The workability of high strength concrete with specified design strength of 150MPa and its strength development in RC columns were investigated, and the following results were obtained. (1) Strength in structure of columns placed in both summer and winter were more than 170MPa (2) The strength at the outer part in the columns placed in winter was similar to that of the center of the same columns. (3) The strength development of core specimens of the upper part of the RC column was similar to that of the lower part of the same column, and no segregation of the course aggregate was seen.
For the purpose of evaluating critical differential movements between ceramic tile finishings and concrete bodies, various thickness of mortar layers bonded on concrete were experimented herein. As a result, in the all cases of various thickness, ceramic tile finishings were exfoliated on the interface between the both materials. The exfoliation differential strain and critical movements were evaluated on addition of potential deformation of finishings are clarified.
A high-strength concrete with silica fume was placed in the full-scale model column specimens and temperature histories and core compressive strengths were determined. Laboratory-scale specimens were prepared with the same concrete and their temperature histories and compressive strengths were compared with those of model columns. Effects of testing parameters, such as the number of specimen in an adiabatic curing chamber, thickness of thermal insulation of specimen jacket and the duration of curing, on the temperature history and compressive strength were discussed. The effects of the number of specimen in a chamber and the thickness of insulation on the maximum temperature and temperature increasing rate were found to be significant but insensitive to 28 and 91-day compressive strengths.
Recently, method of construction using half precast concrete technique has come to public notice. But it is necessary to confirm the uniformity in the process of execution and the uniformity of structural members as finished products. In this paper, bending test results of beams are discussed for test specimens manufactured by technique of half precast concrete and in-situ concrete based on the following five measured items; 1) Relation of load-deflection and bending moment-curvature, 2) Relation of load-strain of reinforcing bars and at surface of test specimens, 3) Failure state, 4) Total width of bending cracks and 5) Electric resistance of carbon censers built in test specimens. As the results of comparison, it is obtained that the parts of precast concrete form and in-situ concrete behave almost uniformly until the ultimate state. And also, structural property of the test specimens manufactured by technique of half precast concrete is very similar to the test specimens manufactured by in-situ concrete technique.
The wind resistivity of waterproofing roof made of stainless steel membrane as well as the effect due to displacement of clips has been analyzed by using an apprximate analytical solution conducted by the author, and an evaluation on the solution was made in comparison with the result of durability test and FEM. As a result, it is verified that the solution can duly be applied. As the peal strength of stainless steel membrane measured by the test is 0.387kgf/mm when the wind pressure is 600kgf/m^2, it is confirmed that this waterproofing roof is sufficiently durable. From the result of this study, the analytical solution can easily be obtained and it hopefully provides a reliable waterproofing roof.
The world's biggest coal silos, with a total storage capacity of 100,000 tons of coal, are now being built for Maizuru Power Plant on Ohurapeninsula, Maizuru, Kyoto. This power plant is owned by The Kansai Electric Power Co., Inc. Prestressed concrete structure was adapted to withstand pressure by stored coal. Dynamic analyses considering interaction between the coal and the prestresed concrete silo were carried out as part of the seismic design. A new construction system called the "slip-up system", was developed as part of the project. This system uses an auto-climbing roof framing structure mounted on the slip form system. It reduces the amount of temporary support required, the cost and the construction time.
This study aims to develop a simple and easy joint method of PCa-CFT. First, thermal transition of steel tube and concrete in full-scale models, which are column joint part and column-beam joint part of PCa-CFT, is measured after field welding under nearly actual construction condition. Secondly, thermal analysis method is verified in comparison with the result in full-scale model of column joint part.
The purpose of this study is establishing the objective-based durability design method for building components. Herein the objective-based design means that selecting the most appropriate specification of building components according to the each requested performance level of durability. In this paper, it is reported the attitude survey on durability of RC building components for building engineers. According to the results, the most engineers consider that it should be selected the appropriate specification of building components according to the conditions such as region, direction, parts of buildings.
The Housing Secure Law was executed and it is possible to indicate durability grade of buildings. However, in the case of masonry buildings, only one type of masonry structure, that is Reinforced Hollow Unit Concrete Masonry Structure, can be applicable to the law. In this paper, an estimation method for durability grade applicable to all-type reinforced masonry buildings is proposed. The estimation method is fundamental to that of reinforced concrete structure of the Housing Secure Law, and concept of effective cover thickness, countermeasure for ram water and so on are added. And investigations of the method were earned out in the committee concerning about the Housing Secure Law.
