In this paper, two experiments were conducted to clarify the influence of polymer cement paste mix proportion on in-plane permeability resistance, adhesiveness and watertightness. The followings are concluded from the test results. If the quality of the underlying concrete is poor, fracture at the interface between substrate and hardened paste is likely to occur. If the paste is a softer mix proportion, adhesive failure and moisture migration are more likely to occur due to the formation of a fragile layer, presumably caused by bleeding. These problems can be improved by mixing a standard amount of polymer in this waterproofing system.
Considering the necessity of A simulation tool developed to estimate and qualify waste from building demolition. The tool was developed using BIM enabled 4D-CAD combined with physics and game engines and it simulates the impact and waste output of alternative demolition processes. In addition, Waste Distribution Maps (WDM) are generated to support decision-making. This research represents a significant advancement in applied computing for building demolition waste recycling and improves the information quality available in the definition of building demolition strategies.
The authors have studied Figg’s idea of the drilled hole as an in-situ water absorption testing method. This study aimed to propose an in-situ water absorption testing method for cover concrete up to 50mm from the surface, examining factors affecting the testing results. As a result, the test specifications were determined and the in-situ water absorption assessing method using drilled hole was proposed. The effects of material, mix proportion and curing on the testing results were investigated and the standard deviations of the water absorption data under different water-cement ratios and demolding age were shown.
By yielding under small inter-story deformation, hysteretic dampers installed to a response control structure absorb seismic energy and effectively control the damage to the frame. When designing such a structure, it is important to estimate the maximum deformation and the cumulative plastic deformation of the dampers against ground motions. Especially in the early stage of design, simple methods are useful for the preliminary study of determining the characteristics of the dampers. In this research, the shortcomings of the existing simple methods are discussed and a new method is proposed. Its accuracy and applicability are investigated using numerical examples.
The seismic response records of acceleration and strain of a three-story steel structure building were obtained and analyzed. From the strain measurement, the shear force actually applied to the column or the story could be obtained, and the frame stiffness could be calculated by combining this with the acceleration response measurement result. It was shown that the change in frame stiffness could be separated from the change in predominant frequency, and that the change in the frame stiffness was not as great as the change in the predominant frequency.
In design of steel-framed base isolated buildings, it is necessary to consider the stiffness and placement of the braces to prevent uplift of rubber bearings. This paper proposes a prediction method for uplift of rubber bearings of low to mid-rise braced, base isolated buildings subject to horizontal seismic ground motion. By using an equivalent spring model that considers the effect of vertical deformation of rubber bearings, a prediction equation for the axial compressive stress was derived as a function of inter-story deformation. The equation enables prediction of uplift of rubber bearings for different brace stiffnesses without the need for analysis.
In response estimation of seismic control structures, it is necessary to consider the performance degradation of dampers due to long-period seismic motion. In this paper the focus is given to structures with shear strain dependent nonlinear viscoelastic dampers. A method is proposed to predict the damper dissipated energy considering performance degradation in earthquakes. The dissipated energy is used to predict the maximum deformation response of the structure using existing energy methods. New expression are proposed for the evaluation of the equivalent number of cycles and the effective damper deformation ratio. The accuracy of these prediction methods is then evaluated.
To clarify the influence of the head tie-beams on the restoring force of the traditional wooden frame structure, static loading tests were conducted on the model specimens with four different kinds of head tie-beam specifications subjected to the two different stages of dead loads. It was clarified that the existence of the head tie-beam greatly contributed to the performance of the specimens regardless of the specifications of the head tie-beams. Ancient specification head tie-beam showed an eccentric moment-resisting performance depending on the opening angle between column and beam. Other head tie-beams, however, had no opening angle dependency.
Short-term allowable shear force of RC multi-story walls for safety assurance and damage control was specified in AIJ standard. However, this allowable force for multi-story shear walls with door openings was defined by limited data. In this study, based on the experimental results of five 1/4 scale multi-story shear wall specimens with various disposition of vertically aligned door openings, several strength reduction factors related to door openings were verified for the short-term allowable force based on the observed strengths for safety assurance and the observed residual crack widths for damage control. Consequently, an optimal reduction factor was suggested.
