Hiroshi Isoda

Damage Assessment of a Full-Scale Six-Story Wood-Frame Building Following Triaxial Shake Table Tests

In the summer of 2009, a full-scale midrise wood-frame building was tested under a series of simulated earthquakes on the worlds largest shake table in Miki City, Japan. The objective of this series of tests was to validate a performance-based seismic design approach by qualitatively and quantitatively examining the buildings seismic performance in terms of response kinematics and observed damage. This paper presents the results of detailed damage inspections following each test in a series of five shake table tests, and explains their qualitative synthesis to provide design method validation. The seismic test program had two phases. Phase I was the testing of a seven-story mixed-use building with the first story consisting of a steel special moment frame (SMF) and stories 2-7 made of light-frame wood. In Phase II, the SMF was heavily braced such that it effectively became an extension of the shake table and testing was conducted on only stories 2-7, making the building a six-story light-frame multifamily residential building instead of a mixed-use building. All earthquake motions were scalings of the 1994 Northridge earthquake at the Canoga Park recording station with seismic intensities ranging from peak ground accelerations of 0.22 to 0.88 g. The building performed quite well during all earthquakes with damage only to the gypsum wall board (drywall), no sill plate splitting, no nails withdrawing or pulling through the sheathing, no edge tearing of the sheathing, no visible stud splitting around tie-down rods, and reasonable floor accelerations. On the basis of damage inspection, it was concluded that it is possible to design this type of building and keep the damage to a manageable level during major earthquakes by utilizing the new design approach. DOI: 10.1061/(ASCE)CF.1943-5509.0000202.

Damage detection tests of five-story steel frame with simulated damages

This paper presents damage detection tests of five-story steel frame with simulated damages. We discuss pre-analytical study and results of experiments. Fiber brag grating (FBG) sensors, accelerometers, strain gauges and laser displacement meters are installed in this test frame. We assume damages by removing studs from only one story, loosening bolts of beams, cutting part of beams and extracting braces from only one story. From the results of pre-analytical study, we can estimate which story is damaged from the change of natural period and mode shape to some extent. We applied flexibility method which is one of a damage identification methods using modal properties. We also apply flexibility method to results of experiments. In some cases we can estimate which story is damaged, and in other cases we cannot. We also applied a method using multiple natural frequency shifts. Making use of the change in five natural frequencies due to damage, the location of damaged stories can be pinpointed. In both methods, we cannot identify damaged story in some cases. Some methods other than methods using modal properties have to be tried to apply in such cases.

Modeling and measurement for health monitoring of an existing SRC eight-story building

The final purpose of our study is development of the structural health-monitoring technique for the real existing buildings. In this paper, the results of the analytical studies are shown as the first step of our health-monitoring scenario. One of the purposes of the first step is to make the analytical models for evaluating the structural performance.

Timber–Reinforced Concrete Core Hybrid System: Shake Table Experimental Test

AbstractThe law to promote the use of wood in the construction industry was announced by the Japanese government in 2010. As a result of this initiative, timber and timber-based hybrid buildings are increasingly used in public buildings. As the buildings are located in high seismic zone areas, however, validation of the current design guideline was of paramount importance. This paper reports the design and a shake table test of timber frame–reinforced concrete (RC) core hybrid systems. Three specimens (S1, S2, and S3) are tested: S1 and S2 are both one-story buildings with a nailed plywood floor (flexible diaphragm) and a rigid RC floor (rigid diaphragm), respectively. S3 is a two-story building with a nailed plywood floor. Each specimen is tested with increasing magnitude of earthquake loading. The shake table test results showed that the adopted design guideline is sufficient. At higher seismic loads, however, the prevalent plan irregularity induced higher torsional demand damage at the RC core and timb...

RESIDUAL SEISMIC PERFORMANCE OF WOODEN HOUSES WITH PLYWOOD LOAD-BEARING WALL AFTER EARTHQUAKE: －Research on seismic behavior of wooden houses Part VI－@@@－木造住宅の地震時挙動に関する研究 その６－

