The flowability of the fresh concrete is evaluated by the yield value and viscosity. In the previous report, Authors have reported that they have developed the Inclined Flow Test Apparatus and by use of this apparatus analysis were made to obtain quasi-plasticity and quasi-yield points. By analyzing the rheology, it was confirmed that those values were quite similar to the rheology index. In this report, discussion is made with regard to the influence of the mix design of concrete to the rheology index.
This paper indicates adhesive durability of 4 sided structural sealant which was applied to the glass facade for 20 years. Tensile tests about the structural sealant of actual facade were carried out. Results of tensile test were compared with initial data of 20 years ago. The purpose of this study is to ensure the maximum tensile strength and structural properties. Specimen was cut off from the glass unit near the top of the building facade susceptible to wind loads. As a result, most of the specimens reached maximum tensile strength at strain of 50%. All specimens indicated a cohesive failure, also indicated a similar tensile strength compared with the initial value 20 years ago. However, the elongation at maximum tensile strength indicated lower than initial data. Also stiffness was 2 times higher compared to the initial values.
The thickness of fluid-applied polyurethane membrane is mainly affected by the viscosity and application tools. Then, the four levels of viscosity were prepared by changing the adding ratio of diluent from 0 to 10%. Polyurethane membranes were applied on substrate by various trowels and paint rollers. After curing the membrane, thickness was measured at 50mm intervals for all areas of the membrane. Based on the experimental results, the proper combination of diluent ratio and application tool for making a good membrane of having sufficient thickness was proposed.
This paper examined the performance of rust-inhibiting pastes and repair mortars with a calcium-based rust-inhibitor. Polymer-modified pastes and mortars with the rust-inhibitor are prepared as rust-inhibiting pastes and repair mortars. A rebar is treated by the pastes and embedded in the mortars, or a half portion of a rebar embedded in cement mortar is treated and embedded same way. These specimens are cured, and subjected to corrosion test. The corrosion rates of the rebars are evaluated after the test. In conclusion, the paste and mortar with the calcium-based rust-inhibitor may be used as repair materials for reducing repair-induced corrosion.
This paper describes the actual state of surface soiling for the specimen of porcelain tiles with sealing joint. Outdoor exposure test of the specimen inclined 35 degrees against the horizontal level was performed for 15 years. The color distribution of the specimen after 15 years exposure test was measured by an image scanning technique. Reduction of the value of tile surface was increased with the decrease of sealed joint depth from specimen surface. The edge of the tile surface tends to be soiled by dirt deposition. Reduction of the value of the tile specimen with polysulfide sealant was very low compare to the tile specimen with silicone sealant.
Increasing number of high-rise buildings are being equipped with energy absorption devices of elasto-plastic materials. It is important to ensure the safety of these devices to not only under design wind speed but also under cumulative fatigue damage due to wind loading during use. In determining cumulative damage, it is necessary to evaluate the cumulative time of wind speed in a period and the wind response to each wind speed. This paper presents a simple method for evaluating the cumulative time of wind speed in a period and its effectiveness.
This paper describes the dynamic characteristics based on microtremor measurement data concerning a high rise steel building. The object building which was completed in October 1998 is 120 m height and rectangular plan. Microtremor measurement is continued periodically in the building. The acceleration and velocity of measurement data in two horizontal directions and torsional direction are analyzed for natural frequencies and damping ratios on 1st mode to 4th mode. The changes along passages and the dispersions of those dynamic characteristics in microtremor are studied. And the relations between vibration amplitude and damping ratios in free vibration waves employing manpower excitation are discussed.
This paper describes the passive control design performance evaluation method which is considering the influence of the wall viscous damper placement in the high-rise building. The passive control design performance can be evaluated from only two-types of static analysis results without using time history response analysis results. These static analyses can estimate the upper and lower limit of the ratio of the effective deformation as evaluation index of performance. Validity of this evaluation method is demonstrated by comparing with the time history analysis results.
In recent years, it is pointed that the natural period of the buildings varies by the earthquakes or aging degradation. Hence the structural health monitoring (SHM) is developed in order to detect the degradation of the structural seismic performance. The authors have been performing the real-time vibration monitoring by using the new fiber Bragg grating (FBG) accelerometers for 3 years. Based on these, this paper shows the results of vibration monitoring by using the FBG accelerometers. Also it is proposed that the FBG accelerometers can be easily applied to the existing buildings for reasonable SHM.
