Load‐bearing behaviour of high‐strength bolts in combined tension and shear

Abstract

Bolts were tested under different combinations of tension and shear in order to estimate how bolts generally behave in combined tension and shear, what influence the strength grade has and to be able to assess the validity of the old and new standard rules. To assure results that not only represent the behaviour of round steel, but of a bolt as such, a test setup was developed that ensured a construction situation as realistic as possible. The results of these tests are summarized in this paper.

Tests on 10.9 Bolts Under Combined Tension and Shear During and After Fire

“…All tests were conducted at ambient temperature. The results of the bolts tested with the prototype of the new test rig (Figure5) do not totally match the results from Renner (Renner et al 2012). This is mainly explained by the more rigid construction of the new test rig, where the displacements in horizontal direction are constrained by the friction between the testing rig and the compression machine.…”

“…For this test series M20 shank bolts of the property class 10.9 were heated to 500°C, 700°C, 800°C and 900°C and then slowly cooled to ambient temperature. Test rigs were used that were designed for a large experimental study on the interaction behaviour of bolts of different property classes at ambient temperature (Renner et al 2012).With each of the three test rigs a bolt can be pulled in two different angles, each causing a different tension-to-shear relation. In Figure 2 the test rig for the angles 45° and 0° is shown.…”

“…For the planned tests at elevated temperatures the test rigsdesigned by (Renner et al 2012) are not practical, due to the boundary conditions of the furnace which is needed. However, the basic idea of applying load in only one direction but thereby straining the bolt both by tension (in the bolt axis) and shear (perpendicular to the bolt axis) through a suitable test rig at the same time should be retained.…”

“…New test rigs that are based on this basic idea where designed, while at the same time taking into account that the furnace that is to be used for the tests only allows application of pressure. The design combines the principles of a compact test rig by (Godley et al 1982), where tension tests in bolts were done by applying compression, and the use of different angles as in the tests rigs by (Renner et al 2012). In Figure 4 the newly designed test rigs for an angle of 0° (left), 30° (centre) and 45° (right) are shown.…”

“…First a prototype with an angle of 45° (Figure4, right) was built out of S355 construction steel to verifywhether it functions as predicted. The same bolts that were tested by Renner (Renner et al 2012) were used in order to have a direct comparison of the test results. All tests were conducted at ambient temperature.…”