Architectural Institute Of Japan Research Articles

Experimental Investigation and Numerical Analysis of the Axial Load Capacity of Circular Concrete-Filled Tubular Columns

This paper focuses on the experimental investigation of the axial load capacity of CFT (concrete-filled steel tube) columns under actual construction conditions during building reconstruction. A total of four samples were loaded up to failure. The varied parameters were the column length and absence/presence of the concrete infill within the steel tube. Further, the analysis is extended to developing a numerical model in the finite element-based software ABAQUS version 6.9. This numerical model includes material and geometrical nonlinearities and was validated with the experimental results. The contribution of the concrete core to the column capacity and the concrete core confinement effect are discussed. Finally, the column capacity was calculated according to several design codes: the Eurocode 4 with and without considering the confinement effect, American specifications, Australian standards, the American Institute of Steel Construction, and the Architectural Institute of Japan. The Eurocode 4 considering the confinement effect provides the closest results to those obtained in the tests.

Study on the correspondence between vibration level and vibration evaluation by residents in real houses through one day

In recent years, the issue of environmental vibration has been much discussed due to the diversification of lifestyles and the increasing of habitation performance by residents. Prolonged exposure to vibration can have psychological and physiological effects on residents and may cause complaints. The current vibration evaluation standard for buildings in Japan is used in the "Standard for the Evaluation of Habitability to Building Vibration" by Architectural Institute of Japan (AIJ). The evaluation scale in that standard is also based on the results of short-time vibration evaluation experiments in laboratories. However, this evaluation scale is considered to be different from the vibration evaluation perceived by residents in their daily lives. Therefore, in this study, we researched for the purpose of the evaluation of vibration sensation in long-term daily life. In this paper, we measured vibration through one day in real houses. And we considered the correspondence between vibration levels and residents vibration evaluation.

An investigation of the contribution of vibration duration on subjective response to horizontal building vibration

As an evaluation method for evaluating the habitability to building vibration, the ISO 2031 series of international standards defines the VDV for transient vibration, in which the vibration duration is considered by time integration. The evaluation method for non-stationary-like vibrations in the guidelines for the evaluation of habitability to building vibration of the Architectural Institute of Japan (AIJ) also specifies a method to consider the effect of vibration duration on the evaluation. In this paper, laboratory experiments using an electrodynamic shaker were conducted to investigate the relationship between the subjective response regarding occupant habitability and the horizontal vibration of buildings caused by external vibration sources such as road traffic and railways. Binomial logistic regression analysis was used to quantify the effects of acceleration magnitude and vibration duration on the exposure-response relationship. The comparison of models with different proportions of occurrence (cutoff values) of subjective responses showed different effects of acceleration magnitude and vibration duration.

Shear strength behavior of high-strength fly ash concrete beams with low-bond reinforcement

This study aims to investigate the shear behavior of high-strength fly ash (HSFA) concrete beams with low-bond reinforcement (LBR). With this purpose, twenty-three HSFA concrete beam specimens were constructed and tested. The experimental results showed that owing to the high-strength property of LBR, the tested beams easily failed in shear. The shear strength of the HSFA beams was mainly controlled by the shear span to depth ratio (a/d) and transverse reinforcement ratio. The shear strength Vs carried by the transverse reinforcement started to increase when the shear strength Vc carried by the concrete started reducing or growing at a lower rate. Formulas in design provisions, except for strut-and-tie model (STM) and those in the “AIJ standard for structural calculation of reinforced concrete structures” proposed by Architectural Institute of Japan (AIJ), could not accurately assess the shear strength of HSFA concrete beams because they do not reasonably consider the effect of a/d on the Vc. Generally, the current design models underestimate the Vs. Based on the test results, a new model that can reasonably consider the effect of a/d on Vc was proposed to accurately evaluate the shear strength of HSFA concrete beams reinforced by LBRs. This study deepens the understanding of researchers and engineers of the shear behavior of HSFA concrete beams with LBRs.

