mathematical reasoning
Main Points Raised
- One participant reports a calculated Young's modulus of 6.87 GPa, questioning its validity for concrete.
- Another participant argues that using rupture load deflection will yield a rupture modulus rather than Young's modulus, emphasizing that concrete does not behave elastically at high stress levels.
- It is suggested that to obtain Young's modulus, smaller load values should be used in varying increments, applying the deflection formula for a simply supported beam under mid-point load.
- A participant mentions that using a smaller load of 0.33 kN results in a Young's modulus estimate of around 9 GPa, which they still consider low.
- Another participant indicates that their calculations yield a range of Young's modulus values from 9 to 30 GPa, ultimately deciding to take the higher value of 30 GPa.
Areas of Agreement / Disagreement
Participants express differing views on the appropriate method for calculating Young's modulus and the implications of using rupture load deflection. There is no consensus on a definitive value for Young's modulus, as estimates vary significantly among participants.
Contextual Notes
Participants highlight the non-linear stress-strain relationship of concrete at higher loads, which complicates the determination of Young's modulus. The discussion reflects uncertainty regarding the appropriate load levels and methods for accurate calculations.