Headed bars as a new anchorage method can be widely applied in high strength concrete structures because it solves some problems regarding highly congested joint, such as steel congestion and installation. However, the guideline of the headed bars on ACI 318-19 code is still based on the monotonic loading experiment and has not given more details about how to implement headed bars in building under seismic loading. Failure mode on the joint also need to be researched. Steel rebar yield (P/Py ≥1) failure is a more desirable final failure mode because it lets the headed bar able to develop its yield stress before the concrete start to fail instead of a sudden side-face blowout (SFB) failure (P/Py < 1).
This research mainly uses ANSYS to conduct monotonic and cyclic parametric studies. Before conducting the parametric study, remodeling from other researchers experiment and models is conducted to verify the ANSYS setting. Explicit Dynamic is used in monotonic loading FE analysis, while Static Structural is selected for the cyclic loading. This method selection is based on each specimens final failure mode. Based on the remodeling study, it is shown that ANSYS can produce a similar final load and failure pattern with the actual specimens. Finally, 144 monotonic FE models and 21 cyclic models are simulated.
The effects of the parameters from the monotonic loading study are then summarized to four engineering graphs as a guideline for engineers to achieve P/Py ≥1 when designing HSRC external beam-column joint using headed bars. The accuracy of the engineering graphs is then verified by plotting the cyclic FE parametric study to the graphs. Based on the result, it is shown that the graph can also be used to achieve P/Py ≥1 for specimen under cyclic loading. Additionally, it is shown that using ACI 318-19 seismic and headed bar requirement can achieve P/Py ≥1 for the main rebar and Mu > 1.25Mn for the beam.

Headed bars as a new anchorage method can be widely applied in high strength concrete structures because it solves some problems regarding highly congested joint, such as steel congestion and installation. However, the guideline of the headed bars on ACI 318-19 code is still based on the monotonic loading experiment and has not given more details about how to implement headed bars in building under seismic loading. Failure mode on the joint also need to be researched. Steel rebar yield (P/Py ≥1) failure is a more desirable final failure mode because it lets the headed bar able to develop its yield stress before the concrete start to fail instead of a sudden side-face blowout (SFB) failure (P/Py < 1).
This research mainly uses ANSYS to conduct monotonic and cyclic parametric studies. Before conducting the parametric study, remodeling from other researchers experiment and models is conducted to verify the ANSYS setting. Explicit Dynamic is used in monotonic loading FE analysis, while Static Structural is selected for the cyclic loading. This method selection is based on each specimens final failure mode. Based on the remodeling study, it is shown that ANSYS can produce a similar final load and failure pattern with the actual specimens. Finally, 144 monotonic FE models and 21 cyclic models are simulated.
The effects of the parameters from the monotonic loading study are then summarized to four engineering graphs as a guideline for engineers to achieve P/Py ≥1 when designing HSRC external beam-column joint using headed bars. The accuracy of the engineering graphs is then verified by plotting the cyclic FE parametric study to the graphs. Based on the result, it is shown that the graph can also be used to achieve P/Py ≥1 for specimen under cyclic loading. Additionally, it is shown that using ACI 318-19 seismic and headed bar requirement can achieve P/Py ≥1 for the main rebar and Mu > 1.25Mn for the beam.

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