Modified ultimate bearing capacity formula of strip footing on sandy soils considering strength non-linearity depending on stress level

Most of the contemporary ultimate bearing capacity (UBC) formulas assume a linear yield function in shear stress-normal stress space. However, experimental investigations have corroborated the non-linearity in the failure envelopes of sandy soils. This study focused on the assessment of the stress level effect on the UBC of surface strip footings ascribed to the soil unit weight (γ), footing size (B), and uniform surcharge load (q). The rigid plastic finite element method (RPFEM) was employed for the analysis. The analysis method was validated against the centrifuge test results from the published references in the case of various sandy soils with different relative densities. The RPFEM, using the mean confining stress dependence property of Toyoura sand, is utilized in non-linear finite element analysis of model sandy soil. The normalized ground failure domains in the case of the non-linear shear strength model are gleaned smaller than those in the case of the linear shear strength one. The numerical results are compared with the guidelines of the Architectural Institute of Japan (AIJ) and the Japan Road Association (JRA). The modification coefficients are ascertained for the frictional bearing capacity factor (Nγ) and surcharge bearing capacity factor (Nq), and a modified UBC formula is proposed. The performance of the proposed UBC formula is examined against the analysis results and various prevailing UBC guidelines.

Centrifuge test of non-linear soil–pile response using 1:50 scale reinforced concrete pile

This study aimed to clarify the highly non-linear behaviour of a soil–pile system and proposes a small-scale reinforced concrete (RC) pile model for use in centrifugal tests. Horizontal static loading centrifugal tests were conducted on 13 small-scale RC pile models at 50g centrifuge acceleration to illustrate the reproducibility of a full-scale RC pile. The experimental results show that the maximum flexural strength of a small-scale RC pile can be estimated accurately as a function of the full plastic moment Mu. The current design formula for the maximum shear strength Qs in the Architectural Institute of Japan (AIJ) standard is applied to full-scale RC members, while the final fracture mode of the proposed small-scale model corresponds to its estimation. Horizontal static loading centrifugal tests were conducted on a soil–pile system consisting of dry sand and a small-scale RC pile model. Furthermore, the experimental results for the soil–pile system correspond well to the ultimate strength for flexural fracture proposed by Broms and that for shear fracture according to the AIJ standard. The experimental results obtained in this study for the proposed small-scale RC pile model are valid for use in assessing a soil–pile system's maximum strength and final fracture mode.

PIGNN-CFD: A physics-informed graph neural network for rapid predicting urban wind field defined on unstructured mesh

Urban wind field plays an important role in quantitative assessment of urban environment. Compared to field measurement and wind tunnel experiment, Computational Fluid Dynamics (CFD) simulation having the advantages of low cost, repeatability and reliable precision is becoming a common scheme to model flow field of one fixed urban scenario, but still faces the problems of time-consuming computation and lack of scalability for practical engineering application. This paper proposes PIGNN-CFD, a novel physics-informed graph neural network for rapid predicting urban wind field based on irregular unstructured mesh data of CFD simulation. Specifically, a CFD model employing the unsteady Reynolds-Averaged Navier-Stokes (RANS) equations with the standard k-ε turbulence model, is constructed and then numerically solved by OpenFOAM to simulate urban wind field defined on unstructured mesh. After being validated by publicly available wind tunnel test data provided by the Architectural Institute of Japan (AIJ), the proposed CFD model is employed to build the training and test sample sets of urban wind fields by simulating the wind blowing through various randomly generated small-scale urban scenes. A novel physics-informed graph neural network, both approximating the training data and automatically satisfying the RANS equations, is designed and trained to perform wind field inference on unstructured mesh graph, and then scaled up to predict wind fields of arbitrary large-scale urban scenes. The predicted wind field results of two urban environments at different scales show that the well-generalized PIGNN-CFD model runs 1–2 orders of magnitude faster than the CFD model on which it is trained, while obtaining the consistent computational accuracy.

