Non-Linear FE-Analysis of a Composite Action Girder with Coiled Spring Pins as Shear Connectors

Abstract: For bridges to cope with increased requirements such as increased loads, strengthening work can be carried out. In cases where older steel-concrete bridges do not have a composite action, an alternative is to create composite-action to achieve a higher flexural strength. It is introduced by post-installing shear connectors. There are many different alternatives of shear connectors that can be used, hence a number that can be installed from below the bridge to minimize the impact on the traffic. Coiled Spring Pins are of the interference fit type connector and are put in place from below the bridge by first drilling a hole upward through the upper steel flange and then into the concrete slab. Then, the spiral bolt is pushed up into the drilled hole by means of a hydraulic hammer. Using data from push-out tests and non-linear material models for steel and concrete, a non-linear finite element analysis was created using the commercial finite element software Abaqus. The analysis is based on dimensions and load cases that will mimic a planned full-scale beam test that will be carried out later in 2019. To verify that the material and the model behave in a realistic manner, an analysis was initially performed on a beam without composite-action, and a full-composite action beam with infinitely rigid connectors. These were then compared with hand calculations according to Eurocode. When the material models were verified, it is seen that the materials steel and concrete work for themselves in the analysis without composite-action and together in the analysis with full composite-action. The data for the spiral bolts is than defined instead of infinitely rigid connectors and new analyzes were performed to see the effect of the coiled spring pins properties. The results show that a significant increase in the point load in the middle of the beam can take place before failure occurs after installation of this type of shear connector. Already at a low number of connectors and a low shear connection-ratio, a significant increase in the flexural strength is seen in the beam. By using partial-composite action, with a lower number of spiral bolts, a significant higher flexural strength can be achieved in an economical way.