The force-displacement and the damping-displacement relations of skyscrapers were evaluated from the recorded motions in 20 steel and 14 reinforced-concrete buildings during the main large earthquakes (The 2011 off the Pacific coast of Tohoku Earthquake (Mw9.0), The 1995 Southern Hyogo prefecture earthquake (Mw6.9), the South-east off Kii-peninsula earthquake 2004 (Mw7.5)). Regardless of the earthquakes, the regression curves of the relations to the reinforced-concrete buildings were able to express especially on the basis of the bilinear model of the single-degree-of-freedom system. On the other hand, the degree of the relations to the steel buildings was quite lower than the reinforced-concrete buildings.
This paper describes the system identification of soil-structure interaction system based on earthquake observation data concerning a middle-rise steel building. The object building whose height is 44 m is used for school. Earthquake observations are performed in some stories of the building, ground surface and 30 m below ground. A sway-rocking model is applied for the analysis model. Natural frequencies and damping ratios of 1st mode are analyzed based on microtremors and measured earthquake waves. In analysis of earthquake responses, parameters are story stiffness and damping ratio of this building depending on vibration amplitude levels, and soil impedance.
During the 2011 off the Pacific coast of Tohoku Earthquake, strong motion wave observed at the 30-story reinforced concrete super high-rise building located on poor ground in the Kanto region. By response simulation analysis, a particular response behavior of the building during this earthquake were explored, and then the relationship between damage to building interior and response simulation analysis results were carried out.
A new device is proposed for controlling seismic displacement of a base-isolated building structure by means of a variable oil damper (VOD). This damper provides large damping to reduce the response displacement of the base-isolation layer in severe or extreme seismic events, whereas it provides small damping to reduce the response acceleration of the superstructure in moderate seismic events. Through shaking table tests, it is shown that the VOD can effectively reduce the maximum displacement of the base-isolation layer without increasing the damper force. Comparisons on analytical and experimental results verified the validity of the proposed analysis method.
Based on published reports, data of 65 of seismically isolated buildings about design information and earthquake observation results were collected in the 2011 off the Pacific coast of Tohoku Earthquake. Performance of seismically isolated buildings was investigated. Earthquake motions, responses of accelerations were in the range of 6-756cm/s2. The acceleration responses of superstructures were at most 250cm/s2. The maximum displacement responses of isolator were about 24cm. Cumulative displacements were 100 times as large as maximum displacements.
We propose a new method to estimate maximum story drift angle during a large earthquake using only one accelerometer. The method is based on the assumption that the maximum response is mainly due to low modal components. However, the use of only first two modes was found erroneous. In this paper, we propose adding rigid body motion components in addition to first two modes. Simulation and experiments results confirmed the feasibility of the method.
Seismic reinforcement by Passive Control System is dynamic design, it’s a performance evaluation of buildings due to drift angle. That is why, it is difficult to evaluate with current seismic index of Structure.In this paper, we propose a method for calculating the conversion index that to evaluate the dynamic performance. In addition, considering the correction factor the converted seismic index of Structure. Then, we discuss the relationship between level and the conversion index affected.
Ultimate behavior of Lead Rubber Bearing (LRB) and Natural Rubber Bearing (RB) was investigated by bi-directional loading tests. LRB specimens provided by 7 types small models, which have square and circular shape, varied lead plug diameters, lead plug disposition and rubber layers. RB specimen was provided by square shape without lead plug. In this study it was cleared that brake-shear-strain was not influenced by the cross-section shape, lead plug diameters, and lead plug dispositions. Moreover LRB wasn’t spoiled for brake-shear-strain under the bi-directional loading. It was also found that the brake-shear-strain of LRB was the same as that of RB.
Performance of the super high-rise seismically isolated building during the Great East Japan Earthquake was reported. The response acceleration of the top floor was almost same as that of the 1st floor. The maximum displacement of the isolation devices was 15 cm, and the cumulative displacement was about 10 m. The dynamic response analysis, considered variation of the characteristic of rubber bearing, ambient temperature and so on, was coincident with observed records.
In this paper, two building foundations improved by the grid-form ground improvement method are introduced. The field investigation results of the ground around the building after the 2011 earthquake are presented. The effect of the liquefaction prevention of the grid-form ground improvement ground is discussed based on the dynamic nonlinear analysis for foundation soil layers with an actual acceleration record. Comparing the field investigation result with the simulation analysis, it is concluded that the grid-form ground improvement prevented the liquefaction of the original soil surrounded by the grid-form walls during the 2011 earthquake.
This study is to local fluidization process soil solidifying material cement, water and kneaded, is the content on the development of ground improvement method to build a block-shaped body. Using a bucket mixer was developed to obtain a homogeneous expression intensity. Using the apparatus has been developed and construction management, ensure the timely improvement to a visual representation of the body during construction, to enable constant monitoring. The sampler yet solidified, multiple samples were taken, promptly, to enable the evaluation of compressive strength, improved homogeneity of the whole body.
