Volume 4. No. 1
Special section: High-Performance Fiber Reinforced Cementitious Composites edited by Dr. S. Ohno

Tensile Characteristics Evaluation Method for Ductile Fiber-Reinforced Cementitious Composites (Invied Paper)
Toshiyuki Kanakubo
Journal of Advanced Concrete Technology, 4(1) 3-17, 2006

In this paper, tensile test methods for concrete and cementitious composites are shortly summarized. Comparisons of uniaxial tensile test results of round robin test, which was conducted as one of the activities of Japan Concrete Institute Technical Committee for DFRCC, are introduced. Four types of tensile test methods for four types of DFRCC were performed in this round robin test. There are differences of obtained results by testing methods and compacting direction of DFRCC. The relationships between tensile test results and tensile characteristics calculated from bending test results are discussed. The Japan Concrete Institute standard for test method by 4-point bending test is introduced. The standard is based on the activities of JCI Technical Committee and results of round robin test. It is considered that the standard indicates one example of evaluation method of DFRCC tensile characteristics.

Recent Progress on HPFRCC in Japan- Required Performance and Applications - (Invied Paper)
Minoru Kunieda and Keitetsu Rokugo
Journal of Advanced Concrete Technology,4(1) 19-33, 2006

High Performance Fiber Reinforced Cement Composites (HPFRCC) show multiple cracking and strain-hardening behaviors in tension. Current applications in Japan include bridge decks, building dampers, retaining wall, irrigation channels and so forth. While the novel properties of HPFRCC are well known, the required performance and its criteria have not been clarified. For example, in addition to tensile load bearing capacity, protection against penetration of substance through fine cracks is also important. Clarification of the required performance and its criteria for HPFRCC is important to evaluate the design concepts of each application. This paper introduces recent applications using HPFRCC in Japan, focusing on required performance.

Application of High Performance Fiber Reinforced Cementitious Composites for Damage Mitigation of Building Structures- Case study on Damage Mitigation of RC Buildings with Soft First Story -
Hiroshi Fukuyama
Journal of Advanced Concrete Technology, 4(1) 35-44, 2006

It is essential to introduce the performance-based design system and develop the new technology for meeting the social requirements to building structures. This paper introduces the need of the damage mitigation of building structures under the performance-based design.For this purpose, the High Performance Fiber Reinforced Cement composite (HPFRCC) device which has high strength, stiffness and ductility is introduced. Analytical study on seismic response of the soft- first story building with and without the HPFRCC devices was performed to investigate the feasibility of proposed technique for damage mitigation against large earthquake. The results indicate that the HPFRCC device can reduce the drift angle of the soft-first story from 2% to 0.5% in case of seismic input normalized 50 cm/sec in maximum velocity. Since drift angle of 0.5% means elastic response of the structure, it is confirmed the proposed technique has much potential as a new structural technology for damage mitigation.

Nonlinear Finite Element Analysis on Shear Failure of Structural Elements Using High Performance Fiber Reinforced Cement Composite
Haruhiko Suwada and Hiroshi Fukuyama
Journal of Advanced Concrete Technology, 4(1) 45-57, 2006

High performance fiber reinforced cement composites (HPFRCC) are highly ductile and are characterized by pseudo strain hardening in tension. It is expected to achieve a high level in structural performance by applying the HPFRCC. However, there are many uncertainties on the influence of the tensile characteristic of HPFRCC to the shear resistance mechanism of structural element applying HPFRCC. Though FEM analysis is an effective engineering tool to analyze the relationship between the materials characteristic and the structure performance of the elements, a robust constitutive model is indispensable for obtaining accurate results. This paper proposes constitutive models based on the basic test results. The proprieties of the model are confirmed based on the comparison between the analytical simulation and the structural test results on the behavior of shear failure. The analytical results using proposed model correspond reasonably well with the experimental results of the HPFRCC structural element.

Practical Design Criteria for Saturated Pseudo Strain Hardening Behavior in ECC
Tetsushi Kanda and Victor C. Li
Journal of Advanced Concrete Technology, 4(1) 59-72, 2006

Engineered Cementitious Composites (ECCs) have recently demonstrated their high performance with pseudo strain hardening (PSH) behavior in civil engineering structures and buildings. These ECCs incorporate low cost fibers like Polyvinyl Alcohol fibers which often involve fiber rupture in composites. Such fiber rupture type ECCs tend to have inferior and unsaturated PSH behavior compared with properly designed pull-out type. The present study focused on presenting practical criteria to achieve designing saturated PSH behavior in fiber rupture type ECCs. These criteria were proposed based on two performance indices, which are measures of energy exchange during steady state flat crack propagation and stress level to initiate micro-cracks. The latter performance index necessitated a new cracking strength prediction theory, which was proposed in the current study. Finally the cracking strength theory was justified using tensile test data, and the criteria were proposed based on the data in terms of these two indices.

