Volume 5, No. 2 High-Strengrth and High-Performance Concrete edited by Prof. M. Nishiyama Study of New RC Structures Using Ultra-High-Strength Fiber-Reinforced Concrete (UFC)-The Challenge of Applying 200 MPa UFC to Earthquake Resistant Building Structures (Invited paper) Shunsuke Sugano, Hideki Kimura and Kazuyoshi Shirai Journal of Advanced Concrete Technology, 5(2) 133-147, 2007 This paper describes the seismic behavior of new reinforced concrete (RC) building structures using ultra-high-strength fiber-reinforced concrete (UFC) with 200 MPa strength. A series of tests of columns and frames in UFC buildings subjected to seismic forces were conducted to obtain basic data of their behavior and to provide guides for design and construction. The test results are summarized as follows. 1) UFC, which is basically a brittle material, could be well confined with high-strength lateral reinforcements. 2) Stable behavior of columns could be obtained even under very high axial compression when they were well confined with high-strength lateral reinforcements. 3) Steel-fibers in UFC significantly enhanced the shear resistance of columns and frames. Analytical investigations indicated that the shear behavior of a column and a frame can be well evaluated by considering the contribution of steel fibers to the tensile resistance of UFC. Serviceability Performance Evaluation of RC Flexural Members Improved by Using Low Shrinkage-High Strength Concrete Makoto Tanimura, Ryoichi Sato and Yoichi Hiramatsu Journal of Advanced Concrete Technology, 5(2) 149-160, 2007 This paper focuses to show the importance of autogenous shrinkage on serviceability performance of reinforced high-strength concrete (HSC) flexural beams, and also the effectiveness of low-shrinkage HSCs (LS-HSC) that made by using expansive additive and/or shrinkage-reducing chemical agent and/or Belite-rich low heat Portland cement with regards to the improvement of flexural serviceability performances of the beams. In addition, this paper, from the design equation point of view, proposes a new concept for evaluating flexural crack width and deformation of RC beams, considering the early age deformation of concrete before loading. The experimental results show that autogenous shrinkage of HSC affect the increase in crack width and deformation of the RC beams significantly, while LS-HSCs markedly improve its serviceability performances. The present concept, taking into account strain change in tension reinforcement and curvature change at cracked section before and after loading, is effective in explaining the effects of shrinkage and expansion of concrete before loading on maximum crack width and flexural deformation of the RC beams. JSCE (Japan Society of Civil Engineers) code equations for predicting maximum crack width and flexural deformation into which the present concept is incorporated, improve the prediction accuracy compared with conventinal ones and show fairly good agreement with experimental results.. Adiabatic Curing Method for Estimating 91-day Strength in Structure with 150 MPa Concrete Hiroshi Jinnai, Shusuke Kuroiwa, Satoshi Watanabe and Satoru Namiki Journal of Advanced Concrete Technology, 5(2) 161-170, 2007 The specimens cured by several simple adiabatic tanks were examined for the quality control of strength in structure of 150MPa concrete. It has been understood that the tank where 2 by 5 specimens are arranged is good as a result of the experiment. Then, it was used for the quality control of actual building operations. As a result, specimen cured by selected tank was able to administrate the strength in structure of 150MPa concretes appropriately. Moreover, quality control results of 150MPa concrete were excellent. Performance Confirmation Tests on C100 Concrete in Dubai, UAE Shusuke Kuroiwa, Yoshitaka Inoue, Kensuke Fujioka and Adel William Journal of Advanced Concrete Technology, 5(2) 171-180, 2007 Numerous skyscrapers have been being built by reinforced concrete construction in Dubai, UAE. Because the use of high strength concrete is advantageous for skyscrapers from a number of aspects, concrete with a 100 N/mm2 level compressive strength was produced using materials locally available, with its properties while fresh and after hardening being investigated. Its placing performance in a mock-up column and in-situ strength development were also examined to investigate its applicability to actual construction. As a result, it was confirmed that the properties of fresh concrete were retained with little changes over the required period, and the mechanical and durability properties of hardened concrete were good. Mock-up testing also revealed that the placeability of the concrete was sufficiently good, and the compressive strength and elastic modulus of cores drilled from the mock-up were proven to be satisfactory