Fracture point
The fracture point (similar to the yield point) describes a solid material’s elastic limit, which is the maximum stress per unit area it can withstand before there is permanent deformation or fracture. In other words, it is the limit of the material’s elasticity, for up to that point, the solid can resume its original shape when the load is removed; after that point, it undergoes permanent (plastic) deformation and will not return to its original shape even after the load (yield load) has been removed. For example where a timber beam might bow under a weight but will return to its original straight shape once the load is removed.
However no structural material exhibits perfect elasticity: depending on the type of structure and the material, permanent deformations are often unavoidable whenever loads exceed certain values. That is why engineers design structures to ensure the materials are being used within their elastic range and the loads involved will not produce permanent deformations. All structural materials behave plastically beyond their elastic range.
However, even if some materials show elastic behaviour, they may – after a long period of service, usually many years – exhibit a degree of plastic flow (or creep). In the example of the timber beam bowing, if the weight remains for sometime and is then removed the beam may remain bowed, showing signs of creep, this may also be the case with timber beams bowing over time from a combination of self weight, angle of cut and drying out.
On a graph showing a stress-strain curve, the point of the limit of elastic behaviour is called the ‘yield point’ and this is where plastic deformation begins – some of this deformation will be plastic and irreversible. In structural engineering, the yield point is regarded as a ‘soft failure’ mode which does not usually cause catastrophic or ultimate failure, it might be described as ductile fracture depending on the material, or a brittle fracture. This is effect the fracture point, where the material starts to break, either gradually or quickly, the behaviour depending on the material and stresses, the breaking point might be where a timber beam goes beyond, the yield, soft or ductile failure and brittle or fracture points to break and collapse.
[edit] Related articles on Designing Buildings
- Brittle fracture.
- Concept structural design.
- Detailed design.
- Ductile fracture.
- Elements of structure in buildings.
- Elasticity.
- Elastic limit.
- Moment.
- Stiffness.
- Structural engineer.
- Structural principles.
- Structural systems for offices.
- Structural vibration.
- Structures at the end of their design life.
- The development of structural membranes.
- Types of structural load.
- Vibrations.
- Yield point.
Featured articles and news
Retrofit 25 – What's Stopping Us?
Exhibition Opens at The Building Centre.
Types of work to existing buildings
A simple circular economy wiki breakdown with further links.
A threat to the creativity that makes London special.
How can digital twins boost profitability within construction?
The smart construction dashboard, as-built data and site changes forming an accurate digital twin.
Unlocking surplus public defence land and more to speed up the delivery of housing.
The Planning and Infrastructure Bill
An outline of the bill with a mix of reactions on potential impacts from IHBC, CIEEM, CIC, ACE and EIC.
Farnborough College Unveils its Half-house for Sustainable Construction Training.
Spring Statement 2025 with reactions from industry
Confirming previously announced funding, and welfare changes amid adjusted growth forecast.
Scottish Government responds to Grenfell report
As fund for unsafe cladding assessments is launched.
CLC and BSR process map for HRB approvals
One of the initial outputs of their weekly BSR meetings.
Architects Academy at an insulation manufacturing facility
Programme of technical engagement for aspiring designers.
Building Safety Levy technical consultation response
Details of the planned levy now due in 2026.
Great British Energy install solar on school and NHS sites
200 schools and 200 NHS sites to get solar systems, as first project of the newly formed government initiative.
600 million for 60,000 more skilled construction workers
Announced by Treasury ahead of the Spring Statement.
The restoration of the novelist’s birthplace in Eastwood.
Life Critical Fire Safety External Wall System LCFS EWS
Breaking down what is meant by this now often used term.
PAC report on the Remediation of Dangerous Cladding
Recommendations on workforce, transparency, support, insurance, funding, fraud and mismanagement.
New towns, expanded settlements and housing delivery
Modular inquiry asks if new towns and expanded settlements are an effective means of delivering housing.