Eliminating Column Formwork Using Prefabricated UHPC Shells: (Originally a subproject of “Envisioning Connection Detail for Connecting Concrete Filled Tube (CFT) Columns to Cap Beam for High Speed Rail Application”)

Link to Latest Report : September 2019 Progress Report

Background:
Traditional formwork acts as molds for wet concrete and supports concrete wet weight and live load of equipment and workers temporarily. Scaffolding acts as a supporting platform and provides temporary access to structures under construction. Erecting components of formworks and scaffolding together takes time, can cause traffic congestion, and increases the construction cost. It is also possible that the design cannot be incorporated due to unexpected site condition, and formwork failures can occur because of deviations from the original design. Formwork failure can also occur due to possible human errors or crushing of wooden surface where the heavy loads are placed if the bearing surface of joints is not appropriately designed. Based on “Use and Re-use of Formwork: Safety Risks and Reliability Assessment” report, the re-used formwork is not factored into its design, and since it is subjected to wide range of loads and exposures, it can experience possible degradation in its structural capacity. Furthermore, failure of formwork can also occur during concrete pours and can cause concrete leaking, failure of formwork components, complete structure collapse, and serious injuries or deaths. Possible failures of formwork can be caused by mistakes during erection, wrong calculations of weight acting on formwork, extra loads or due to natural disasters.

To prevent possible hazards of formwork and scaffolding failure, a new concept is proposed using ultra-high performance concrete (UHPC) to prefabricate a shell which acts as permanent stay-in-place form for bridge elements. The prefabricated shell is intended to eliminate the conventional formwork and scaffolding while reducing the on-site construction time and acting as a durable protective layer for normal strength concrete inside it.

Objective:

The main objectives of this project are:

1- The development of prefabricated UHPC shell for bridge column.

3- The development of column-to-footing and column-to-cap beam connections for the proposed column with UHPC shell.

4- Conducting an experimental study on the proposed bridge column utilizing UHPC shell under constant axial and lateral cycle loads

5- Conducting numerical modeling using finite element models on the tested specimen.

Scope:

An overview of the study tasks is given below.

Task 1 – Design and analysis of the column specimens
In this task, the first column will be designed and analyzed using smooth surface between UHPC shell and normal strength concrete inside for the first specimen and shared longitudinal reinforcement between UHPC shell and normal strength concrete inside for the second specimen. Also, the connection between the column and footing will be studied using UHPC to reduce lap splice length between column longitudinal reinforcement and footing dowels.

Task 2– Construction of the first specimen
In this task, the construction of the first specimen will be conducted. A construction procedure will be proposed for field implementation.

Task 3– Experimental work for the first specimen
In this task, experimental work will be conducted on the first specimen. The column will be tested under constant axial and lateral cyclic loads. Figure 2 show the test setup.

Task 4– Construction of the second specimen
Based on the results from Task 2 and Task 3, the design and analysis of the second column will be refined then the construction of the second specimen will be conducted.

Task 5 – Experimental work for the second specimen
In this task, experimental work will be conducted on the second specimen. The column will be tested under constant axial and lateral cyclic loads.

Task 6 – Final Report
In this Task, Full assessment of the findings from Task 1 throughout Task 5 will be conducted and a report will be published including design recommendations for the prefabricated UHPC shells.

Research Team:

Principal Investigator: Dr. Atorod Azizinamini
Co-Principal Investigator: Dr. Islam Mantawy
Research Assistant: Nerma Caluk

Summary
The proposed research suggests experimental testing and finite element modeling for bridge columns with prefabricate a shell which acts as permanent stay-in-place form for bridge elements. The prefabricated shell is intended to eliminate the conventional formwork and scaffolding while reducing the on-site construction time and acting as a durable protective layer for normal strength concrete inside it.