In this study, static loading tests were performed to investigate the structural performance of RC frames with CLT walls. The experimental investigation revealed that the presence of CLT infill significantly increased the initial stiffness and strength of RC frame regardless the RC frame-CLT infill connections. The post-peak strength of the RC frame with CLT infill did not drop below 80% of the maximum strength even in a large drift of 10%. These results clarified that the presence of CLT infill within RC frame has a beneficial effect on the seismic performance of RC frame structure.
Recently, artificial intelligence has been used in various fields, however researches of predicting load-displacement relationships for structural members are shortage. In this study, the shear force – shear displacement (Q -𝛿𝑆) relationships of post-installed anchors were predicted using machine learning with Decision Tree and Neural Network. As a result, the prediction results by Neural Network were the most accurate of the applied four methods. In addition, the prediction results of the Neural Network were compared with the evaluation results of the FEM analysis and Dowel model, which are the conventional methods. Finally, Neural Network was the most accurate algorism.
In this paper, out-of-plane bending stiffness of column-end connection between square hollow section column and thick panel with different width was investigated by loading test and finite element analysis. From the results, column-end connection of corner-type under 45-degree directional force has the smallest stiffness, and of which section dose not remain plane, and proportion of bending resistance caused by partial deformation of column in column-end bending resistance is very small. Therefore, method to estimate out-of-plane bending stiffness of column-end was proposed based on deformation of diaphragm of hollow section of panel and directly above panel.
Finite element analysis is conducted on the built-up beam using hot-rolled channel steel subjected to vertical load and cyclic antisymmetric moment. The following were obtained.
1.The separation between channel steels will affect the strength and deformation of the built-up beam.
2.Suitable bolt arrangements can prevent capacity deterioration, H≦S0≦1.5H and S≦3H are recommended.
3.The equal arrangement of lateral bracing is proposed. For maximum amplitude is 6θp, the spacing is 10 times beam-width for λy≦250, and additional bracings are required for λy＞250.
The long columns in atrium often buckle by the non-sway mode due to the surrounding bracing frame. The objective of this study is to propose an evaluation method for the effective length factor of the long column. Evaluation formula is obtained by using the energy method, and the effective length factors are calculated taking story height ratio, flexural stiffness ratio and axial load ratio as the parameters. The accuracy is verified comparing with the exact effective length obtained using the buckling slope deflection method, and it is shown that the proposed formula is useful for the actual conditions.
Design equations for the elastic critical local buckling are considered simplified conditions, such as uniformly compression with simply supported edges or idealized boundary conditions; however, I–beams are also subjected to uniformly distributed loads such as seismic and live loads in reality. This study aims to clarify the effect under bending moments and uniformly distributed loads, on the local buckling strength of web plate of I–beams. It was concluded that uniformly distributed load tends to cause shear–type local buckling. Moreover, a discriminant equation for local buckling mode and a design equation considering the combined loads was presented.
The inelastic static analysis pushover models of the wall-type precast reinforced concrete (WPC) residential buildings are proposed. The models are composed of beam elements for walls and inelastic springs for the connections. The inelastic force-restoration relationships of the shear walls and connections are defined based on review of past research. The defined relationships are verified with experiments of shear wall frames in the transverse direction of WPC buildings. The proposed models well simulate the lateral strength and sequence of damages such as shear cracks and flexural yielding of the shear wall panels, and shear slips of horizontal connections.
Frame of passively-controlled building is typically composed of steel beam, column, gusset plate and concrete slab. Its behavior is determined by the interaction of the nonlinear behavior of each component. Authors have proposed a new test method to research the behavior of frame of passively-controlled building, and carried out tests for bare girder using it. In this paper, we will carry out tests applying the test method to the subassembly with concrete slab. We investigate the behavior of the beam, column, and gusset-plate to clarify how the concrete slab affects the frame behavior in the passively-controlled building.