This study aimed at proposing a new drying shrinkage testing method which enables us to save testing labor. For this purpose, Four testing methods were experimentally investigated in comparison with standard testing method specified in Japanese Industrial Standard. As a result of this experiment, a method adopting cylinder specimen embedded mould gage showed highest reproducibility and consistency with the standard method and were revealed an appropriate for this proposal. This proposing method was also demonstrated robustness and high reliability in field experiment and is expected to contribute to rational shrinkage controlling at construction sites.

抄録全体を表示

It is important to estimating seismic structural demands simply and precisely for structural performance assessment and for design. Nonlinear dynamic analysis (NDA) is generally used to evaluate structural response to a given ground motion, and the result is considered to be rigorous. However, there exists uncertainty in the strength of structural components, and structural response to the ground motion should be considered as a random variable. In this sense, NDA using a deterministic structural model can be considered as one of predictors of structural demands. In this paper, the influence of the uncertainty in strength of structural components on structural response is investigated considering spectral characteristics of ground motions. Then the accuraccy of NDA using deterministic structural models as well as simple predictors such as Calculation of Response and Limit Strength and Inelastic Modal Predictor is investigated using numerical examples.

抄録全体を表示

When cladding on a windward wall of a building is broken by a severe storm, the internal pressures may be rapidly increased. The sudden increase of the internal pressure is mentioned as “Aerodynamic Overshoot”, which may cause further damage to other cladding and interior components. This paper investigates the estimation of Overshoot-ratio using a non-dimensional parameter that characterizes the Overshoot phenomenon. This parameter is defined by using the wall opening area, the internal volume of the building, the incident wind speed and the pressure-loss coefficient of an opening. A result of field measurements suggests that the Overshoot-ratio has the values of 1.1 to 1.2 for usual size buildings. As a result, design wind loads for components and cladding on a building should be decided by using the peak internal pressure coefficient of 1.0 in order to prevent the expansion of damage caused by a wall breakages.

抄録全体を表示

In this paper we design a gain-scheduled (GS) H_∞ controller of a semi-active seismic isolation system using a large-scale 40 kN-class magneto-rheological fluid (MR) damper for a multi-degree-of-freedom structure. By introducing a fictitious damper model we can transform the bilinear model into a linear parameter varying (LPV) model for which designing of a GS controller based on linear matrix inequalities (LMIs) is available. For verification of the control performance we carry out simulations and shaking table tests for some kind of earthquakes using the 40 kN-class MR damper. In comparison with a passive damper it is verified that the proposed method has good performance.

抄録全体を表示

In this paper, we discuss the propagation process of ground motions generated by two earthquakes through the analysis of seismograms recorded on rock and sediment sites. Significant later phases following the S-wave arrivals in horizontal components often appear in the ground motions recorded in the sedimentary plain. We applied 2-D finite difference method to simulate the later phases during the earthquakes observed at the sediment sites using the subsurface structures derived from the seismic and microtremors prospecting process. The results indicate that when considering basin-excited waves, the characteristics of the simulated waveforms including the later phases display good agreement with the observed seismograms. Moreover, the earthquake motion characteristics were clarified by the propagation process of seismic waves in the western part of Nobi Plain. We also clarified effects of the irregular underground structure on the Basin-Induced Love waves propagation.

抄録全体を表示

Present paper proposes a supporting system for structural design of steel frame structures by using multi-objective genetic algorithm. Most of steel structures are composed of the standardized members produced at the factory. In order to take such situation into the process of structural optimization, the structural optimization scheme through the usage of genetic algorithm which can easily deal with discrete variables is presented. Furthermore, multi-objective optimal design method to obtain the Pareto solutions considering both structure's safety and its economy by using multi-objective genetic algorithm is proposed. Through the numerical examples, present design system is shown to be useful for designers as a valuable proposal tool especially in the beginning stage of the structural design.

抄録全体を表示

In most cases, it's quite difficult for structural designers to perform many case studies when they plan a layout of earthquake resistant elements in a preliminary architectural design. So it would be helpful for them to know the characteristics of optimum designs, which can be regarded as standard design, with respect to the changes of numbers or layouts of earthquake resistant elements.
In this paper we present characteristics of optimum designs of steel plane frames with respect to layouts of multi-story braces through an examination of optimum designs by examining optimum design solutions of multi-story frames with various layouts of braces.

抄録全体を表示

For the design of pile foundation under vertical load, the amount of the settlement is important as well as the bearing capacity. So it is necessary for the establishment of the method to calculate the settlement exactly. The technique to estimate the load-settlement relations is examined in this paper based on many vertical loading tests of preboring nodular piles. For the calculation of load-settlement relations, the load transfer analysis is applied with the frictional resistance and point resistance in unit area by digging diameter estimated from N-value of the ground. The results of estimation by proposed method are closed to the measured values.

