scholarly journals A Numerical Study on Structural Performance of Railway Sleepers Using Ultra High-Performance Concrete (UHPC)

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2979
Author(s):  
Moochul Shin ◽  
Younghoon Bae ◽  
Sukhoon Pyo
Keyword(s):  
Cross Section ◽  
High Performance ◽  
High Performance Concrete ◽  
Numerical Study ◽  
Structural Performance ◽  
Geometrical Parameters ◽  
Ultra High Performance Concrete ◽  
Direct Tension ◽  
Design Factor ◽  
The Cross

This numerical study investigates the structural performance of railway sleepers made of ultra high-performance concrete (UHPC). First, numerical concrete sleepers are developed, and the tensile stress-strain relationship obtained from the direct tension test on the UHPC coupons is used for the tensile constitutive model after applying a fiber orientation reduction factor. The numerical sleeper models are validated with the experimental data in terms of the force and crack-width relationship. Second, using the developed models, a parametric study is performed to investigate the performance of the UHPC sleepers while considering various design/mechanical/geometrical parameters: steel fiber contents, size of the cross-section, and diameter and strength of prestressing (PS) tendons. The simulation results indicate that the size of the cross-section has the most impacts on the performance, while the effect of yielding strengths of PS tendons is minimal among all the parameters. Engineers need to pay attention to efficiency and an economical factor when using a larger cross-section, since sleepers with larger cross-sections can be an over-designed sleeper. This study suggests an economical design factor for engineers to evaluate what combination of parameters would be economical designs.

scholarly journals Investigate the Structural Response of Ultra High Performance Concrete Column under the High Explosion

2021 ◽  
Vol 71 (2) ◽  
pp. 256-264
Author(s):  
Viet-Chinh Mai ◽  
Xuan-Bach Luu ◽  
Cong-Binh Dao ◽  
Dinh-Viet Le
Keyword(s):  
Cross Section ◽  
High Performance ◽  
High Performance Concrete ◽  
Blast Resistance ◽  
Load Capacity ◽  
Structural Response ◽  
Blast Loading ◽  
Frame Structure ◽  
Ultra High Performance Concrete ◽  
Main Concept

Most of the structures that are damaged by an explosion are not initially designed to resist this kind of load. In the overall structure of any building, columns play an important role to prevent the collapse of frame structure under blast impact. Hence, the main concept in the blast resistance design of the structure is to improve the blast load capacity of the column. In this study, dynamic analysis and numerical model of Ultra High Performance Concrete (UHPC) column under high explosive load, is presented. Based on the Johnson Holmquist 2 damage model and the subroutine in the ABAQUS platform, a total of twenty UHPC model of the column were calculated. The objective of the article is to investigate the structural response of the UHPC column and locate the most vulnerable scenarios to propose necessary recommendations for the UHPC column in the blast loading resistance design. The input parameters, including the effect of various shapes of cross-section, scaled distance, steel reinforcement ratio, and cross-section area, are analyzed to clarify the dynamic behavior of the UHPC column subjected to blast loading. Details of the numerical data, and the discussion on the important obtained results, are also provided in this paper.

scholarly journals UHPC Infilled Circular steel Tube Column Design

2021 ◽  
Author(s):  
Youssef Hilal
Keyword(s):  
Cross Section ◽  
High Performance ◽  
High Performance Concrete ◽  
Steel Tube ◽  
Design Code ◽  
Ultra High Performance Concrete ◽  
Steel Tubes ◽  
Design Strength ◽  
Circular Steel Tube ◽  
Column Design

Previous researchers studied the behavior of Ultra-High Performance Concrete (UHPC) columns confined with steel tubes. However, predicting the influence of the confinement effect and the compressive capacity of these columns has yet to be further examined. Currently, the Canadian design code limits for reinforced concrete do not reach the strength nor the strain produced by using UHPC. This project uses the Canadian design methods for a cross-section of UHPC to form a column interaction curve and compared it with six test specimens. The effects of steel tube confinement will also be examined. Additionally, the Eurocode 4 (EC4) method, which includes the strengths of UHPC and confinement of steel tube, was used to formulate another column interaction curve. The results show that the Canadian code severely underestimates the design strength of confined UHPC while the EC4 provides much more accurate results.

