scholarly journals Penetration modeling of ultra‐high performance concrete using multiscale meshfree methods

2021 ◽  
Author(s):  
Paul Sparks ◽  
Jesse Sherburn ◽  
William Heard ◽  
Brett Williams
Keyword(s):  
High Performance ◽  
Reproducing Kernel ◽  
High Performance Concrete ◽  
Numerical Models ◽  
Damage Model ◽  
Particle Method ◽  
Reproducing Kernel Particle Method ◽  
Ultra High Performance Concrete ◽  
Meshfree Analysis ◽  
Protective Structures

Terminal ballistics of concrete is of extreme importance to the military and civil communities. Over the past few decades, ultra‐high performance concrete (UHPC) has been developed for various applications in the design of protective structures because UHPC has an enhanced ballistic resistance over conventional strength concrete. Developing predictive numerical models of UHPC subjected to penetration is critical in understanding the material's enhanced performance. This study employs the advanced fundamental concrete (AFC) model, and it runs inside the reproducing kernel particle method (RKPM)‐based code known as the nonlinear meshfree analysis program (NMAP). NMAP is advantageous for modeling impact and penetration problems that exhibit extreme deformation and material fragmentation. A comprehensive experimental study was conducted to characterize the UHPC. The investigation consisted of fracture toughness testing, the utilization of nondestructive microcomputed tomography analysis, and projectile penetration shots on the UHPC targets. To improve the accuracy of the model, a new scaled damage evolution law (SDEL) is employed within the microcrack informed damage model. During the homogenized macroscopic calculation, the corresponding microscopic cell needs to be dimensionally equivalent to the mesh dimension when the partial differential equation becomes ill posed and strain softening ensues. Results of numerical investigations will be compared with results of penetration experiments.

Design and evaluation of a wedge-type anchor for fibre reinforced polymer tendons

2000 ◽  
Vol 27 (5) ◽  
pp. 985-992 ◽  
Author(s):  
T I Campbell ◽  
N G Shrive ◽  
K A Soudki ◽  
A Al-Mayah ◽  
J P Keatley ◽  
...  
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Numerical Models ◽  
Ultra High Performance Concrete ◽  
Reinforced Polymer ◽  
Anchorage System ◽  
Fibre Reinforced Polymer ◽  
Load Tests ◽  
Tendon Tension ◽  
Post Tensioning

The development of a wedge-type anchorage system for fibre reinforced polymer (FRP) tendons, as part of an overall corrosion-free post-tensioning system, is outlined in this paper. A stainless steel anchor is described, and results from numerical models and load tests to evaluate its behaviour under loads from anchor set, as well as static and repeated tendon tension, are presented. An alternative wedge-type anchorage system made from ultra-high performance concrete is also described. It is shown that, although significant progress has been made in development of the anchorage, further work is required to make it more robust.Key words: FRP tendons, post-tensioning, anchorage, corrosion-free, mathematical models, load tests, concrete.

scholarly journals Laboratory characterization of Cor-Tuf Baseline and UHPC-S

2021 ◽  
Author(s):  
Dylan Scott ◽  
Steven Graham ◽  
Bradford Songer ◽  
Brian Green ◽  
Michael Grotke ◽  
...  
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
The United States ◽  
Design Guidelines ◽  
Ultra High Performance Concrete ◽  
Laboratory Characterization ◽  
Potential Benefits ◽  
The Republic ◽  
Protective Structures

This experimental effort is part of a larger program entitled Development of Ultra-High-Performance Concrete Tools and Design Guidelines. This program operates in accordance with an agreement concerning combating terrorism research and development between the United States of America Department of Defense and the Republic of Singapore Ministry of Defence. The objective of the program is to develop a better understanding of the potential benefits that may be achieved from the application of ultra-high-performance concrete (UHPC) materials for protective structures. The specific effort detailed in this report will provide insight into laboratory-scale mechanical properties of Cor-Tuf and a proprietary material termed UHPC-Singapore (UHPC-S).