A new prediction method for frost deteriorations of reinforced concrete buildings using equivalent cycles to the ASTM test is proposed. In the method, severity of the freezing and thawing is expressed by the equivalent cycles to the ASTM test. The equivalent cycles to the ASTM test for some members of buildings means that the members receive same deterioration as cycles of freezing and thawing test of ASTM C666 A method. Effects of curing conditions and freezing conditions and so on are determined by results of data analyses of freezing and thawing tests. The equivalent cycles to the ASTM test for regions are determined by the extremal value of minimum temperature of the region, and the result is achieved by exposure tests and analyses of weather data. An easy method for determining the regional condition using the post code and altitude is proposed.
An easy service life design method for frost deterioration of reinforced buildings is proposed. The design method consists of the geografic division and the countermeasure which is determined in parallel with the geografic division. The countermeasure has three levels, that is "a. none", "b. restriction of material and mix proportion + reservation of air content" and "c. b + ingenuity of detail design". The geografic division is determined considering about severe part of buildings using the concept of equivalent cycles to ASTM freezing and thawing test. At the last analysis, the geografic division has three zones, that is "A. not lower than -2℃", "B. not lower than -5℃ and lower than -2℃" and "C. lower than -5℃".
The purpose of this study is to clarify the present state of the art on recycling of finishing material wastes derived from production process, construction work and demolition work. The survey was conducted by interviewing and sending questionnaires to manufacturer associations of the finishing materials. The survey was carried out from July 2001 to March 2002, and the current situations and problems were identified and discussed.
Snow falling off roofs of houses in cities and towns in snowy regions often causes problems with neighbors and injuries or even deaths. One solution for such problems and accidents is to use snow guards on sloped roofs to prevent the sliding of snow. Experiments were carried out in this study on the strengths of snow guards and spacing between snow guards on a sloped roof. The following results were obtained. 1) The smallest value of the coefficient of friction should be used for calculating the number of necessary snow guards. The coefficient of friction between the roofing material and snow on the roof is smallest in the case of wet granular snow. The results of an experiment showed that a coefficient of friction of less than 0.1 should be used for calculating the number of necessary snow guards. 2) The results of an experiment on strengths of snow guards showed that there was a difference of about two fold between the weakest and strongest snow guards, indicating that the strength of snow guards should be considered when determining the number of snow guards to be used on a roof. 3) Snow guards should be attached at intervals that will prevent creeping of the snow between snow guards. Creeping of snow on a sloped roof occurs more easily the thinner the layer of snow is. The results of an experiment carried out on roofs with gradients of 21.8-30.9 degrees showed that snow guards must be attached to the roof at intervals of less than 680 mm in order to prevent creeping of a snow layer of 10 cm in thickness.
The primary purpose of this study is to provide simple formulas for estimating the design wind loads for the structural frames of rectangular flat roofs considering the dynamic response to turbulent wind forces. Two types of structural systems are considered here ; that is, (i) a series of simple beams arranged in parallel, and (ii) a structurally integrated type, which acts like an elastic plate, such as space truss. The characteristics of the first modal force are investigated, using a model of the pressure field on the roof. Based on the results, the gust effect factors for estimating the design wind loads are formulated as a function of the geometric and structural parameters of the roof and the turbulence intensity of approach flow. The formulas are verified by comparing the results on the load effects predicted by the formulas with those computed by using the experimental results for the modal force. The results of this study will be used for updating the specifications of roof wind loads in the AIJ Recommendations for Loads on Buildings.
Near-fault strong motions from the asperity model are evaluated by the Kamae and Irikura's (KM) and Takemura and Ikeura's (TI) method. KM explicitly considers the asperity, whereas TI assumes uniform heterogeneity on the fault. In the period range shorter than 1 sec, both methods give the same amplitude of response spectra. On the contrary, remarkable difference can be found at the predominant period of 2 sec, in particular, in the direction of rupture propagation. This difference is attributed to the rupture directivity effect caused by the asperity. It is crutial to understand the difference when the stochastic methods are applied to the prediction of strong motions.