Enhancing Resiliency and Delivery of Bridge Elements using Ultra-High Performance Concrete as Formwork

2019 ◽  
Vol 2673 (5) ◽  
pp. 443-453 ◽  
Author(s):  
Atorod Azizinamini ◽  
Sheharyar Rehmat ◽  
Amir Sadeghnejad
Keyword(s):  
Test Specimen ◽  
High Performance ◽  
High Performance Concrete ◽  
Numerical Study ◽  
Concrete Specimen ◽  
Point Load ◽  
Ultra High Performance Concrete ◽  
Normal Concrete ◽  
Element Analysis ◽  
Normal Strength

A feasibility study of the use of ultra-high performance concrete (UHPC) shell as a formwork is presented. The core concept of the research, developed by the first author, is prefabrication of UHPC shell which acts as a stay-in-place formwork. In the proposed approach, after transporting the UHPC shell to site, the construction of structural elements is completed by placing reinforcing cage inside the UHPC shell and post-pouring with normal concrete. The superior properties of UHPC provide excellent means to enhance the service life of bridge elements, while eliminating the need for assembling or stripping of formwork. As a proof of concept, a combination of experimental and numerical studies was conducted, results of which are reported here. Before conducting experimental work, numerical study in the form of finite element analysis was carried out to investigate performance of shell during placement of the normal concrete. To provide a baseline comparison between UHPC shell formwork and conventional methods, two test specimens were constructed and tested under three-point load setup. The shell test specimen demonstrated flexural strength, 14% greater than an equivalent normal strength concrete specimen. The UHPC shell test specimen failure occurred by debonding of shell at the interface and development of a large crack in the shell. The shell test specimen exhibited improved levels of ductility before failure. The preliminary analysis demonstrated that the idea is feasible and useful for accelerated bridge construction applications.

Ultra-High-Performance Concrete Shear Keys in Concrete Bridge Superstructures

2020 ◽  
pp. 036119812096472
Author(s):  
Elsy Y. Flores ◽  
Jordan Varbel ◽  
William K. Toledo ◽  
Craig M. Newtson ◽  
Brad D. Weldon
Keyword(s):  
High Performance ◽  
Load Transfer ◽  
Mechanical Performance ◽  
High Performance Concrete ◽  
Surface Preparation ◽  
Ultra High Performance Concrete ◽  
Direct Tension ◽  
Girder Bridges ◽  
Grouting Material ◽  
Shear Keys

This research investigated the use of locally produced, non-proprietary ultra-high-performance concrete (UHPC) as a grouting material to repair deteriorated shear keys. Shear keys are used in adjacent girder superstructures to produce monolithic behavior and load transfer across the structure. Shear key degradation can jeopardize the integrity of the structure. Transportation agencies have reported that 75% of distress in adjacent girder bridges is because of cracking and de-bonding along shear keys. Previous research has shown that locally produced UHPC has excellent mechanical and durability properties. UHPC has also been shown to have good bonding characteristics that are desirable in a potential grouting material. Bond strength between UHPC grout and substrate concrete was evaluated using slant-shear and direct tension tests. Results showed that adequate bond was achieved at 7 days. Low strengths at 28 days were observed because of low strength of the substrate concrete. Shrinkage of UHPC grout was also investigated. Shrinkage at 28 days was less than 600 µstrain which is acceptable for repair practices. Full-scale testing was used to evaluate load-deflection behavior of channel girder assemblages with grouted shear keys. Results showed that UHPC grout and non-shrink grout had similar mechanical performance. Excellent bond was achieved with all grouts, even with minimal surface preparation. The similar performances of the non-shrink grout and the UHPC grout indicates that UHPC grout does not provide a mechanical benefit over the non-shrink grout.

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