Planning Theory for Sustainable Community Resettlement and Environmental Transfer in the Context of Natural Disaster and Climate Change

The Great East Japan Earthquake of 2011 was the first time that a single disaster relocated hundreds of districts, and it was completely unprecedented. Professor Suguru Mori is an expert in the field of helping communities rebuild after natural disasters who is interested in taking lessons learned from the Great East Japan Earthquake in the establishment of community relocation that places emphasis on human rights and ethics. As a bachelor student, Mori experienced the Great Hanshin Awaji Earthquake in 1995, gaining the dual perspective of victim and researcher. This highlighted a disconnect. Mori is based in the Division of Architecture, Hokkaido University, Japan, where he is exploring planned community relocation in the context of large-scale disasters and climate change in the Asia-Pacific region, with a particular focus on Koizumi district in Kesennuma city and looking at both past and future risks. In addition to being a researcher, Mori is an architect and planner and a key approach is Action Research, which integrates research and practice to catalyse transformative change. He also uses approaches from the unique academic field of architectural planning research (APR), which was developed in academic circles of the Architectural Institute of Japan (AIJ) and scientifically examines architecture and its design methods.

Analytical and Numerical Investigation of the Behavior of Engineered Cementitious Composite Members under Shear Loads.

This research discusses the performance of engineered cementitious composite (ECC) beams with and without transverse reinforcements using thorough analytical and finite element (FE) approaches under shear. The overall goal of this investigation was to assess the impact of various design characteristics, such as (i) shear span-to-effective depth ratio, (ii) transverse reinforcement ratio, etc., on the shear behavior of ECC beams. Nonlinear three-dimensional (3-D) FE analysis was performed with the commercial software ABAQUS to simulate the shear performance of ECC beams by employing the material properties obtained from the damage plasticity model. The correctness of the proposed FE model was validated with the benchmark experiments available in the literature. The developed FE model accurately computed the ECC beam’s overall load–deflection behavior and failure modes. In addition, the provision available in the Architectural Institute of Japan (AIJ) A-method was successfully employed to assess the shear load-carrying capacity of ECC beams. Furthermore, the effects of transverse reinforcement (pw) and shear span-to-depth ratio (a/d) on the behavior of ECC beams were also investigated. From a detailed parametric study, it was understood that a decreased a/d ratio exhibits enhanced load-carrying capacity for beams with and without stirrups for a particular cross-section. It was also observed that for the entire a/d ratio, the amount of stirrups had no substantial effect on the load-carrying capability of ECC beams.

Effect of Shape on the Temperature of an Opening Jet Plume at the Bottom of a Horizontal Member

In this study, combustion tests, in which the opening condition of a fire source was changed using a large-scale compartment and horizontal member, were conducted. The inner temperature, temperature distribution under the horizontal member, external flame shape, and neutral zone height of the compartment were measured under various opening conditions. The results were analyzed using the temperature prediction equation for the opening jet plume at the bottom of a horizontal member, proposed by the Architectural Institute of Japan (Building fire load and design fire property guideline (draft)), and a review was deemed necessary.

Международные архитектурные форумы в городах Шелкового пути

Освещается работа международных форумов, проводимых Архитектурным институтом Японии с 2009 года и посвященных экспертному обсуждению и концептуальному проектированию исторических городов в системе Шелкового пути. Рассматриваются итоги форума, который впервые был проведен в России – в Самаре и Москве с параллельно развернутым воркшопом для студентов отечественных и зарубежных вузов. Цель форума – сохранение уникального архитектурного наследия; оценка уроков исторической среды; разработка концепций регенерации и эффективного развития стагнирующих исторических территорий городов Шелкового пути на примере Самары.

