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In order to clarify effects of earthquake motion and aging on dynamic characteristics of wooden houses, earthquake records at a seismically isolated wooden house for 10 years are summarized. The predominant period and amplification factor of the 2-story superstructure are compared, based on acceleration amplitude of earthquake motion, drift angle of first story, and time after completion. The predominant period is longer with increasing the acceleration amplitude and the story drift angle. The average predominant period for two years after 8 years is longer than that of first two years by 2.9-12.2%. The dependency of acceleration amplitude and time on the amplification factor is not clear.

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 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.

To make sure the relationship between strong ground motions and building damages, dynamic earthquake response analyses of a building, which had a slight damage during the 2007 Niigata-ken Chuetsu-oki earthquake, are performed. Earthquake records at ground surface have been observed by the K-NET system near the building. Also the building responses were observed during after-shock. The analysis model of the building is estimated based on results of a push-over analysis. Sway and rocking impedances are also installed in this model. The predominant frequency of the building in elastic condition is corresponding to that in after-shock observation. It is demonstrated that the response of the building, which is calculated considering the nonlinear characteristics of soil and building during the main-shock, is larger than the estimated response based on the damage situation of the building.

In this paper, vibration characteristics of 43 middle-rise reinforced concrete buildings located in Kyoto city were investigated based on microtremor measurements. The buildings can be divided to three types by judging from the structural specifications. The vibration characteristics of soil around the objective buildings were also investigated. As the influences of soil-structure interaction were evident, we used a model including swaying and rocking behavior of soil in the analysis. The natural frequencies of the three-type buildings were compared, and their statistical properties were evaluated.

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 (1) buildings not exceeding 60 meters in height, and (2) base isolation buildings on the soil layers excluding very soft soils.

The seismic design provisions of buildings in Japan was revised toward a performance-based structural engineering framework in 2000. The provisions provide two performance objectives: life safety and damage limitation of a building at two corresponding levels of earthquake motions. The design earthquake motions are defined in terms of the acceleration response spectra specified at the engineering bedrock to take account of the soil conditions and soil-structure interaction effects as properly as possible. The seismic performance shall be verified by comparing the predicted response values with the estimated limit values of a building.

The good performance of seismically isolated structures during the 1995 Kobe earthquake persuaded structural engineers, isolator manufacturers and housing construction companies to undertake a coop...

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.

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 © 2002 by ASME