The mobile shaking table named BURURU is developed for the use of teaching dynamics in classroom. The shaking table and many kinds of experiment models are packed in a suitcase. The weight of case is about 10kg. BURURU uses the mechanism to transform the rotational movement to translational movement. The table vibrates harmonically when rotating the handle in front of the case. The prepared experimental models are the lumped mass model, two story frame structure where the roof, walls and braces are easily put on and taken off, the base isolation system, the tuned mass and liquid damper, the friction damper, the soft soil model and the liquefaction soil model. The students easily understand the dynamic phenomena of structure and soil through the combination of formulation, graph, animation of simulation analysis and the experiments using BURURU.
The Building Standard Law was revised and the calculation method of response and limit strength was enforced. This paper shows characteristics of the method on required strength for pre-given ductility factor through the comparison with time history response results, and the effects of soil structure interaction are examined as well.
This paper discusses a retrofitting method with two damper systems for the traditional wooden structure built two hundreds years ago. One of the systems is the frictional wall damper system named as "Kame-Kabe", the which energy absorption mechanism is making use of friction force between wooden members. The other is pretensioning toggle damper system, which is consists of steel rods, oil dampers and coil springs. In order to reduce compression forces on toggle members, pretensioning system by using coil springs is adopted. The paper shows that this retorofitted structure has high performance against the earthquake by computing elasto-plastic response simulation.
The characteristics of the structural frequency and damping as well as the vibration due to the wind forces of a tower supported steel stack are studied in long period field observations. And also the correlations of the vibration due to the vortex between the field observations and wind tunnel tests using 3-D rocking model are discussed. The results are summarized as follows ; 1) the vibration due to the vortex obtains y/d=0.12 for h=0.33% and y/d=0.006 for h=0.89%, respectively (y is the maximum amplitude at the tower top, d is the duct diameter of the stack, h is the damping ratio), 2) the gust responses due to strong winds are studied by the strain data at the half of the stack height, 3) the correlation of the vibration amplitude with the field observations and the wind tunnel tests based on the Scruton number is discussed.
For the purpose of understanding vibration of stadium stand due to group jumping while watching sports, the authors performed 32 persons jumping test for the actual steel framing stand and measured displacement of the stand structure. And moreover we analyzed and examined the dynamic force and the response of stand structure. Consequently, in case of substituting the static force for jumping dynamic force, static force should be 1.5 times of dynamic force in case of 32 jumping persons. Based on this result, it seems 1.3 times in case of 100 persons jumping. The relation between the number of jumping persons and the response is linear logarithmically. Therefore we can predict the response of the stand structure in case of full spectators jumping as well.
The new seismic-free system (SFS21) is developed under the concept of longevity and earthquake-proof design of buildings. This system consists of two parts. One is the RC core-shaft on top of which a seismic-free mechanism composed of double-layered rubber bearings is installed. The other is the office or residential space hanging from the hat-truss. In this paper, we describe the main concept of SFS21 and the results of analytical studies, static loading tests and shaking table tests. The shaking table tests use a 3-dimentional 1/16-scale model which employs double-layered rubber bearings and concrete weight. Both of the static loading tests and the shaking table tests show that SFS21 system behaves as intended. The response of the system can be predicted closely by using the analytical model shown in the paper.
Reaction control device was developed for the hybrid foundation consisting of a mat foundation and a small number of complementary bearing piles. The device allows a pile to retain its acceptable maximum axial force through friction mechanism even if the building subsides due to consolidation of the subsoil. The device is configured by internal pipe, slit pipe and external pipe. The slit pipe is deformed and contacted with the external pipe to create friction force by pressurizing oil. The relationships among friction force, sliding displacement and oil pressure have been measured to evaluate the coefficient of friction.
The characteristic of bearing capacity of the enlarged basement piles and the buried piles installed by different construction methods are discussed. The point bearing capacities of inner excavation piles, pre-boring piles and the fabric bulb piles were compared. And as the conclusion, it was found that the bearing capacity of the fabric bulb pile has N value accordance property and the variance of the point capacity is smaller than the other piles.
The purpose of this study is to collect measurement data on a tensegric truss arch installed at Nihon University and to clarify the damping ratio of the arch for making clear the characteristics of damping of shell and spatial structures. Damping ratio experiments were conducted by three methods i.e. exerting impact, rope-cut and microtremor response and analyzed the data by these experiments at first vibration mode, respectively. Further, rope-cut experiments were carried out in order to examine displacement amplitude dependence of damping by using weights from 10kgf to 100kgf at 10kgf interval.