Pile foundation arranged short piles tend to reduce the shearing force and bending moment of bearing piles by short piles. The authors carried out Static FEM about the steel pipe pile foundation embedded in elastic ground. It turned out that lateral effect of pile group about pile foundation arranged short piles can be denoted by a past estimation method by taking the influence of short piles into consideration. Moreover, comparison of dynamic centrifuge tests and static analysis which imitated these tests showed that estimation method taking the influence of short piles was appropriate in general.
Field construction test of cast-in-place concrete pile using high-strength concrete has been carried out in order to clarify the strength development of high-strength concrete placed with cast-in-place concrete pile construction method. Compressive strength of core specimens sampled from pile concrete was compared with that in full scale model of column using the same concrete mix proportion. The results indicated that the strength development of high-strength concrete constructed under the adequate construction management of cast-in-place concrete pile was very similar to that of high-strength concrete of superstructure.
School gymnasiums are often used as shelter for the neighbors after great earthquakes. For that, fall or damage of outer cladding due to large deformation of the structure must be avoided. In the present study, steel braced frames in longitudinal direction of four real school gymnasiums where the seismic retrofit has been completed are adopted as the structural models. 3D inelastic response analysis is conducted to investigate the correlation between the response story drift or ductility demand of the braces and the seismic performance index Is. Moreover, applicability of the limit strength calculation using simple mass-spring model is verified.
There are traditional wooden buildings supported with overhang which is relatively weaker than the foundation. In this paper, micro-tremor measurement and seismic response analysis for these buildings are performed to grasp their vibration characteristics and seismic performance. From the results of these analysis, their vibration characteristics and the factor to influence their seismic response is examined.
In order to investigate the lateral shear performance of newly developed wooden grid shear wall, full-scale static test by repeated shear loading was carried out. The beam and column members were made of Japanese cedar and the wall was partly reinforced by plywood. As a result, the wall didn’t reach ultimate strength even at 1/7.9(rad) of deformation angle, and it was confirmed that the wall had a high ductility capacity which was derived from plastic rotational embedment resistance of joint parts. The simple evaluation method of the wall was suggested. It was confirmed that the method was appropriate, comparing with the result of the experiment.
A new type brace fastener which fastens the end of a diagonal wood brace to the end of column is developed for Post and Beam construction wooden houses. Since the brace fastener contains high damping rubber, it absorbs a displacement between the end of a wood brace and a column, damage of wood around wood screws is able to be minimized. On static shear loading test, allowable shear strength of a braced wood frame with the new brace fasteners was 4.4kN. From shake table test of a braced wood frame, it was found that a response displacement in the case of the one with the new brace fasteners was conservative in comparison with the case of the one using normal brace fasteners especially under large earthquake motion. Moreover, by means of earthquake response analysis, it was confirmed that the new brace fastener reduces a response displacement under several earthquake motions.
Static shear loading tests on single full-height walls, hanging walls and window-back walls using dry-mud panels were conducted. And then, push-over analysis of combinations of the walls was performed, it was found that summation of shear forces of the single walls is higher than the shear force of combined analysis model except for the range of relatively large deformation. Consequently, to evaluate shear strength of traditional wooden building with dry-mud panel, summation of shear forces of the single walls was found to be adequate.
The static-loading experiments on the improved Nageshi, which has an effect in the antiseismic reinforcement of a traditional wooden structure, are performed. The devised points of the improved Nageshi are the followings. 1) The area in which wood caves is increased. 2) The junction of Nageshi is reinforced with Japanese-type nails. The following knowledge were acquired as the results of the experiment. 1) Strength degradation of Nageshi without a joint is small. 2) Reinforcement with 6-sun Japanese-type nails prevent strength degradation of Nageshi with a joint. 3) An outer column type joint is as strong as the inner column one.
We experimented on the shaking table of the 1/6 scale models of slip hysterisis characteristic that assumes the timber framework construction. And, we experimented the addition of the damper to those models. We summarized the influence of the modulus of eccentricity, the floor stiffness, and the oil damper upon seismic peak response displacement from this shaking table in reference literature (1). This report verified the influence that the modulus of eccentricity, the floor stiffness, and the oil damper exert on the seismic peak response acceleration and the change in the dominant frequency.
In this paper, a new connection for free-form steel structures using FRCC (Fiber-Reinforced Cementitious Composite) is proposed. The connection is an improved version from the previous one proposed by the authors. Firstly, basic material characteristics of FRCC using high strength mortar and two types of steel fibers are investigated through compression and bending tests. Then a full-scale connection composed of the FRCC, stud-welded rebars and shear connectors is constructed and subjected to cyclic bending. It is shown that the connection is capable of transmitting nearly half the bending capacity of the connected steel members. During the test, bond stress distribution of a stud-welded rebar to the FRCC is observed in detail.
