There is not much possibility of damaging concrete in structures by sampling the small size cores whose diameters are from 18 to 25mm. In the present paper, the results of compressive strength test by small size cores and standard size cores which are 100mm in diameter and 200mm in height are discussed. Test results are summaried as follows : 1)Small size cores show different pattern of fractures according to the location of coarse aggregates, 2)the estimaton method by small size core has practical merit due to sampling efficiency, 3)the difference of strength of small size cores from that of standard size cores is almost constant.

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Nitrogen oxides in exhaust gases from automobiles have been causing so serious air pollution in urban areas that building materials with a NOx removal performance have been required. We have developed a photocatalytic concrete with an oxidative NOx removal performance by means of a photocatalytic activity of titanium dioxide. The photocatalytic concrete is used for paving blocks. We researched the influence of various factors on the NOx removal performance of the photocatalytic paving blocks. As a result, it turned out that the paving blocks had the performance by which NOx was removed from the ambient air on a roadside.

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In the present paper, in order to apply color measurement as a method for the quality control of younger concrete cast during a few months, the influence of various factors on the surface color of mortar under various curing conditions, and the possibility of estimation of mechanical characteristics such as dynamic elastic modulus, and flexural and compressive strength by measuring surface color and water content of mortar are investigated. It is clarified from the experiment that there is a comparative correlation between color, water content and mechanical characteristics, and it is possible to predict the dynamic elastic modulus and the compressive strength of mortar by measurement of its surface color and water content during a few months from placing concrete.

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This paper describes experimental results on yield value model of fresh mortar dependent on pressure and time obtained by a simple shear test, and the conclusions are as follows. 1. The relationship between yield value and time is linear, at least one hour after mixing of mortar. 2. The cohesion increases depending on the time, but the angle of internal friction hardly changes. 3. The change of cohesion by time becomes remarkable as the pressure increases. 4. The change of parameters in the model by water-cement ratio is similar to that of concrete slump.

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This study proposes an unique technique for improving qualities of concrete with recycled concrete coarse aggregate; a decompression and rapid release (DC-RR). The DC-RR procedure is applied after normal mixing of concrete with recycled aggregate. Through the DC-RR procedure, the micro structure of interfacial transition zones between recycled aggregate and new matrix mortar are estimated to be dramatically improved. In this paper, experimental studies with full scale specimens are described on the effectiveness of the DC-RR procedure on the performances of concrete structures with recycled concrete coarse aggregate, such as core strengths of columns, defections of slabs and crack widths of walls. It was found that, by applying the DC-RR procedure, the performances of full scale concrete specimens with recycled coarse aggregate were much improved and evaluated as almost equal to those with natural coarse aggregate.

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In this study, It is investigated the relationships between deteriorations of finishing materials and carbonation of concrete using a model building at the age of 11 years. It is measured the carbonation depth, deterioration of finishing materials, and so on. And, it is carried out the accelerated carbonation test on the specimens after natural exposure test. According to the results, some natural exposure test results are different from accelerated carbonation test results on same conditions specimens. So, it seems that it is important to take account into durability of finishing materials for evaluation on the protection effects.

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High-rise buildings are being increasingly constructed with vibration control devices or isolation devices. It is necessary to estimate the responses of these buildings in the high wind speed region where self-excited vibrations occur, such as self excited vortexinduced viberation, galloping and torsional flutter, in relation to their ultimate limit stage or damage control provided by their control devices. This paper proposes a spectral analyzing method and a time history analyzing method using motion-induced wind force for wind responses of high-rise buildings with coupled across-wind and torsional vibrations, and discusses the validity of these methods. Results of spectral analysis considering coupled motion-induced wind forces show that the response to across-wind vibration increases at the wind speed at which the torsional response increases rapidly, when the natural frequency of across-wind vibration is lower than that of torsional vibration.