Shear performance evaluation of PHC piles under different levels of axial load ratio

AbstractPrecast prestressed high‐strength spun concrete (PHC) piles are one of the common types of piles used in Japan due to its high bearing capacity. These piles have been utilized as an industrial standard since the 1970s as part of earthquake‐resilient foundation systems. The focus of this research is to examine the shear performance of PHC piles subjected to large earthquake loads. Three hollow‐section PHC pile specimens were tested under constant compressive or tensile axial load along with quasi‐static antisymmetric lateral load. An investigation using finite element analysis was carried out to reproduce the damage that occurred during the experiment. Comparison between experimental and analytical results were presented in terms of global and local behaviors of the piles. The finite element models were able to simulate axial splitting cracks that occurred for specimens under axial compression load. In addition, a parametric study was conducted to observe the influence of axial load ratio and shear span to diameter ratio on the shear capacity and failure mode of PHC piles. The study results along with the results from a PHC pile database are compared to the shear design equation proposed in the guidelines for PHC piles from the Architectural Institute of Japan (AIJ).

EVALUATION METHOD FOR ALLOWABLE SHORT-TERM FLEXURAL STRENGTH AND YIELD STRENGTH OF CONCRETE-FILLED STEEL TUBULAR BEAM-COLUMNS

According to the Recommendations for Design and Construction of Concrete Filled Steel Tubular Structures from Architectural Institute of Japan, the allowable short-term flexural strength (ASFS) can be used as the yield strength for the restoring force characteristics model of concrete-filled steel tube (CFST) members. Therefore, it is necessary to examine whether the ASFS can be appropriate as an alternative for the yield strength. Furthermore, as the ASFS is typically calculated using the superposition method, the value of the deformation at the superposed strength cannot be evaluated. To address these issues, in this study, numerical analysis was conducted on the moment-curvature relation of CFST column sections using the finite fiber method. The characteristics of the point of ASFS and evaluation method for flexural yield strength in a broad sense were examined using the slope factor and strength satisfaction factor methods. The corresponding slope factor is larger than the value (1/3) that is generally used for the yield strength definition. Therefore, using the ASFS is as the yield strength of the CFST section is reasonable. Additionally, the formula for the curvature at the ASFS was also proposed.

How to estimate fatigue strength of wood material

When wood materials are used for a mechanical structure, the fatigue strength should be estimated due to repeated loads they receive. This paper reveals that the methods to calculate allowable stresses along with American Society for Testing and Materials (ASTM) and Architectural Institute of Japan (AIJ) can take the strength reduction due to fatigue into account because the ASTM/AIJ allowable stresses against the static strength closely resemble the fatigue limit against the wood static strength.

A simplified design approach for predicting the flexural behavior of TRM-strengthened RC beams under cyclic loads

This paper proposes a simplified design approach to predict the flexural behavior of reinforced concrete (RC) beams strengthened by high-performance textile reinforced mortar (TRM) under cyclic loads. Based on the experimental results, the effect of main factors on the beams as well as the effectiveness and reliability of TRM strengthening layer under cyclic loads were examined as per ACI 437 method. The reinforcement ratio of the original RC beams, the textile reinforcement ratio of TRM layer, and the interface bond between the original beam and TRM layer, all have significant influence on the flexural behavior and failure modes of TRM-strengthened beams. The simplified models based on the fib model and the Architectural Institute of Japan (AIJ) standard were suggested to predict the flexural capacity of the strengthened beams. These were also used to evaluate the flexural curve of the beams while employing simplified calculation models of the deflection capacities of the RC beams. The results verified that the simplified capacity curve model presented good accuracy to evaluate the TRM-strengthened RC beams.

