Structurae

Load Bearing Capacity of Headed Studs in Case of Blow Out Failure Mode
Headed studs placed near to the edge of a concrete member can fail because of blow out. In case of this failure mode the concrete spalls at the lateral surface of the concrete member. The failure load can be calculated by the Concrete capacity method (CCmethod).
Numerical and experimental investigation show that the CC-method leads to conservative results. To determine the influence parameters on the load bearing capacity the tests of different authors are evaluated and advanced numerical simulations are carried out. The evaluation shows that
- the critical edge can be reduced to two times the edge distance.
- the influence of the edge distance is smaller than assumed.
- the influence of the concrete compressive strength is underestimated.
- the influence of headed stud placed sided by side is not considered. To get more economic results relating the load capacity of headed studs at the edge a modification of the CC-Method is proposed. This modified CC-method corresponds quite well with the test results as well as with the results of the numerical simulations. The proposed design equation will be included in the European design guide 'Design of Fasteners for Use in Concrete'.