Masanori Iiba

Experimental study on enhancement of self-restoration of concrete beams using SMA wire

Shape Memory Alloys (SMA) exhibit stable superelasticity between a reverse transformation finish temperature (Af) and approximately 30°C above Af, and therefore can sufficiently work as a superelastic material for structural use in building under the temperature in a construction environment. In order to verify the potential self-restoration capacity of mortar beams containing superelastic SMA reinforcements, static loading tests were conducted, and the results were then compared with those for a beam containing steel wires. The comparison indicates that (1) after maximum deflection, the mortar beam with SMA can return to an about one-tenth deflection compared with the maximum, (2) the range of deflection of the mortar beam with SMA is more than seven times that of the beam with steel, and (3) wide single crack can occur at the critical section due to a weaker bond force between SMA and mortar.

Seismic response control tests and simulations by fuzzy optimal logic of building structures

This paper outlines shaking table tests and their results for an active seismic response control system that uses fuzzy optimal logic (FOL). The test results confirmed the validity of the vibration control effect of this seismic response control system. The results of this study lead to two conclusions, that the effectiveness of this FOL control system can be increased by modifying the membership function, and that the results of seismic response control tests can be qualitatively evaluated by simple simulation methods.

Seismic Performance Evaluation of Seismically Isolated Buildings Introduced to the Building Code of Japan

The Building Code of Japan (the Building Standard Law of Japan) has been changed from the former prescriptive type into a performance-based type in June, 2000. This paper presents the evaluation procedures for seismic performance of seismically isolated buildings against major earthquake motions newly introduced to the Building Code of Japan in October, 2000. The evaluation procedures apply the equivalent single-degree-of-freedom (ESDOF) system, equivalent linearization and response spectrum analysis. The basic concept of seismic design spectra for major earthquake motions is (1) basic design spectra defined at the engineering bedrock, and (2) evaluation of site response from geotechnical data of surface soil layers. The principle of evaluation procedures is that the predicted response values should not exceed estimated limit values. The evaluation criteria of each portion of a building are (1) the isolation system shall be designed so that the maximum response displacement does not exceed the design limit displacement, and (2) the structure above the isolation system and the foundation and structural elements below the isolation system shall be designed so that the working stress does not exceed the allowable stress. The scope of application of the evaluation procedures is (I) buildings not exceeding 60 meters in height, and (2) base isolation buildings on the soil layers excluding very soft soils.

Recorded Responses of Building Structures during the 2011 Tohoku-Oki Earthquake with Some Implications for Design Practice

During the 2011 Tohoku-oki earthquake, a large number of response records from various types of buildings were obtained. The records give us the actual motions of buildings during the exceptionally large earthquakes that are considered comparable with design earthquakes. Various types of earthquake response records have been collected, and their properties with several buildings that will exhibit implications for structural design are discussed.

Seismic Behavior of a Newly Developed Base Isolation System for Houses

abstract The good performance of seismically isolated structures during the 1995 Kobe earthquake persuaded structural engineers, isolator manufacturers and housing construction companies to undertake a cooperative research project to investigate the possibility of introducing the seismic isolation technology in Japans private housing sector. As a part of this project, in this study, the seismic performance of a recently developed Friction Pendulum System (FPS) for houses is presented. In order to verify its behavior under recorded earthquake ground motions, 3-dimensional shaking table tests were conducted. A three-dimensional nonlinear model was used to simulate the experimentally recorded acceleration and displacement response. Experimental results showed that the FPS significantly reduced the acceleration response at both moderate and strong levels of input ground motion. The analytical model used in this study satisfactorily predicted the experimentally recorded acceleration and displacement response time histories.

INVESTIGATION OF OSCILLATORY PROPERTIES OF SCHOOL GYMNASIUMS

In this paper, oscillatory properties of two school gymnasiums are investigated based on microtremor observation, forced vibration tests and seismic observation. The roof forms of the gymnasiums are different, one is a hip roof and the other is a gable roof. At each gymnasium, influences of the roof forms on the natural frequency or damping ratio, etc. are investigated. And using the observation and tests results, the validity of the dynamic analysis model is discussed.

A STUDY ON METHOD TO EVALUATE SEISMIC AMPLIFICATION RATIOS OF SURFACE STRATA

A simple method for estimating the seismic amplification characteristics of surface strata is proposed by using the response spectrum method within the capacity-spectrum design scheme. The following presentations and discussions are made in this article: 1) to compute the natural and equivalent site periods based on the modal analyses of the multi-degree-of-freedom (MDOF) soil systems, 2) to determine the effective shear strain in surface soil, and 3) to examine the reliability and accuracy of the proposed method compared to SHAKE analysis.

Seismic Evaluation Procedures of Seismically Isolated Buildings Introduced to the Building Code of Japan

The Building Code of Japan (the Building Standard Law of Japan) has been changed from the former prescriptive into performance-based type in June, 2000. This paper presents the evaluation procedures of seismic performance of seismically isolated buildings against major earthquake motions newly introduced to the Building Code of Japan in October, 2000. The evaluation procedures apply the single-degree-of-freedom (SDOF) system, equivalent linearization and response spectrum analysis. The basic concept of seismic design spectra for major earthquake motions is: 1) basic design spectra defined at the engineering bedrock, and 2) evaluation of site response from geotechnical data of surface soil layers. The principle of evaluation procedures is that the predicted response values should not exceed the estimated limit values. The evaluation criteria of each portion of a building are: 1) the isolation system shall be designed so that the maximum response displacement does not exceed the design limit displacement, and 2) the structure above the isolation system and the foundation and structural elements below the isolation system shall be designed so that the working stress does not exceed the allowable stress. The scope of application of the evaluation procedures is: 1) buildings not exceeding 60 meters in height, and 2) base isolation buildings on the soil layers excluding very soft soils.Copyright