Projects / Programmes
Analysis of concentrated transfer of forces in bolted connections by means of ductility
| Code |
Science |
Field |
Subfield |
| 2.01.03 |
Engineering sciences and technologies |
Civil engineering |
Constructions in civil engineering |
| Code |
Science |
Field |
| T230 |
Technological sciences |
Building construction |
| Code |
Science |
Field |
| 2.01 |
Engineering and Technology |
Civil engineering |
steel structures, bolted connections, bolt bearing, ductility, numerical simulations
Researchers (1)
| no. |
Code |
Name and surname |
Research area |
Role |
Period |
No. of publicationsNo. of publications |
| 1. |
24336 |
PhD Primož Može |
Civil engineering |
Head |
2011 - 2013 |
238 |
Organisations (1)
Abstract
Bolted tensile splices are commonly used to connect constructional steel elements. The bolts act as a shear fasteners that transfer the load between steel elements. Thus, the bolt bearing represent concentrated transfer forces to steel plates. This results in stress concentration in the steel plate. If the material does not have sufficient ductility, the stress concentration causes fracture. Structural mild steel is ductile and provides the reduction of stress peaks. The bolt bearing resistance is defined in Eurocode. The resistance is based on the test results of the connections with one or two bolts. In the scientific literature, dealing with the tests of individual connections, indicates that the existing bolt bearing resistance is conservative and that the distribution of forces between several bolts is not given. The distribution is in some cases not uniform. The resistance also has a vague definition. It limits the bolt hole elongation, but the elongation is given as a stress limit. Professional international committee ECCS TC10 is also interested to find the solution to the problem.
In the framework of the project 50 bolted connections with a maximum of six bolts will be tested. The tests will be numerically simulated. Numerical parametric study will be performed on the basis of the verified numerical models. The geometry of the connection and the material will be the parameters in the study. The influence of connection geometry and the material on the connection resistance and on stress field will be analyzed. These results and the results of tests from the literature will be used to analyze the concentrated transfer of forces in bolted connections by means of ductility, the failure mechanisms, distribution of forces between the bolts and secondary effects resulting from the transfer of forces. The literature indicates that friction (secondary effect), which is caused by thickness deformation of the plate, plays an important role in the overall resistance, but has unfavourable effects on the bolts. The tension stress in combination with the shear stress reduces the resistance of the bolt. On the basis of the results new analytical method for the calculation of the bolt bearing resistance will be derived. Since the method will be based on failure mechanisms, it will be possible to determine the type of failure in the connection. The method will be statistically evaluated for its application in the engineering practice. Appropriate proposal for amendment of the relevant Eurocode will be addressed to proper authorities.
Significance for science
Significant results at the international level were achieved in the framework of this project. Concentrated transfer of forces in bolted connections by means of ductility was systematic analysed for mild steel grades as well as for high steel grades. The mechanism of the resistance was explained by numerical analysis. Furthermore, a new verification check for bearing resistance was developed. Its definition is based on extensive experimental testing and on the results of the numerical parametric studies. An original contribution of the project is also the evaluation of the bearing deformation capacity for steel grades up to S700. The bearing capacity is crucial for the redistribution of forces in the connection with several bolts. The model with equivalent springs for the calculation of the bearing stiffness was proposed. It provides excellent results for the connections with one or more bolts. The project results were presented to the international technical committees (ECCS TC 10, EvG 1993-1-12) in order to include the new knowledge (verification of the bearing resistance and net cross-section resistance) to standards EN 1993-1-1 and EN 1993-1-8. It is expected that the proposed amendments will get a general consensus, since the proposed solutions are simpler and less conservative than the existing.
Significance for the country
The results of the project will have a direct impact in Slovenia, taking into account the proposed amendments to standards EN 1993-1-1 and EN 1993-1-8. The Eurocode standards are also used in Slovenia. It is expected that the proposed amendments will get a general consensus, since the proposed solutions are simpler and less conservative than the existing. At the University of Ljubljana the knowledge obtained in this project will be included in the lectures dealing with steel structures. The knowledge is also disseminated to the designers through publications in Slovenian professional journals and elsewhere.
Most important scientific results
Annual report
2011,
2012,
final report,
complete report on dLib.si
Most important socioeconomically and culturally relevant results
Annual report
2011,
2012,
final report,
complete report on dLib.si