The main objective of this research is to investigate the dynamic properties of a full scale model of tension truss dome. Vibration tests and Wave propagation tests of the tension truss dome used as an annex on the former institute building of I.I.S., the University of Tokyo, were performed. In this paper, outline of the vibration tests and the test results of each model are shown. The results snow the influence of the existence of membrane, the stiffness, yield members, etc., for the dynamic properties of a lightweight frame structure.
The research and development of hybrid structures cannot be referred as one with sufficiently actual results. In this report we suggested the wooden HP shells made by lumbers of two layers by which the direction lies at right angles with the lugscrew bolt. Here, an aramid fiber sheet is introduced into four wooden HP shells so that the intensity and rigidity of the shells are strengthened. This hybrid structure further combined with steel string beam structure is applied to Yamadera Post Office in Yamagata Prefecture.
As for the traditional wooden house, the performance which is excellent because structural behavior at the time of the earthquake isn't made clear fully isn't reflected on the structural design. It is important to calculate the characteristic period of the traditional wooden house to make action in the earthquake clear. The purpose of this research is the proposal of the method which the characteristic period is estimated at simply.
This is a technical report for the development of slab including L-shaped void, which is compensating the faults by not only 1 way void slab but also 2 way one. In this study, we report the primary rigidity, yielding rigidity, and the shape of crack in this loading condition. This construction has two characteristics. One is mitigating the degree of anisotropy by using the slab with L-shaped void tube. Two is simplifying the design for slabs by regularly arranging the unit of tube.
This report introduces a new structural design method for over-track low-rise buildings without footing beams. We investigated the structural performance of existing over-track buildings, and grasped the seismic response and load-carrying capacity of a number of building models by analytical studies. The results were reflected in the revision of "Standard for Structural Design of Over-Track Low-Rise Buildings." In the new design method, the push-over analysis of soil-structure interaction models are used, and the seismic performance of buildings is made clear. As a result, it is possible to construct a building without footing beams both perpendicular and parallel to tracks.
Constructing additional retrofitting walls in open frame can effectively enhance seismic resistance of structures. In retrofitting, the additional wall can be assembled with small pieces of precast concrete panel. The authors investigated a new retrofitting method with this assembled wall. To complete this new method, this study conducted horizontal loading test with half scale assembled wall elements. The loading tests with the assembled walls revealed that these walls have comparable load resistance with ordinary reinforced concrete wall and higher deformation ability. Furthermore, it was found that modifying frame-panel or panel-panel connection enables one to control load resistance and deformation ability of the assembled walls.
Seismic hybrid isolation system using sliding bearings and multi laminated rubber bearings is one of the practical isolation devices, because it can make the primary period of horizontal responses comparatively long easily, not changing that of vertical responses. However, there have been few studies on frequency characteristics of structure with this hybrid isolation system, which is important for seismic design of equipments and/or piping system attached to the structure. This paper shows that we can evaluate frequency characteristics of structure with the hybrid isolation system well, through the simulation analyses for results of shaking table excitation test.
Recently it has been necessary that designers state structural performance to customers. In this paper, it is reported that we developed the method of design, based on limit state design, that can be used for presentation of structural performance, for customers understand structural performance. In the method of design, structural performance is evaluated quantitatively by crack width. And we developed presentation tool for performance statement and cost evaluation to design by dialogue with customers.
This paper reports on two reinforcement methods we have developed from a new perspective : one is "redundant member attachment method" which can be useful in the main post near cross-arms, and the other is "parallel member attachment method" in which reinforcement materials utilizing high rigidity of flange joints of the steel-tube main post are attached to the transmission tower. These methods, without a need for on-site welding and material processing, enables quick assembly. As a result, the construction can take significantly short time compared with the conventional methods. The authors have studied some reinforcement effects of these new methods by the compression test of actual models. And it has been found that most of the ultimate strength can be estimated by a nonlinear three dimensional analysis using FEM software. In addition, with regard to the impact on dynamic characteristics of the steel tower, we have conducted a comparative study of vibration test before and after the reinforcement was applied. Based on the results, the reinforcement effects on the vibration modes and the damping characteristics of the towers were confirmed.