抄録全体を表示

Authors have already shown that the damage to buildings and the foundations in Hanshin-Awaji Earthquake can be arranged by those natural periods. Many of those cases were pile foundations. In this paper, first of all, the structural characteristic coefficient Ds including the influence of the ground was examined. Soil-structure interaction system was applied to pile foundations, and the above-mentioned result was verified by the numerical analysis in the ground and the building that had been modeled like showing the damage case. It was shown to be able to explain the verified tendency according to the difference of the rigidity between the superstructure and the pile foundation. In conclusion, it was shown that it was more reasonable to use the stiffness ratio of pile foundation that was similar to the definition with the column and considered the influence of the ground for an earthquake-proof design than to use an underground seismic intensity in the pile foundations.

抄録全体を表示

The main purpose of this study is to investigate, mainly experimentally, the strength and the relationships between damaged patterns and vibratory characteristics of retrofitted reinforced concrete cylindrical shells. The damage of shells could be encountered by natural disasters and long-term deterioration. However the strength and its vibratory characteristics of retrofitted reinforced concrete shells is difficult to estimate. The retrofit of concrete shells was applied with both grouting mortar and carbon fiber sheets. A loading experiment was applied on concrete shells under concentrated load. Before and after the loading experiment, vibratory tests by an impact hammer and an oscillatory machine were applied. The vibratory characteristics distilled from specimens before and after loading experiment were examined. The relationships between vibratory characteristics and mechanical behaviors of the retrofitted specimens before and after loading experiment were discussed on the basis of the results of the vibratory tests and the loading experiment.

抄録全体を表示

In this paper, the formula to evaluate the required tensile capacities of connections at column's top and bottom for conventional post and beam structural system having sheathed walls with openings, which are extended assuming rigidity of beams and floors in three dimensional structures from one previously derived assuming rigidity of beams in plane structures by authors, is presented and experimentally verified.The formula to evaluate normal force of column consists of the sums of the dead normal force, the normal force caused from the over turning moment by the horizontal shear force acting on upper stories, and vertical shear force produced in the shear wall carrying the shear resistance. The formula has been verified by carrying experiments on a two story three dimension structure with 26 kind variables. Dividing three dimension effect into perpendicularly arranged columns and walls effect to loading direction, the generating mechanisms have been experimentally made clear. For the variable of the bending stiffness of beam, experiments clearly shown that the beam deformation could not been disregarded.

抄録全体を表示

We carry out earthquake response analyses of two Nagaya models with uni-axial eccentricity considering the floor stiffness and examine the orthogonal wall effects. The effect means how walls perpendicular to the eccentric direction will control the torsional vibration. The two different Nagaya models are one- and four-unit types. We choose the floor stiffness, shape ratio of the length to the width on the plan, eccentric ratio, wall quantity and the wall ratio, and kinds of input motions and their maximum value in the analyses as parameters. The results obtained show that the factors of the orthogonal wall effect are mainly the floor stiffness and shape ratio, and that the demand ratios are 2.0 and 1.5 for the two models. The kinds of input motions and their maximum values do not become to the factors of the effect.

抄録全体を表示

The authors have been researching and developing methods of retrofitting existing reinforced concrete buildings with friction dampers. Using an existing school building which will be demolished in the future, the authors conducted full-scale seismic tests to verify the effects of response control retrofit on actual buildings. Elasto-plastic behavior of an existing reinforced concrete school building seismically retrofitted with braces fitted with friction dampers was examined by comparing the results of a full-scale seismic test with analytical results. The analysis confirmed that applying braces with friction dampers could produce a similar retrofit effect to that verified by the test, and reproduce the behavior of the actual building accurately. The damage mitigation effect obtained by the retrofit procedure was identified from the absorbed hysteretic energy of each member and energy spectra.

抄録全体を表示

Tests have been carried out on three frame specimens that consist of pre-cast concrete units and high strength steel bars. The specimens have both of environmental and seismic features. The former is that constructing and destructing cost is able to be reduced because the each unit is fabricated in factories and is combined at dry type joints by using unbonded post-tensioned bars. The materials are more available to be recycled than those of the conventional RC frames. The later is that self-centering capability results in essentially no residual drift after seismic excitation. The construction method and the structural behavior under cyclic lateral load of these proposed frame specimens are investigated experimentally. The post-tensioned bars are set through the ducts embedded in the concrete columns and connect of each columns successfully as to the constructing procedure planed. The self-centering characteristics are also obtained by the test results as our expectation. The designed column-yielding mechanisms of the frame specimens are realized and the lateral load carrying capacities are estimated precisely on the bases of the calculated flexural capacities of the concrete and the measured tensile strengths of the steel bars.