as a concrete of a compressive strength level of 100 N/mm2. Structural Design of 80-Story RC High-Rise Building Using 200 MPa Ultra-High Strength Concrete Hideki Kimura, Tadao Ueda, Kazuo Otake and Astushi Kanbayashi Journal of Advanced Concrete Technology,5(2) 181-191, 2007 This paper presents a trial design of an 80-story RC high-rise building using ultra high strength concrete. Static nonlinear push over analysis and Level-1 and Level-2 for non-linear earthquake response analyses and non-linear wind response analyses are carried out. Responses of the building satisfied all design criteria. Seismic Behavior of 200 MPa Ultra-high Strength Steel-Fiber Reinforced Concrete Columns under Varying Axial Load Hideki Kimura, Yuji Ishikawa, Atsushi Kanbayashi and Hirohito Takatsu Journal of Advanced Concrete Technology, 5(2) 193-200, 2007 Bending-shear tests were carried out on ultra-high strength RC columns under high axial load conditions. Effective compression strength of concrete attained 200 MPa by adding ultra-high strength steel fibers (SF). The investigated parameters are: 1) steel fiber ratio, 2) lateral reinforcement ratio, and 3) axial loading type. Main characteristics of tested columns (Maximum strengths, deformation limits and equivalent viscous damping factors) are presented and influence of different parameters is discussed. Test results revealed the advantage of using SF in terms of strength and deformability. Maximum strength of tested columns assessed by different formula considering the confinement effect of concrete, when SF is used, proved to be on the safe side due to cross-section reduction. Therefore, when SF is not added, estimation of maximum strength proved to be possible using NZS3101 equation based on flexural analysis and cross-section reduction. Study on Leaching of Hexavalent Chromium from Hardened Concretes Using Tank Leaching Test Shigeru Takahashi, Etsuo Sakai and Takafumi Sugiyama Journal of Advanced Concrete Technology, 5(2) 201-207, 2007 The tank leaching test has been carried out for investigating the behavior of leaching trace elements from monolith sample. This study investigated the behavior of the leaching of hexavalent chromium from mortar or concrete by tank leaching test. The amount of leached hexavalent chromium for a day didn't depend on Leachant/Surface area ratio and increased with the amount of work water. When the concretes were cured at sealing, the hexavalent chromium hardly leached. But, when the concretes was dried in the room, the amount of leaching of hexavalent chromium became large. The leaching of hexavalent chromium from using concrete were evaluated from these results. In the case which the continuous water works against concrete, such as the piers of bridges which were built over rivers or lakes, the leaching of hexavalent chromium hardly affected the environment for water. When it rains, the rainwater flows on the drying surface of concrete. In this case, the amount of leaching at first was large comparatively. But, it deceased with rainfall and hardly affected the environment for water as same as the continuous work of water. Investigation of a Hybrid Technique for Seismic Retrofitting of Bare Frames Md. N. Rahman andTetsuo Yamakawa Journal of Advanced Concrete Technology, 5(2) 209-222, 2007 To enhance the lateral strength, stiffness, and ductility of reinforced concrete bare frames, which are vulnerable to large seismic excitation, a simple, convenient, economic, and effective retrofit concept of cast-in-site partial or full, thick hybrid wall using additional concrete sandwiched by steel plates and high-strength steel bar prestressing is proposed in this paper. The frames were retrofitted by casting additional wing-walls adjacent to columns (referred to as opening-type wing-walls) and additional panel-walls into bare frames (referred to as non-opening-type panel-walls). The frames thus retrofitted were experimentally investigated under simultaneous cyclic lateral forces and a constant vertical load. It was verified that the proposed retrofit technique for bare frames is effective in terms of increasing lateral strength, stiffness, and ductility. For the analytic assessment of the proposed retrofit technique, design guidelines to calculate flexural strength, shear strength, and lateral force resistance capacity are suggested. Strength and Ductility of Non-Embedded Steel Reinforced Concrete Column Base Ryoichi Shohara, Yoshikazu Sawamoto, Kazumasa Imai and Haruo Nakazawa Journal of Advanced Concrete Technology, 5(2) 223-234, 2007 The non-embedded column bases of Steel Reinforced Concrete buildings were severely damaged by Hyougoken Nanbu Earthquake in 1995. Anchor bolts and main reinforcing bars were often broken. This is mainly due to the lack of consideration of the tensile force caused by the overturning moment