* 信州大学大学院 修士課程 * 京都大学生存圏研究所 教授/建築研究所 客員研究員・博士(工学) * 独立行政法人建築研究所構造研究グループ 研究員・博士(工学) * 筑波大学大学院システム情報工学研究科博士課程 修士(工学) * 筑波大学システム情報系 教授・工博 * 信州大学工学部 助教・博士(工学) * 信州大学工学部 教授・工博 Grad. Stud., Graduate School of Engineering, Shinshu Univ. Prof., RISH, Kyoto Univ./ Visiting Researcher, BRI, Dr.Eng. Research Engineer, Dept. of Structual Eng., BRI, Dr.Eng. Grad. Stud., Graduate Sch. of Systems and Information, Univ. of Tsukuba, Mr.Eng. Prof., Faculty of Engineering, Information and Systems, Univ. of Tsukuba, Dr.Eng. Assist. Prof., Faculty of Engineering, Shinshu Univ., Dr.Eng. Prof., Faculty of Engineering, Shinshu Univ., Dr.Eng. 日本建築学会構造系論文集 第81巻 第728号,1683-1690, 2016年10月 J. Struct. Constr. Eng., AIJ, Vol. 81 No. 728, 1683-1690, Oct., 2016 DOI http://doi.org/10.3130/aijs.81.1683 【カテゴリーIII】

AN ANALYTICAL STUDY ON LARGE DEFORMATION STATIC BEHAVIOR CONSIDERING BREAKING JOINTS OF WOOD HOUSES

This paper attempts to predict analytically large deformation static behaviors of two story wooden frame walls from the static performances of members and joints which compose wooden frame houses and walls. Wooden frame walls in this study have fragile joints which need to consider repeated contact problems, therefore extended distinct element method (EDEM) are applied which can consider these problems.110 joint specimens are tested. They are pressed in axial side, bent inside and outside. From the results of these tests and the past researches, the two story wooden frame walls are modeled. Especially, because of the brace failure modes of pressing side, four kinds of models are proposed for each wooden frame wall. The comparison of the results between EDEM analyses and tests indicates, 1) in the range of assumed brace failure mode, proposed models can predict test results, 2) by considering brace models in detail, proposed models can reproduce test results precisely.

AN EXPERIMENTAL STUDY ON LARGE DEFORMATION PERFORMANCES OF WOOD HOUSES CONSIDERING THE BREAK OF JOINTS

This paper attempts to clear large deformation behaviors of two story wooden frame houses and to predict large deformation behaviors of two story wooden frame houses from the summation of static performances of two story wooden frame walls that compose those houses. 4 types of wooden frame houses and walls are tested. The comparison of the results between two story wooden frame houses and the summation walls indicates, 1) until 1/30-1/25rad. deformation of 1st story, the summation of walls can predict structural performances of two story wooden frame houses without the influence of joint type of the column or the existences of boards, 2) after 1/25rad. deformation of 1st story, the structural performance of the summation of walls become different from that ones because failure modes of brace in walls is different from those of houses.

EXPERIMENTS FOR EFFECTIVE MASS AND SEISMIC BEHAVIOR OF FURNITURE

The evaluating method of seismic load has been studied as the matter how to be ruled safety and reasonably from long ago in Japan. Some calculation formulas to lay down the value of seismic load were suggested, but they were based on incomplete evidence such as by heuristics or expectancy. This seismic load value used the same one ruled over 65 years ago without logical way of evidence by inspection is applied to the current Building Standard Low. In this study, we implemented the shaking table test of furniture with horizontal load cell. By seismic behavior of furniture, the observed value by load cell will be supposed to be reduced cause of their “Effective Mass”, whici has an effect on horizontal shear force. The purpose of this paper is: 1) Watching seismic behaviors of furniture in various installation conditions, 2) Working out the “Effective Mass” of furniture in the logical way, 3) Weighing between observed behavior and “Effective Mass”.

SHAKING TABLE TEST FOR WOOD CONSTRUCTION WITH REINFORCED BRICK

This paper presents the seismic performance of wood construction with brick exterior. Shaking table tests were conducted to evaluate behavior during severe earthquakes and shear wall test of brick was also conducted to compare the shear performance with wood shear wall. As the result of the tests, story drift during JMA Kobe wave was less than 0.5% which is the limit state of damage and no damages were observed in structural element. It is confirmed that target structure have enough seismic performance in comparison with normal wood construction.

STUDY ON STRUCTURAL PERFORMANCE OF A WOOD POST-BEAM CONSTRUCTION WITH INSULATED PANEL

This paper describes the structural performance of shear wall, structural floor and joint between panel and timber frame in a construction using wood panel inserted heat insulation. The structural key issue of this construction is to evaluate shear performance in difference with thickness and variant of the insulation, composite action of outer oriental strand board and inner insulation, and with or without timber supports being in the panel. Their performance was evaluated in experimental study and the shear performance of wall was predicted from single connector property analytically.