Initiatives for Engineer Ethics Education at the Architectural Institute of Japan

Initiatives for Engineer Ethics Education at the Architectural Institute of Japan

RELATIONSHIP BETWEEN DISCOMFORT GLARE AND ELECTROENCEPHALOGRAPHY DURING WORKING IN FRONT OF A WINDOW

It is important to consider discomfort glare in designing comfortable office environment. Architectural Institute of Japan has set UGR and PGSV as design criteria for discomfort glare, but those indicators do not completely reflect the needs for lighting environments due to differences in work behavior. For example, when performing a task that requires concentration, worker may prefer a glare environment to increase one's level of alertness. From the subjective glare and the degree of awakening during work behavior, it is considered necessary to examine the method of indicators that are more suited to actions. Therefore, we focused on the relationship between discomfort glare and EEG, and conducted two experiments with different presentation luminance range. The number of subjects was 10 (5 males and 5 females) in both Experiments 1 and 2, and the age were 21-24 in Experiment 1 and 22-25 in Experiment 2. The experiments were conducted in a space with simulated windows, assuming an office space. The experimental factors were luminance levels of the window and subject' conditions ("Task" is the task of looking at the monitor and doing the calculation work, and "No task" is a task to view the monitor without doing anything). In Exp. 1, luminance levels of the window were 2000, 8000, 14000, 20000 cd/m2, and in Exp. 2, 2000, 5000, 8000, 14000 cd/m2. The measurement indexes were EEG, GSV, and subjective evaluations.

Study on the microstructure and mechanical performance for integrated resistance element welded aluminum alloy/press hardened steel joints

Resistance element welding (REW) is a recently developed hybrid joining process for aluminum (Al)/steel dissimilar materials. In this study, the microstructure and mechanical performance of the Al/press hardened steel (PHS) joints generated using an integrated REW process were investigated. The microstructure of fusion zone (FZ) between rivet and PHS was lath martensite, which was transformed from the fast cooling of austenite. The Al could be divided into four zones according to the microstructure and microhardness distribution: re-solidified zone (RZ), softening zone (SZ), transition zone (TZ) and base metal (BM). The dissolution and coarsening of the precipitates are responsible for the hardness reduction of Al sheet. The variation of mechanical performance was explained in light of the increasing FZ size and the softening Al sheet as heat input rising. Moreover, four block shear models were introduced to predict the peak load of REW joints using the average hardness of SZ in Al sheet, among which the models from Architectural Institute of Japan (AIJ) provided a relatively good prediction. Considering both the average hardness of SZ and sheet thickness, an analytical model was established to predict the variation of critical nugget sizes and explain the failure mode transition.

전산유체해석을 통한 고층 건물의 풍압계수 산정

Recently, Architectural Institute of Japan (AIJ 2015) allowed using CFD analysis for the calculation of wind loads. This means that computer based analysis has reached to similar level with the wind tunnel test due to the improvement of the computing power and CFD analysis theory. This study first dealt with the theoretical background of CFD analysis and conducted the analysis based on the AIJ guideline and the recommendation by the European Cooperation in Science and Technology (COST). Wind tunnel test data provided by Tokyo Polytechnic University were used to verify the reliability of the analysis results. Wind loads with aspect ratios of 3, 4 and 5 were compared to assess the similarity between the analysis results and the wind tunnel test data.

Behavior of square concrete‐filled steel tubular beam‐columns subjected to lateral loads with constant cyclic displacement

AbstractThe objective of this study was to clarify the cyclic behavior of square concrete‐filled steel tube (CFT) beam‐columns subjected to lateral loads with constant cyclic displacement under constant axial load. The test parameters included the effective length‐section depth ratio, axial compression ratio, and rotation angle amplitude. The relationship between the lateral load and the rotation angle are indicated along with the axial strain and load deterioration behavior in this paper. Furthermore, the relationship between the axial strain and load deterioration behaviors is discussed. Moreover, the experimental load is compared with the cross‐section strength, ultimate strength, and allowable strength, as presented in the Architectural Institute of Japan's recommendations for the design and construction of CFT structures; and the relationship between the experimental load and load deterioration behavior is examined.