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When estimating snow load on a building roof in a heavy-snowfall district, it is important to know its volume and drift. Snowdrift on a building is closely related to the wind flow pattern around a building. The purpose of this study was to clarify the relationship between snowdrift and wind flow on buildings, and to thus predict the snowdrift from wind flow patterns. This paper investigates snowdrift and wind flow around a model building with stepped flat roof. Snowdrift patterns on model roofs were observed from field measurements in Hokkaido. And wind velocity patterns around the model were measured by wind tunnel tests. Then some relativity was found in snowdrift and wind acceleration in the vicinity of roof surface.

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Semi-active control method, which is to maximize the energy transmission from main structure to sub structure using dynamics of the sub structure fully, is proposed. The method ensures the stability of the main structure naturally and restricts the number of state value for control. These features are useful for practical use. The analytical results presented are for a SDOF model, which is controlled by means of semi-active oil damper verified already, with sinusoidal wave input and earthquake wave input. The influences of various parameters on the characteristics of the sub structure and control device are verified.

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This paper presents a supervised classification method using a neural network to classify typical landforms based on a land cover map and a Digital Elevation Model (DEM). The proposed method classified the landform of Kobe city in Japan into hill, plateau, fan and reclaimed land. As a result, a Self-Organizing Map(SOM) produces the higher classification accuracy than Back Propagation method. Furthermore, we adopted these classified landforms for a ground motion estimation in Kobe during the 1995 Hyogoken Nanbu earthquake, and could obtain detailed ground motion distribution compared with the one based on the Digital National Land Information (DNLI).

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While the seismic intensity scale shows the level of ground shaking, it is closely related to the building damage during earthquakes. The seismic intensity data are analyzed with the aim of applying to the estimation of seismic damage. The relative value of seismic intensity at an intensity observation site can be evaluated considering the local site amplification of ground motion. The local site amplification of seismic intensity is obtained from the one-dimensional multiple reflection analysis based on the soil boring data. The seismic intensity distribution of recent moderate earthquake in Tokyo metropolitan area is considered in correlation to the Ansei-Edo earthquake. It is concluded that the seismic intensity distribution of major earthquake can be evaluated using the attenuation equation and site intensity amplification data.

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We investigated earthquakes in Japan, where strong ground motion records coincided with building damage data, examining correlation between various indices of seismic destructive power and building damage ratios. We also carried out earhtquake response analyses and calculated responses to one-cycle sine-wave inputs. We proposed the average elastic acceleration or velocity response at periods from 1.2 to 1.5 s with a damping factor of 0.05 as an optimum destructive power index of strong ground motion for predicting building damage ratios. The period range is based on the equivalent periods that are calculated for residences with typical elastic periods considering inelastic elongation. We then formulated the vulnerability function using this proposed index and modified the JMA seismic intensity scale for obtaining better correlation with actual building damage.

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On base-isolated structure, soil amplification is an important factor in a seismic design based on limited strength method. For base-isolated houses, soil surveying using boring is relatively expensive. This paper proposes a simplified evaluating method of soil amplification factor using only ground period based on the simulation of soil amplification by limited strength method. And seismic response charts using equivalent liner method considering the proposed factor is presented. When the site ground period is determined, immediately the chart shows the response displacement which is the most important criteria on base-isolated houses, and help the isolated judgment. The proposed method is verified by comparing to complete analysis.

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This paper presents an effective method for designing structures using a cellular automaton, representing a simple conceptual basis for the self- organization of structural systems. The proposed methods are sufficiently simple to solve topology optimization problems as pure 0-1 problems, and yet sufficiently complex to express a wide variety of complicated topologies. Local rules for the birth and death of cells are all that is required for this method, dependent on the type of design constraints, such as weight, stiffness and frequency. The effectiveness of the proposed method is demonstrated through numerical topology optimization problem examples. The method proposed in this paper offers a new approach to structural optimization, overcoming most of the problems associated with traditional techniques.

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This paper presents the results of dynamic analyses conducted with the aim of considering the damage of building supported by ductility piles. Soft first-story structure and frame structure were objects of analyses. Ductility piles were modeled as nonlinear beam with moment-curvature relation influenced by axial-force fluctuation. The pile-supported structure was connected with free ground by nonliner Winkler springs. These analytical results indicated that the hysteretic damping of pile heads decreases the energy dissipation of upper structure, and thus the damage of upper structure can be controlled by ductility pile.

