Minehiro Nishiyama

DESIGN IMPLICATIONS OF A LARGE-SCALE SHAKING TABLE TEST ON A FOUR-STORY REINFORCED CONCRETE BUILDING

A full-scale, four-story, reinforced concrete building designed in accordance with the current Japanese seismic design code was tested under multi-directional shaking on the E-Defense shake table. A two-bay moment frame system was adopted in the longer plan direction and a pair of multi-story walls was incorporated in the exterior frames in the shorter plan direction. Minor adjustments to the designs were made to bring the final structure closer to U.S. practice and thereby benefit a broader audience. The resulting details of the test building reflected most current U.S. seismic design provisions. The structure remained stable throughout the series of severe shaking tests, even though lateral story drift ratios exceeded 0.04. The structure did, however, sustain severe damage in the walls and beam-column joints. Beams and columns showed limited damage and maintained core integrity throughout the series of tests. Implications of test results for the seismic design provisions of ACI 318-11 are discussed.

Durability and Seismic Resistance of an Aged Precast Prestressed Concrete Building Based on Field Inspections and Laboratory Testing

Precast prestressed concrete (PCaPC) moment-resisting frames have been applied to building constructions over 60 years in Japan. A concern recently arises about the serviceability and the seismic capacity of such existing building structures, which have often been hit by earthquakes or exposed to severe corrosion-prone environment. In this research, the former City Hall of Nandan Town in Awaji Island has been selected as a case study, which was built in 1957 as the first Japanese building using PCaPC beams. Because of its close location to the coast, the target building is considered to be exposed to a severe environment. Moreover, it was severely shaken by the Kobe earthquake in 1995, although noticeable damage was not reported by an inspection carried out several months after the earthquake. Since then several moderate earthquakes have hit it. This paper introduces the building, and describes the results of field inspection, corrosion and strength test results on concrete samples taken from the building. Seismic capacity of the building was evaluated according to the Guideline for Seismic Evaluation and Retrofit for Existing Buildings published by The Japan Building Disaster Prevention Association (JBDPA). The load carrying capacities of the beams are estimated based on the design equations for new constructions specified in the codes and guidelines published by Architectural Institute of Japan or AIJ.

BI-DIRECTIONAL LATERAL LOADING TESTS ON RC SHEAR-DOMINANT WALLS

京都大学工学研究科建築学専攻 修士(工学) 日本学術振興会特別研究員 DC 国立研究開発法人建築研究所構造研究グループ 主任研究員・博士(工学) 京都大学工学研究科建築学専攻 准教授・博士(工学) 京都大学工学研究科建築学専攻 教授・博士(工学) Grad. Student, Architecture and Architectural Engineering, Kyoto University, M. Eng., JSPS Research Fellow Senior Research Engineer, Department of Structural Engineering, Building Research Institute, Dr. Eng. Assoc. Prof., Architecture and Architectural Engineering, Kyoto University, Dr. Eng. Prof., Architecture and Architectural Engineering, Kyoto University, Dr. Eng. 日本建築学会構造系論文集 第82巻 第735号,683-692, 2017年5月 J. Struct. Constr. Eng., AIJ, Vol. 82 No. 735, 683-692, May, 2017 DOI http://doi.org/10.3130/aijs.82.683 【カテゴリーII】

CRACK OBSERVATION ON REAL BUILDING REINFORCED CONCRETE WALL WITH DEFORMED BARS AT CRACK CONTROL JOINTS AS CRACK INDUCERS

This paper describes the result of crack-inducing experiment on real building RC wall. Compared to conventional crack control joints, the proposed crack control joints with crack-inducing bars was no influence by the difference of crack-inducing bars. A crack width estimation method proposed by Ohno et al. it tended to correspond roughly to the maximum crack widths of the initial material age of actual building. There was a difference between the experimental values of the crack width afterwards.

LONG-TERM CRACK OBSERVATION ON HALF-SCALED REINFORCED CONCRETE WALL SPECIMENS WITH DEFORMED BARS AT CRACK CONTROL JOINTS AS CRACK INDUCERS

*2 京都大学大学院工学研究科 建築学専攻 修士課程 *2 Graduate student, Dept. of Architecture and Architectural Eng. Kyoto Univ. *3 京都大学大学院工学研究科 建築学専攻 准教授 博士(工学) *3 Assoc. Professor, Dept. of Architecture and Architectural Eng. Kyoto Univ. *4 京都大学大学院工学研究科 建築学専攻 教授 博士(工学) *4 Professor, Dept. of Architecture and Architectural Eng. Kyoto Univ. 誘発材に異形鉄筋を用いたRC 造耐震壁縮小試験体の長期ひび 割れ性状 LONG-TERM CRACK OBSERVATION ON HALF-SCALED REINFORCED CONCRETE WALL SPECIMENS WITH DEFORMED BARS AT CRACK CONTROL JOINTS AS CRACK INDUCERS