during earthquakes. In this report the strength and deformation capacity of the non-embedded type of column bases are examined. The strength of a column base can be evaluated by the sum of the strength of the components unless the bond between concrete and reinforcing bars is deteriorated. High level tensile force deteriorates the ductility of the column base. We propose a formula to predict the deformation capacity of column bases using the parameter ﾒeffective tensile force ratioﾓ considering bond strength as well as tensile strength. Simplified Inverse Method for Determining the Tensile Strain Capacity of Strain Hardening Cementitious Composites Victor C. Li and Shunzhi Qian Journal of Advanced Concrete Technology, 5(2) 235-246, 2007 As emerging advanced construction materials, strain hardening cementitious composites (SHCCs) have seen increasing field applications recently to take advantage of its unique tensile strain hardening behavior, yet existing uniaxial tensile tests are relatively complicated and sometime difficult to implement, particularly for quality control purpose in field applications. This paper presents a new simple inverse method for quality control of tensile strain capacity by conducting beam bending test. It is shown through a theoretical model that the beam deflection from a flexural test can be linearly related to tensile strain capacity. A master curve relating this easily measured structural element property to material tensile strain capacity is constructed from parametric studies of a wide range of material tensile and compressive properties. This proposed method (UM method) has been validated with uniaxial tensile test results with reasonable agreement. In addition, this proposed method is also compared with the Japan Concrete Institute (JCI) method. Comparable accuracy is found, yet the present method is characterized with much simpler experiment setup requirement and data interpretation procedure. Therefore, it is expected that this proposed method can greatly simplify the quality control of SHCCs both in execution and interpretation phases, contributing to the wider acceptance of this type of new material in field applications. A Cohesive Interface Model for the Pullout of Inclined Steel Fibers in Cementitious Matrixes Alessandro P. Fantilli and Paolo Vallini Journal of Advanced Concrete Technology, 5(2) 247-258, 2007 The nonlinear behavior of fractured quasi-brittle materials is conventionally modeled with a fictitious crack model, which relates stresses on the crack surfaces to the corresponding crack widths. Its definition for fiber reinforced concrete is only possible by introducing a cohesive model for the matrix, and by modeling the pullout of randomly oriented fibers. To this aim, a new cohesive interface model, able to predict effectively the pullout response of inclined fiber, is presented in this paper. Based on the nonlinear behavior of steel fibers and cementitious matrixes, the proposed approach also takes into account the bond-slip relationship between the materials. By means of an iterative procedure, numerical results similar to experimental data can be obtained. In particular, maximum pullout forces at given inclination angles, as well as the complete pullout load vs. displacement diagrams, can be correctly predicted. Moreover, according to test results, the proposed approach shows, from the first pullout stage, the dependence of the response both on crushing of cementitious matrix and on yield strength of steel fibers. Comparative Tests of Beams and Columns Made of Recycled Aggregate Concrete and Natural Aggregate Concrete Andrzej B. Ajdukiewicz and Alina T. Kliszczewicz Journal of Advanced Concrete Technology, 5(2) 259-273, 2007 The tests concerning use of concrete with recycled aggregates (RAC) presented in different countries were focused on material properties. Very few tests were done on structural reinforced-concrete members with RAC. Such tests are necessary because it is difficult to predict the influence of members in particular properties on the overall behaviour of reinforced concrete members made of various mixtures of recycled aggregate concrete. The aim of the tests presented in the paper was to determine differences in behaviour of simple reinforced concrete members made of RAC in comparison with members made of concrete with natural aggregate (NAC) only. 16 series of beams and 5 series of columns have been selected for tests. The comparison of results showed similar bearing capacity of members in the series, and significantly greater deformation of concrete in members with recycled aggregate concrete. Differences in load-bearing capacity could be neglected in practice, but the differences in deformability should be considered carefully at beam deflection assessment, as well as at column shortening analysis.