Method of test for bending moment-curvature curve of fiber-reinforced cementitious composites
JCI TEchnical Committee
Journal of Advanced Concrete Technology, 4(1) 73-78, 2006

Effects of Strain Rate on Tensile Behavior of Reactive Powder Concrete
Kazunori Fujikake, Takanori Senga, Nobuhito Ueda, Tomonori Ohno and Makoto Katagiri
Journal of Advanced Concrete Technology, 4(1) 79-84, 2006

Reactive Powder Concrete (RPC) reinforced with short steel fibers is characterized by an ultra-high strength and high fracture toughness. Because of its excellent property, RPC may be suitable as an advanced material for reinforced concrete structures subjected to impact loading. Thus, the objective of this study was to find out dynamic tensile behaviors of RPC specimens subjected to rapid loadings. The influence of the loading rates on failure modes, tensile stress-elongation curves and tensile stress-crack opening curves was investigated. Furthermore, based on the test results, a dynamic bridging law expressing the relation between tensile stress and crack opening was proposed.

Nonlinear Analysis for Reactive Powder Concrete Beams under Rapid Flexural Loadings
Kazunori Fujikake, Takanori Senga, Nobuhito Ueda, Tomonori Ohno and Makoto Katagiri
Journal of Advanced Concrete Technology, 4(1) 85-97, 2006

The aim of this study was to develop an analytical model based on a fiber model technique for representing the behavior of a reinforced Reactive Powder Concrete (RPC) beam subjected to rapid flexural loads. In the analytical model, first, the moment-curvature relationship of the section of the RPC beam was calculated,
considering the fact that the constituent materials, i.e., RPC and reinforcing steel, exhibited the strain rate effects on the mechanical properties. Then, the load-midspan deflection relationship was obtained through the moment-curvature relationship. The analytical model was applied to the experimental results for verification. The analytica l results were in good agreement with the experimental results. Subsequently, the analytical investigations were performed for finding out the influence of variables, such as loading rates, compressive strengths, the amount of reinforcing steel and the volume fraction of steel fibers, on the behaviors of RPC beams.

Study on Impact Response of Reactive Powder Concrete Beam and Its Analytical Model
Kazunori Fujikake, Takanori Senga, Nobuhito Ueda, Tomonori Ohno and Makoto Katagiri
Journal of Advanced Concrete Technology, 4(1) 99-108, 2006

The aim of this study was to experimentally examine the impact response of a RPC (Reactive Powder Concrete) beam and to develop an analytical model to represent its impact response as well. Thus, a drop hammer impact test was performed for investigating the influence of the drop height of a hammer on the impact response of a RPC beam. Subsequently, a static flexural loading test was conducted for finding out the residual loading capacity of the RPC beam damaged in the impact test. In the impact analysis, the two degrees of freedom mass-spring-damper system model was proposed. The analytical results were in good agreement with the experimental results. However, the considerable degree of damping for the local response at a contact point was required in the impact analysis.

Compressive Stress-Strain Behavior of Small Scale Steel Fibre Reinforced High Strength Concrete Cylinders
Pradeep Bhargava, Umesh K.Sharma and Surendra K. Kaushik
Journal of Advanced Concrete Technology, 4(1) 109-121, 2006

An experimental investigation was carried out to generate the complete stress-strain curves of steel fibre reinforced high strength concrete under axial compression. The experimental program consisted of testing 100 x 200 mm concrete cylinders. The experimental variables of the study were concrete strength levels (58.03 MPa and 76.80 MPa), volume fractions (0.5% to 2.0%) and aspect ratios (20 and 40) of flat crimped steel fibres. The effect of mixed aspect ratio of fibres on the stress-strain behavior of steel fibre high strength concrete was also studied by blending the short and long fibres. The effects of these variables on the stress-strain curves are presented and discussed. Based on the test data obtained, a simple model is proposed to generate the complete stress-strain relationship for steel fibre reinforced high strength concrete. The proposed model has been found to give a good representation of the actual stress-strain response.

