| Author: | Zhu, Jixiang |
| Title: | Structural behavior of prefabricated UHPC-Steel-ECC hybrid box culvert |
| Advisors: | Dai, Jian-guo (CEE) |
| Degree: | M.Sc. |
| Year: | 2019 |
| Subject: | Concrete construction High strength concrete Hong Kong Polytechnic University -- Dissertations |
| Department: | Department of Civil and Environmental Engineering |
| Pages: | ix, 91 pages : color illustrations |
| Language: | English |
| Abstract: | Precast concrete has become the main construction method for underground utility tunnel in domestic cities. The prefabricated utility tunnel has excellent performance on structure safety, strong corrosion resistance and long service life. Ultra-high-performance concrete (UHPC) is a concrete material with both high strength and high durability. High toughness concrete, also known as ECC (Engineered Cementitious Composite), is a concrete material characterized by tensile strain hardening behavior and multiple cracking designed by micromechanical principles, and its tensile strain capacity is 3%~8%, which is 300~800 times that of normal concrete. Thus, this paper proposes a novel underground utility tunnel concrete structure system by using a combination of perforated steel plates and the above two types of concrete to develop a new type of prefabricated construction for underground buildings. The green ultra-high-performance concrete with different functions are used as the internal fireproof and external durability protection materials and the perforated steel plate are used to achieve a composite action between these materials. The main objective of the research is to explore the structural performance of this UHPC-Steel-ECC hybrid utility tunnel. Firstly, the prefabrication method of this novel utility tunnel has been designed. To simulate the real structural behavior of the composite box culvert, the testing of a single barrel utility tunnel has been designed. The details of loading method and measuring system have been presented in this paper. It should be mentioned that the DIC technique was also used to ensure the accuracy of data acquisition. The test results show that the test specimen has experienced three stages of cracking, stiffness degradation and ultimate damage. The failure mode of the specimen is characterized by the shear crack near the bending zone of the top floor; when the load reaches the design load value, the deflection does not exceed the limit and excellently meet the requirements of the code and the ultimate capacity of the specimen reaches twice the design load value. To better understand the composite action between the concrete and steel plate, the composite coupon samples are designed. Samples of ECC-steel, UHPC-steel composites and perforated steel plates of different cutout were investigated. The test result shows that all the composite samples exhibits apparent improvement at the strength and ductility. The tensile capacity of ECC composites reach about 2% and the strength of UHPC composites increase to 6 MPa. Besides, the regular and rational crack patterns have also been observed through Digital Image Correlation technique. |
| Rights: | All rights reserved |
| Access: | restricted access |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| 5288.pdf | For All Users (off-campus access for PolyU Staff & Students only) | 4.55 MB | Adobe PDF | View/Open |
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