Shear Resistance Mechanism of Posttensioned Precast Concrete Members

An analytical model to investigate the shear resistance mechanism of a posttensioned precast concrete (PPC) member is proposed. The model is based on the truss mechanism. The compatibility of strains and the equilibrium of stresses of the shear cracked concrete, prestressing steel, and shear reinforcement are applied to the shear model. The proposed truss model consists of three stress zones (zones 1, 2, and 3). Triangle struts of cover concrete subjected to uniaxial compressive stress are defined as zone 1. Biaxial stress zones of diagonally cracked concrete between the longitudinal bar and prestressing steel are defined as zone 2. Zone 3 is defined as the diagonally cracked concrete zone between both compression and tension prestressing steels. The model considers the bond characteristics of prestressing steel. The proposed truss model is useful to predict not only shear strength, but also the shear deformation, tensile stress in shear reinforcement, and failure mode of a PPC member. By comparison of experimental and analytical results, an accuracy of analytical results by the proposed method was verified. The proposed method evaluated experimental results, which are shear strength, shear strain, and tensile stress in shear reinforcement in a good accuracy.

FLEXURAL AND SHEAR BEHAVIOR OF PRECAST PRESTRESSED CONCRETE BEAM WITH HIGH STRENGTH SHEAR REINFORCEMENT

Seven half-scale post-tensioned precast concrete beams were tested under anti-symmetrical flexure. The experimental parameters were shear span ratio and shear reinforcement ratio. Multi-strands and high strength shear reinforcement with nominal yield strength of 785 MPa were used as post-tensioning steel and shear reinforcement, respectively. Yielding of shear reinforcement was not observed in any of the specimens. The flexural capacity evaluated by the ACI rectangular concrete stress block with plane section assumption agreed well to the experimental results. The shear capacity was estimated by the design equation 71.2a in the AIJ Standard for Structural Design and Construction of Prestressed Concrete Structures. The experimental results collected by literature survey to past research revealed that shear failure modes could be related to each of the experimental parameters (shear span ratio, shear reinforcement strength and shear reinforcement ratio).

An Experimental Study on Effectiveness of Reinforcing Methods on L-Shaped Prestressed Concrete Beam-Column Joints

This paper presents experimental results of cyclic loading tests carried out on three L-shaped prestressed concrete beam-column corner joints. Three types of reinforcing methods to enhance the anchorage performance of beam and column longitudinal reinforcing bars were studied based on the experimental results such as the load-displacement relation curves, deformation capacity, prestressing force variation, and strain measurements of the beam and column reinforcing bars. The test specimens were KPCL1 with the column longitudinal reinforcement with 180-degree hooks at their ends, KPCL2 with the column longitudinal reinforcement bent in a U-shape, and KPCL3 with U-shaped column longitudinal reinforcement and additional transverse reinforcement on the beam longitudinal reinforcement. It can be concluded that the anchorage performance was somehow enhanced by the three reinforcing methods in the positive direction of loading (closing direction), while in the negative direction of loading (opening direction) there was no remarkable improvement.

ULTIMATE SHEAR STRENGTH OF PRESTRESSED CONCRETE MEMBERS CONSIDERING BOND STRESS OF PRESTRESSING STEEL

Analytical methods based on truss and arch mechanisms were proposed to predict the ultimate shear strength of prestressed concrete members. Yielding of longitudinal mild steel bars and prestressing tendons were taken into account. Bond capacity of prestressing tendons was also included in the analyses. Test results from 119 prestressed concrete beams and columns in the past literature were compared with the analytical results in terms of the ultimate shear capacity. The proposed methods gave a better and more accurate estimation of the ultimate shear capacity than the method provided in the standard for design and construction of prestressed concrete structures published by Architectural Institute of Japan. The accuracy did not depend on the experimental parameters such as shear reinforcement ratio, axial force level, shear span ratio and concrete compressive strength specified for the specimens.

Controlled Yield Sequence of Reinforcement in Concrete Members

In this paper, 2 practical methods for reducing residual deformation of structural members while providing them with adequate energy dissipation during earthquakes are offered. One method is the combined use of high and ordinary strength rebars in a structural member, while the other is graded composite strands, which consist of high and ordinary strength wires for prestressed concrete members. In these systems, ordinary strength steel provides energy dissipation due to its inelastic response and high strength steel acts as an elastic spring to reduce residual deformation or displacement.