Shear Strength of Fiber Reinforced Reactive Powder Concrete Prestressed Girders without Stirrups
Yen Lei Voo, Stephen J. Foster and R. Ian Gilbert
Journal of Advanced Concrete Technology, 4(1) 123-132, 2006

Experimental results from tests on seven 650 mm deep large-scale reactive powder concrete (RPC) I-section girders failing in shear are reported herein. The girders were cast using 150 170 MPa steel fiber RPC and were designed to assess the capacity to carry shear stresses in thin webbed prestressed beams without shear reinforcement. The tests showed that the quantity and types of fibers in the concrete mix did not significantly affect the initial shear cracking load but increasing the volume of fibers increased the failure load. A design model is developed to calculate the strength of the RPC beams tested in this study. The model, based on the crack-sliding model, uses plasticity theory combined with observations from the variable engagement model for mode I failure of fiber reinforced concrete. The results of the model are compared with test data and show a good correlation.

Unified Analytical Approaches for Determining Shear Bond Characteristics of FRP-Concrete Interfaces through Pullout Tests
Jianguo Dai, Tamon Ueda and Yasuhiko Sato
Journal of Advanced Concrete Technology, 4(1) 133-145, 2006

Pullout test is a conventional test method for calibrating interfacial shear bond characteristics of FRP-concrete interfaces. However, due to small bending stiffness of FRP sheets/strips and highly non-linear interface fracturing manners, extensive studies up to now have not yet led to a well-recognized analytical approach to interpret accurately the pullout test results particularly when the aim is to calibrate a local bond stress-slip model, which is necessary as well for developing bond strength and anchorage length models through a general way by avoiding use of empirical formulation. This paper employs a newly developed non-linear bond stress-slip model for analyzing full-range strain distributions in FRP and shear bond stress distributions in the interface bond layer during a pullout test. As a consequence, new anchorage length and bond strength models are developed.

Time-Dependent Structural Analysis Considering Mass Transfer to Evaluate Deterioration Process of RC Structures
Hikaru Nakamura, Worapong Srisoros, Ryosuke Yashiro and Minoru Kunieda
Journal of Advanced Concrete Technology, 4(1) 147-158, 2006

The time dependent structural analysis method under multi actions in consideration of drying shrinkage due to moisture transfer and re-bar corrosion due to chloride ion penetration as well as external load actions was developed. The Rigid-Body-Spring Networks (RBSN) and truss networks model were used for structural analysis and mass transfer analysis, respectively. In addition to, mass transfer through bulk concrete, the one through cracks by setting truss networks on the boundaries of Voronoi particle was also considered. It was confirmed that the developed method was well simulated the deterioration process due to mass transfer for initial cracking behavior and ultimate behavior of concrete structures.

Direct Path-Integral Scheme for Fatigue Simulation of Reinforced Concrete in Shear
Koichi Maekawa, Kukrit Toongoenthong, Esayas Gebreyouhannes and Toshiharu Kishi
Journal of Advanced Concrete Technology, 4(1)159-177, 2006

Path-dependent fatigue constitutive models for concrete tension, compression and rough crack shear are proposed and directly integrated with respect to time and deformational paths actualized in structural concrete. This approach is experimentally verified to be consistent with the fatigue life of materials and structural members under high repetition of forces. The mechanistic background of the extended truss model for fatigue design is also investigated. The coupling of fatigue loads with initial defects is simulated and its applicability is discussed as a versatile tool of performance assessment.

Cross-Sectional Damage Index for RC Beam-Column Members Subjected to Multi-Axial Flexure
Satoshi Tsuchiya and Koichi Maekawa
Journal of Advanced Concrete Technology, 4(1) 179-192, 2006

A damage index for seismic performance of RC members is proposed on the basis of 3D multi-axial fiber analysis. The elasto-plastic and fracturing model for concrete compression is applied for estimation of the fracture parameter, which is defined as the reduced elastic stiffness for each micro-cell component of member cross sections. The averaged fracture parameter over the cross section is treated as the index of cross-sectional damage for remaining axial force-carrying mechanism. This index provides an approximation of damage related to seismic performance level II (reparable after seismic actions) not only for one-directional but also multi-axial flexure. This method is also effective for RC members confined by lateral ties.

Time-Dependent Space-Averaged Constitutive Modeling of Cracked Reinforced Concrete Subjected to Shrinkage and Sustained Loads
Koichi Maekawa, Masoud Soltani, Tetsuya Ishida and Yutaka Itoyama
Journal of Advanced Concrete Technology, 4(1) 193-207, 2006

Transient nonlinear analysis is proposed as a way of predicting the long-term deformation of cracked reinforced concrete and a mechanistic creep constitutive model for post-cracking tension-stiffness is presented. The effect of drying shrinkage is integrated into the predictive scheme using the thermo-hydro physics of porous media, and a simple equivalent method of analysis is discussed for the practical performance assessment of structural concrete. Careful verification of the model is carried out with respect to the creep deflection of RC beams and slabs subjected to multi-axial flexure. Three-dimensional fiber and plate & shell elements are used for the space discretization of the analysis domain.