Recent super high-rise buildings adopt Fc100 N/mm2 class concrete columns. High-strength concrete columns of Fc150 N/mm2 class are also under development. However, existing studies have identified no sufficient structural properties of high strength columns, so we conducted loading tests to identify such properties. The tests revealed that strength and ductility were 10 to 15 % and 20 to 30 % higher, respectively in reinforced concrete columns with steel fiber jacketing or steel plates jacketing than in conventional columns, and could secure marginal drift angle of R=1/25 rad or higher under high axial forces with 0.5 axial force ratio.
The authors proposed estimation formula of allowable shear strength of R/C beams in consideration of residual shear crack width. However, this formula is not applied to R/C columns. The authors conduct tests of R/C columns using 685N/mm2 shear reinforcement under comparative low axial force. Based on these tests result, the precision of estimated allowable and ultimate shear strength of R/C columns is clarified.
It is important to investigate mechanical properties of concrete in the seismic evaluations. Maximum strength and Young’s modulus of concrete are directly related to the seismic performance of the RC existing buildings. Young’s modulus is concerned with the shear strength of the post-installed anchor bolts used in the retrofitting process. In this paper, the mechanical properties of the concrete from the SRC building constructed 38 years ago were discussed based on the stress strain curves which were obtained from the compressive tests.
In order to verify the performance of a seismic retrofit method that connects additional slabs with outerfreme installed damping system to the existing building, dynamic loading tests were conducted. For the form of retrofit, whether or not the additional slabs have sufficient stress transfer capacity is important. In this study, the stress transfer capacity of slabs were verified. As a result, it was verified that the stress transfer capacity remained intact and that the damping system were effective for controlling vibrations. It was also found that an evaluation model considering additional slabs could appropriately evaluate the results of tests.
Under the 2011 Tohoku earthquake, many buildings were suffered by strong ground motion and tsunami. A total of 216 of damaged steel buildings of public educational institutes including 147 of gymnasiums were investigated from April to June 2011 by AIJ. In this paper, correspondences between seismic damage of steel school buildings and the ground transformation are reported.
According to the past researches, the structural damage of high-rise steel building when subjected to long-period ground motions is characterized by the concentration of deformation to beam-column connections. In addition, it is known the field weld connection details tend to have poor deformation capacity. So far, there is no comprehensive data base about beam-column connection details of existing high-rise buildings. This study provides a data base of high-rise steel buildings, focusing on the beam-column connection details.
A reconnaissance of steel school buildings and gymnasiums damaged by the 2011 Tohoku earthquake has been conducted by the Architectural Institute of Japan. This paper focuses on seismic damage to column bases and roof joints. In pre-1982 buildings, early fracture of vertical brace connections tended to reduce damage of column bases. Although the design procedure of brace connections was improved in 1981, it was not till 1995 that the procedure for column bases was revised. Therefore, in post-1982 pre-1995 buildings, the relatively strong brace connections tend to induce severe damage to column bases.
This paper proposes a new out-of-plane loading system for masonry walls. Uniform distributed loads are applied to masonry walls by a rubber airbag. The test system was developed aiming at obtaining basic mechanical characteristics of simply supported masonry walls in the out-of-plane direction. In this study, two kinds of structural tests were conducted (a) to verify the developed loading system by using an aluminum plate specimen, and (b) to evaluate the out-of-plane performance of a brick wall specimen. Consequently, the test results clarified (a) good agreements between the experimental measurements and theoretical estimations, and (b) vulnerability of the brick wall.
With regard to fire protection for exterior walls of a building, only ‘fire-resistive performance’ is considered, according to the current building standard law of Japan. In previous studies of authors, new test method for evaluation of fire propagation along combustible cladding, was proposed, using primarily test specimens of facade wall with exterior thermal insulation without vent layer. In this paper, newly made results of facade fire tests with other specimens of combustible facades, such as sandwich panels, photovoltaic sheets, combustible coating materials, and exterior insulation with vent layer etc. are discussed.
Mobility of the patients and number of ward staff available for disaster management in hospital ward are investigated in a large comprehensive hospital in Tokyo consisting of 1020 beds using the physical records of respective patients. The mobility ratios show high daily fluctuation, weak seasonal change and strong dependence on medical departments. Most of patients in pediatrics system, psychiatry, and cranial nerve need assisted evacuation at the event of fire. The investigation has revealed restriction of the number of ward staff at night, which may need extensive reorganization of emergency management.