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The shaft friction of a pile under rapid loading has been considered to be composed of radiation damping, viscous damping and stiffness of soil. The stiffness and the radiation damping of soil can be determined by laboratory tests and numerical analyses, but an appropriate testing method has not been established on the viscous damping at pile - soil interface. The object of this paper is to devise an apparatus to investigate the viscous damping at pile - soil interface. By rotating a cylindrical rod of a 31.8mm diameter embedded in a clay specimen with various speeds, the dynamic torque resistance is measured and the viscous damping is evaluated. The test results show that the dynamic component of the shaft friction normalized by a static shaft friction indicates a unique relationship independent of clay type, consolidation pressure and the OCR. Furthermore, the coefficients α and β in the dynamic friction equation introduced by Randolph indicate larger values than those presented by previous reserchers.

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Present paper proposes a topology optimization method of frame structures by using genetic algorithm (GA). In this method, the finite element with a spring having the bending rigidity is used. Through this element, it is possible to deal with trusses, rigid frames as well as semi-rigid frames, simultaneously. The authors have already proposed topology optimization methods fortruss and frame structures, where configurations, size and shape are dealt with as the design variables. In this paper, the connection information is also treated as the design variable, where two methods for expression of connection information are proposed; one is that of direct coding to genetic code and another is the combination method of plural fundamental stable elements. The detail of the proposed methodology is presented as well as the results of numerical examples that clearly show the effectiveness and efficiency of the proposed scheme.

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When installing a mechanical splicing joint in RC members, it may be difficult to secure the bond length of the main bar because of no bond resistance on the surface of a splicing unit. If a joint locates at the member end and is stored in the range of d (= effective depth), it will not become a problem since this range is excluded from the bond length of the main bar in the current design procedure. But it becomes difficult to secure the bond length when a mechanical splicing joint is installed on the intermediate position of a member length, and when it is installed in beam-column joint. In this study a method to include the region of a mechanical splicing joint into bond length was proposed, arranging an intensive shear reinforcement (ISR) at both side of the splicing unit. The mechanism was verified by experiment.

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In this paper, the authors propose a new earthquake response analysis method applying Newmark's β-method and using Fiber-Model. In general, the tangential stiffness of every structural member is necessary for earthquake response analyses, however in the case Fiber-Model is applied to the columns subject to bi-directional moments or variable axial forces, it is impossible to calculate the stiffness. In the proposed method, the equation of equilibrium in Fiber-Model is directly solved by giving the equation of motion as a restricted condition without calculating the tangential stiffness. The authors show its propriety by applying it to a RC column of a single-mass and three-degree-of-freedom system and a 1-span 1-story plane frame.

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The authors propose a method by which to infer the load-deformation characteristics in the ultimate region of PC beams assembled by compressing to columns with round PC tendons. The conclusions are as described below. 1) Under the assumed appropriate deformation conditions, draw out of the PC tendons is computed on the basis of the bond characteristics of PC tendons, and a macro model which enables rotational deformations to be obtained is proposed. 2) the analysis results thus obtained about load-deformation characteristics of beams are in good agreement with the experimental results, and 3) in the aforesaid load-deformation characteristics, strains at extreme fibers of concrete and depth of neutral axis can be estimated with sufficient accuracy.

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This paper describes structural behavior of H-beam to RHS-column connection without diaphragms. The connection is reinforced by increasing thickness of column wall and horizontal haunch of beam flange, in order to assure the required stiffness and strength of the connection. Cyclic loading tests of cruciform sub-assemblage frame were carried out to investigate the stiffness and strength of the non-diaphragm connection. The formulae to estimate the yield strength and ultimate strength of the non-diaphragm connection are developed, based on yield line theory. The formulae give reasonable agreement with test results. The sub-assemblage frame with the non-diaphragm connection has the adequate stiffiness, strength and deformation capacity.