The objective of this study is to identify the rate of reduction in radiated heat by fire protection equipment using a water curtain such as drencher system. A fire test was conducted while assuming the fully developed fire. Test equipment consisting of a heating furnace and a drencher was used. Data were obtained on the relationship between the intensity of radiated heat and the temperature in the furnace while the drencher was active. The test results were used to identify the rates of reduction in radiated heat for respective water curtains created by different water shooting system, the relationship between the quantity of discharged water and the radiated heat reduction rate, and the methods for applying the radiated heat reduction rates in building fire safety design
The purpose of this experiment is to grasp the efficiency of the heat prevention of the drencher that is used as the compartmentalization in a building. We prepared the two types of specimen that has the different size of opening. The both position of the drencher head and the amount of discharged water are treated as the parameters. And the specimen is heated under the condition of water curtain. We observed the following tendencies ; 1) If the both heat temperature and the drencher's dram are fixed, the measured temperature of non-heated wall side is fixed. 2) The efficiency of heat radiation prevention becomes higher depending on the amount of discharged water increasing.
A case study was carried out on fire safety design of a high-rise hotel building. Safety checking was made on evacuation safety, firefighters' accessibility and structural fire resistance. The whole building was split into fire and smoke compartments. Their integrity was checked against design fires, which consist of fully developed, localized and choked fires. Then each performance criteria was checked against established fire and smoke spread assumptions. New proposals of design strategy are ; introduction of choked fires for concealed spaces ; consideration of smoke compartmentation and staff response during horizontal zoned evacuation ; and design for thermal environment in fire fighting bases.
A case study was carried out on fire safety design of an open-type car park building. Safety checking was made on evacuation safety, fire fighters' accessibility and structural fire resistance. The design fire was assumed by a successive burning of cars in one row. The fire and smoke were confined within less than quarter of one floor area. By using this benefit, temporal refuge area (TRA) and fire fighting base (FFB) were arranged. Safety of occupants and fire fighters were assessed against fire scenario. The structural frame was constructed by unprotected steel frame, whose stability was assessed by simple plastic theory.
Edo recurrently suffered with numerous big fires. However, there were few documents, recording the numbers of deaths and sizes of burned areas caused by those fires. We examined the document of fires occurred within Edo area on "Edo Saigai Nenpyo". And we invented the method to estimate the size of fire from the document. We chose 19 cases that the numbers of deaths have been shown in the document and we investigated the relations between the numbers of deaths and the sizes of fires. It became clear that the frequency of big fires during the last half of the Edo Period was different with that of the first half.
Scatter of firebrands caused by a fire is numerically simulated by means of CFD (Computational Fluid Dynamics) based on a turbulent model. The results are compared with an investigation by the authors on the distribution of firebrands and spot fires due to a hotel fire occurred in Shirahama, Wakayama prefecture on November 17th 1998 by exploration and questionnaire. New Technique concerning motion of a flying firebrand is included in the model, and scatter of them can be predicted realistically in comparison with the former method by the authors.
Fire of an approximately 1,000m^2 wooden gymnasium is investigated with the interest in the verification of the fire safety design for heavy timber construction based on the insulation effect of char layer and in the mechanism of the fast fire spread from the activation of fire alarm to flashover. The conventional char layer growing velocity, 0.6mm/min, is supported from investigation of the remaining components. The fast fire spread is attributed to the full burning of the partition wall.
In the present paper the application of the diffusion index method to beam-slabs is discussed. Through numerical calculation study (FEM), it is confirmed that both a resonance of the slab vibration and a restraining effect by slab-ends can be dealt with in the same manner as the flat-plate slabs. The calculated results of heaby-type floor impact sound by this method agree with the measured results. Thus, this method can be use widely for a prediction of the floor impact sound of architectural slabs.
This text is a report of the result of examining the measuring method of the impedance in the impact time. The change in the impact power characteristic and the influence of the reflection wave were examined by using the signal processing. The ratio that the reflection wave influences increases when the impact time becomes long. And, the difference between the calculation value and the measurement value increases. Next, the relation between the impedance change and the impact power characteristic was examined. The impedance change does not influence the impact power characteristic.
When the residence when the house is bought is selected, the largest element is a plan. Therefore, a new construction method and the design plan are proposed. To relate to the floor impact sound by heavy source is : 1. Out frame construction method. 2. The design that beam depth is equal to slab thickness. 3. Well. Impedance was measured in the multiple dwelling houses where these had been designed. It is clear that the exterior wall influences the floor impact sound by heavy source in the out frame construction method.