抄録全体を表示

Extensive researches have been conducted on the application of eccentric beam-to-column connections in the steel frames composed of square tubular columns. For eccentric beam-to-wide-flange column connections, fewer efforts have been made in the past. This paper presents the local yield strength of the eccentric beam-to-wide-flange column connections. For the connection stiffening, both transverse stiffeners and vertical stiffeners are employed. By applying the yield line theory, strength formulae of the beam flange-to-column connections are derived for five different types of collapse mechanisms. Six loading tests are performed for the local connection models to examine the elastic-plastic behavior of the connections with eccentricity. The measured strain distributions and the residual flange deformations confirm the validity of the collapse mechanism including beam-flange rotation.

抄録全体を表示

In our previous paper, it is shown that story drift concentration is restraint by columns of two braced frames with pinned and fixed column bases. But embedded column bases are nearly fixed and exposed column bases are nearly pinned in the real structures. These column bases is designed as rotational springs. In this paper, the equations of the drift concentration factor for two story braced frames with columns base of rotational springs have been developed from the equilibrium conditions of the frames subjected to lateral force. This paper clarifies the relationship between drift concentration and ratio of column flexural stiffness and column rotational stiffness.

抄録全体を表示

Maximum stress obtained by compression test of circular steel stub-columns were compared with deformation theory and incremental stress-strain theory. Each buckling analysis has a term of tangent modulus E_t in its solution. Therefore these solutions are commonly considered that all specimens lose stability in the plastic-flow region. This paper shows that specimens with small diameter-to-thickness ratio can be compressed beyond plastic flow region by reconsidering past plastic theories.

抄録全体を表示

This paper presents a two-dimensional structural model of an exposed column-base, that take into account initial tensioning of anchor bolts and column axial force. The applicability of this model is confirmed through loading tests on a canti-lever with exposed column-base subjected to horizontal forces.
The following observations were made:
1) The model take into account of variation of rotational rigidity due to initial anchor bolts tensioning and axial force of column-base.
2) The model adjust the maximum bending moment capacity and rotational rigidity by changing the line of action of the compressive force line and rigidity modification coefficient.
3) The result from the present model agree closely with loading-tests results.

抄録全体を表示

Ductility reduction factor Ds used in second phase design is based on the energy constant rule proposed by Newmark. In addition, it is also important to set a story drift limit to the structure on seismic design. Accordingly, allowable story drift and Ds factor are required to consider in design; however, the building code does not specifically address the relationship between these two values. The duration of the ground motion has less effect on the structure that has spindle-shaped response. On the other hand, the structure having an origin progress slip response will cumulate the deformation during the seismic event; response deformation will increase lineally with the cycle of earthquake and f value. As a result, the relationship between allowable story drift and Ds factor for origin progress slip response structure should consider the characteristic of input ground motion.
In this paper, firstly, Ds factor for the structure shows origin progress slip responses are discussed based on energy method and a formula for Ds factor based on cumulative plastic deformation ratio is proposed. Secondly, the relationship between allowable story drift and Ds factor for origin progress slip and the hybrid of origin progress slip and spindle-shaped responses are discussed. The results obtained from this research will make it possible to apply through dynamic analysis to second phase design uniformly. Finally, controversial point of current Ds formula is clarified from the comparison study between proposed Ds formula.

抄録全体を表示

Furniture and nonstructural components in high-rise buildings are subjected to intense seismic responses. To obtain physical data on their seismic behaviors, shaking table tests are conducted. A two-story frame is built on a concrete slab supported by rubber isolators. Cladding walls are fastened in the exterior frames. Furniture is placed on the sectioned floor. The design process of the test system is presented, and its vibration characteristics are considered. Preliminary seismic response analyses for a generic thirty-story building are conducted and referred to. Designed waves are input into the shaking table to produce the equivalent floor responses in the test system.

抄録全体を表示

The derivation of the joint probability density function of non-normal random variables in the above paper is discussed as follows:
1) The relationship between the non-normal random variable and the standard normal random variable is generally nonlinear and Eq. (2) in the paper is generally incorrect.
2) The correlation coefficient between the standard normal random variables transformed from the non-normal random variables is generally different from that between the non-normal random variables.
3) The joint probability density function of non-normal random variables derived in the paper is generally incorrect.

抄録全体を表示

The authors thank Yan-Gang Zhao and Hideki Idota for their discussion. The answers are as follows;
(1) We corrected the description of the definition of normalization according to their indication. And also we corrected the description related to the correlation coefficient ρ_0,12 and the equation ƒ(χ₁, χ₂)
(2) The cause of other indications seems to be the normalization. Joint probability density function for non-normal random variables was derived by bivariate normal distribution function. In the process of derivation, we used the normalization at any point of non-normal random variables. By this normalization the equivalent normal distribution can be gotten according to the point. Then the mean and standard deviation of the equivalent normal distribution are different at each point. But in the process of derivation, normal variate by normalization is transformed to standard normal variate, whose mean and standard deviation is zero and one respectively, even though the points are different. Finally the random variables included in the derived equation are standard normal variates and the original distribution function. So we think the derivation is correct.

抄録全体を表示