Fracture-Mechanical Parameters for Modeling of Quasi-Brittle Materials and Structures

2015 ◽  
Vol 1106 ◽  
pp. 106-109
Author(s):  
Radomír Pukl ◽  
Tereza Sajdlová ◽  
Drahomír Novák ◽  
David Lehký
Keyword(s):  
Inverse Analysis ◽  
High Performance ◽  
High Performance Concrete ◽  
Numerical Models ◽  
Brittle Materials ◽  
Cementitious Materials ◽  
Mechanical Parameters ◽  
Ultra High Performance Concrete ◽  
Open Questions ◽  
Fracture Mechanical Parameters

The scatter of experimental results using specimens made of quasi-brittle materials, such as concrete, fibre-reinforced concrete, ultra high performance concrete etc., can be due to their heterogeneity rather high. An assessment of fracture-mechanical parameters is then difficult and problematic. To remain at deterministic level is therefore unrealistic and without virtual statistical approach, simulation and probabilistic result assessment the consequent practical design of quasi-brittle material-based structures can be risky. A key parameter of nonlinear fracture mechanics modeling is fracture energy of concrete. Numerical simulation of concrete failure and fracture phenomena in concrete as well as other cementitious materials became a field of an intensive research in the recent years. With respect to accuracy and efficiency of corresponding numerical models some few still open questions have to be focused. How the heterogeneity of cementitious materials can be taken into consideration in the most realistic way using commercially available finite element programs? A sophisticated option to get the parameters of the computational model indirectly is based on combination of fracture test with inverse analysis. This paper describes a methodology to get such parameters using experimental data from three-point bending tests used in inverse analysis based on combination of artificial neural networks and stochastic analysis.

Flexural design of precast, prestressed ultra-high-performance concrete members

PCI Journal ◽  
2020 ◽  
Vol 65 (6) ◽  
pp. 35-61
Author(s):  
Chungwook Sim ◽  
Maher Tadros ◽  
David Gee ◽  
Micheal Asaad
Keyword(s):  
Prestressed Concrete ◽  
High Performance ◽  
High Performance Concrete ◽  
Limit State ◽  
Design Guidelines ◽  
Design Tool ◽  
Supplementary Cementitious Materials ◽  
Ultra High Performance Concrete ◽  
Concrete Members ◽  
Cylinder Strength

Ultra-high-performance concrete (UHPC) is a special concrete mixture with outstanding mechanical and durability characteristics. It is a mixture of portland cement, supplementary cementitious materials, sand, and high-strength, high-aspect-ratio microfibers. In this paper, the authors propose flexural design guidelines for precast, prestressed concrete members made with concrete mixtures developed by precasters to meet minimum specific characteristics qualifying it to be called PCI-UHPC. Minimum specified cylinder strength is 10 ksi (69 MPa) at prestress release and 18 ksi (124 MPa) at the time the member is placed in service, typically 28 days. Minimum flexural cracking and tensile strengths of 1.5 and 2 ksi (10 and 14 MPa), respectively, according to ASTM C1609 testing specifications are required. In addition, strain-hardening and ductility requirements are specified. Tensile properties are shown to be more important for structural optimization than cylinder strength. Both building and bridge products are considered because the paper is focused on capacity rather than demand. Both service limit state and strength limit state are covered. When the contribution of fibers to capacity should be included and when they may be ignored is shown. It is further shown that the traditional equivalent rectangular stress block in compression can still be used to produce satisfactory results in prestressed concrete members. A spreadsheet workbook is offered online as a design tool. It is valid for multilayers of concrete of different strengths, rows of reinforcing bars of different grades, and prestressing strands. It produces moment-curvature diagrams and flexural capacity at ultimate strain. A fully worked-out example of a 250 ft (76.2 m) span decked I-beam of optimized shape is given.

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