When flame penetration occurs at the glass window opening located in the exterior wall after flashover happens in the room/compartment where fire originally breaks out, exterior surface of the facade wall is heated by convection and radiation produced from the flame and plume spouted out from the broken window. ISO 13785-2 “Reaction-to-fire tests for facades – Part2: Large-scale test,” prescribes the test method determining the fire performance of exterior material installed onto the outer wall when heated by the external flame from the broken window. In this study, applying the large-scale fire test apparatus of ISO 13785-2, temperature and heat flux were measured in the proximity of non-combustible exterior facade which is located above the window opening from where flame spouts.
This paper describes the development of passive reduction of heavy-weight floor impact sounds by tuned mass dampers set at ceiling. Experiment was carried out with ceiling of the specification of general multiple dwelling houses. By using the tuned mass dampers composed of a viscoelastic body and a 50mm steel cube, the vibration acceleration level of the ceiling was decreased by 12dB. As a result, heavy-weight floor impact sounds level was decreased by 4-5dB.
An enclosed demolition method with the roof for a high-rise building can reduce the noise propagation to the neighborhood in comparison with a conventional demolition method without the roof. In order to grasp and predict the noise propagation, various measurements and numerical analysis by extended energy integral equations were performed. By comparing the measurement results and analysis results, prediction accuracy was verified. Noise propagations of an enclosed demolition method and a conventional demolition method were compared by analysis.
The purpose of this study is to clarify the tendency to the reduction of heavy-weight floor impact sound of the floating floor by difference of the section specifications change. The floating floors were constructed in a box frame-type reinforced concrete construction which regulated in JIS A 1440-2, the reduction of transmitted heavy-weight floor impact sound levels were measured. From above results, the relationship between the section specification and the performances of them was examined. Moreover, the correspondence of two heavy/soft impact sources, a car-tire source and a rubber ball source, was investigated.
In this paper, we examined the distribution of sound pressure level of the air layer of the dry double floor using the finite element method. Impact source was used the impact force characteristics (1) of JIS A 1418-2. Distribution of sound pressure level of the floor of the air layer was under the influence of the vibration characteristics of the slab. Air layer under the floor was considered measurement point, and is compressed by bending wave of the slab around the measurement point.
Environmental vibration impact on humans in buildings is caused by ground-borne vibration due to rail transit systems, road traffic, construction sites, and industrial plants. To estimate the effect of vibration on humans, it is necessary to measure the tri-axial vibrations in the vertical and horizontal directions in buildings specified in the standards regulated by ISO2631-2:2003. Vibrations in two- and three-story detached houses of wooden or steel construction were measured. The vibration amplifications caused by building structural resonance were evaluated as ratios and level differences in 1/3 octave band vibration accelerations measured at ground near substructure and floors in the 120 houses vibration measurements.
The photovoltaics applied to the exterior wall of buildings is one of the elemental technologies of Net-zero Energy Buildings. The purpose of this study is to acquire the amount of solar radiation and power generation in eight vertical exterior wall sides, such as south, south-west, west, north-west, north, north-east, east and south-east directions, and to clarify the rate at the time of comparing with the horizontal surface or a 30-degree south slope. The observation system installed on the roof top of the building which locates in Hakusan-shi, Ishikawa prefecture is used for observation.
PMV control system was applied for a ceiling radiation cooling/heating system utilizing groundwater as heat source/sink. Evaluation was based on the three season measurements of summer operation. The research results are summarized below: 1) Indoor PMV values were settled in the range of 0-1. 2) As compared with room temperature control, PMV values in the room under PMV control became low about 0.2. 3) The hunching phenomenon at night was canceled. 4) In PMV control, almost same indoor thermal environment was realized by the case which put the control position on the wall, and the case which placed the control position in the center of the room.
The subject of this paper is the heat source system with the Ground Source Heat Pump(GSHP) system in the PHC foundation piles. The thermal storage characteristics of the ground may be used to improve the GSHP system performance in this hospital by alternating the storing and restoring cycle on day-night basis in the summer season. The analysis during the commissioning shows the effectiveness of the GSHP system concept and improved system performance as a result of changing the operational condition.
In this study, we model the estimation of the CO2 balance throughout the life cycle of construction timber. We study about construction utilization period considering forest-growth and show the long-term estimate of the emission reduction effect. As a result, it was found that CO2 balance become plus (absorption) using Japanese cedar and cypress in Kochi Prefecture more than 50 years as construction timber. Moreover, as a result of long-term estimate, we show emission reduction effect by increasing the construction timber volume and extending the utilization period.