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For developing the high-strength bolted friction joints with the higher slip resistance than the conventional ones, a new friction joint using the plate washers and the main plate with zero hole clearance is proposed here. The external applied load is transmitted by the frictional forces acting on the contact area of the main plate, the lap plates and the plate washers fastened by the bolts. Especially, the frictional resistance between the plate washers and the lap plates is dependent on the bearing resistance of the plate and the shear resistance of the bolt. The static tests of the proposal friction joints with single bolt and the conventional ones are conducted. The slip load, the basic joint behavior and the fracture mode are discussed. And then the relationship between the slip resistance and the thickness of the main plate is investigated.

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This paper presents the method for the prediction of seismic damage on beams and joint panels in steel moment frame. In this method, the maximum and cumulative plastic deformation of beams and joint panels are estimated on condition that input energy into the system is known. The earthquake response analyses of fishbone-shaped frame are carried in order to evaluate the applicability of the proposed method. Comparing the results of the prediction and the analysis, it is found that the results of the prediction are in good agreement with the average of the results of the analysis.

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In this paper, the exposure tests of the new super high tension bolts which have the tensile strength about 1500 N/mm^2 are described and the results of these tests are considered. The new super high tension bolt has the improved thread shape of which elastic stress concentration factor would be reduced to the 60% value of the conventional high tension bolt thread shape. The exposure tests are the accelerated exposure test by Eto's method and the actual exposure tests at four different climatic places in Japan. The exposure tested bolts are the conventional F10T bolt and the new super high tension bolts. And these new super high tension bolts are made from two new materials which have the higher critical diffusible hydrogen contents than that of the conventional F10T bolt.

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This paper is the second of two companion papers on strength evaluation for the joints between steel beams and reinforced concrete columns. Based primarily on the ASCE Guidelines, a new joint strength model was proposed. In the model, the joint was divided into the inner and outer elements. Two failure modes were assumed independently in each element, considering the stress transfer between the elements. From the experimental observations, panel shear and bearing failure modes were considered in the inner element, whereas shear and bond failures were assumed in the outer element. Through a comparison with existing test data, it was shown that the proposed model provided consistent and accurate strength estimates. Some considerations on joint detailing such as tie reinforcement were also provided.

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A number of building damage surveys were carried out for different purposes after the 1995 Hyogoken-Nanbu Earthquake. The damage surveys by local governments intended its use for property tax reduction while the survey by the CPIJ & AIJ group aimed to get technical records. This paper presents building fragility curves based on the CPIJ & AIJ damage survey data for Nada Ward, Kobe City, and the detailed building inventory, structural type and construction period, provided by Kobe City Government. This paper also compares them with the fragility curves based on the local government's survey for property tax reduction to clarify the relationship between the two evaluations.

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The purpose of this paper is to propose a new stiffness design method for shear building subject to a design earthquake with non-monotonic displacement spectrum. The objective function that is a combination of the fundamental natural period which represents 'cost' and the level of maximum displacements which represents 'performance' is introduced into the design method to find a set of story stiffness under response constraints. An inverse problem formulation is used to find the stiffness such that the shear building would exhibit maximum interstory drifts proportional to specified ones. Several design examples and time-history analyses are performed to demonstrate the validity and the accuracy of the proposed design method.

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The hydroelastic response analysis of irregular-shaped large floating structures is formulated by using a discrete hybrid model. The floating structure is discretized by finite elements (FE), whereas fluid domain by boundary elements (BE). Structural analysis is based on the Mindlin plate theory. Only the structure-fluid interface is discretized in the fluid domain. The equation of motion is constructed by coupling BE and FE on the structure-fluid interface. Quadratic isoparametric elements are used for both FE and BE. The accuracy and effectiveness of the BE-FE hybrid model is verified by comparing with published experimental results on the hydroelastic response of a rectangular-shaped large floating structure. Moreover, the dynamic behaviors of irregular-shaped large floating structures are investigated for different wave lengths and incident angles by using the BE-FE hybrid model.

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