Seismic response characteristics of base-isolated AP1000 nuclear shield building subjected to beyonddesign basis earthquake shaking

Dayang Wang,Chuli Zhuang,Yongshan Zhang 한국원자력학회 2018 Nuclear Engineering and Technology Vol.50 No.1

Because of the design and construction requirements, the nuclear structures need to maintain thestructural integrity under both design state and extreme earthquake shaking. The base-isolation technologycan significantly reduce the damages of structures under extreme earthquake events, andeffectively protect the safeties of structures and internal equipment. This study proposes a base-isolationdesign for the AP1000 nuclear shield building on considering the performance requirements of theseismic isolation systems and devices of shield building. The seismic responses of isolated and nonisolatedshield buildings subjected to design basis earthquake (DBE) shaking and beyond-design basisearthquake (BDBE) shaking are analyzed, and three different strategies for controlling the displacementssubjected to BDBE shaking are performed. By comparing with nonisolated shield buildings, the flooracceleration spectra of isolated shield buildings, relative displacement, and base shear force are significantlyreduced in high-frequency region. The results demonstrate that the base-isolation technology isan effective approach to maintain the structural integrity which subjected to both DBE and BDBE shaking. A displacement control design for isolation layers subjected to BDBE shaking, which adopts fluiddampers for controlling the horizontal displacement of isolation layer is developed. The effectiveness ofthis simple method is verified through numerical analysis

Research on the impact effect of AP1000 shield building subjected to large commercial aircraft

Wang, Xiuqing,Wang, Dayang,Zhang, Yongshan,Wu, Chenqing Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.5

This study addresses the numerical simulation of the shield building of an AP1000 nuclear power plant (NPP) subjected to a large commercial aircraft impact. First, a simplified finite element model (F.E. model) of the large commercial Boeing 737 MAX 8 aircraft is established. The F.E. model of the AP1000 shield building is constructed, which is a reasonably simplified reinforced concrete structure. The effectiveness of both F.E. models is verified by the classical Riera method and the impact test of a 1/7.5 scaled GE-J79 engine model. Then, based on the verified F.E. models, the entire impact process of the aircraft on the shield building is simulated by the missile-target interaction method (coupled method) and by the ANSYS/LS-DYNA software, which is at different initial impact velocities and impact heights. Finally, the laws and characteristics of the aircraft impact force, residual velocity, kinetic energy, concrete damage, axial reinforcement stress, and perforated size are analyzed in detail. The results show that all of them increase with the addition to the initial impact velocity. The first four are not very sensitive to the impact height. The engine impact mainly contributes to the peak impact force, and the peak impact force is six times higher than that in the first stage. With increasing initial impact velocity, the maximum aircraft impact force rises linearly. The range of the tension and pressure of the reinforcement axial stress changes with the impact height. The perforated size increases with increasing impact height. The radial perforation area is almost insensitive to the initial impact velocity and impact height. The research of this study can provide help for engineers in designing AP1000 shield buildings.

A combination method to generate fluctuating boundary conditions for large eddy simulation

Dayang Wang,Y. Zhou,X.J. Yu,K.T. Tse 한국풍공학회 2015 Wind and Structures, An International Journal (WAS Vol.20 No.4

A Combination Random Flow Generation (CRFG) technique for obtaining the fluctuatinginflow boundary conditions for Large Eddy Simulation (LES) is proposed. The CRFG technique wasdeveloped by combining the typical RFG technique with a novel calculation of k and  to estimate thelength- and time-scales (l, τ) of the target fluctuating turbulence field used as the inflow boundary conditions. Through comparatively analyzing the CRFG technique and other existing numerical/experimental results,the CRFG technique was verified for the generation of turbulent wind velocity fields with prescribedturbulent statistics. Using the turbulent velocity fluctuations generated by the CRFG technique, a series ofLESs were conducted to investigate the wind flow around S-, R-, L- and U-shaped building models. As thepressures of the models were also measured in wind tunnel tests, the validity of the LES, and theeffectiveness of the inflow boundary generated by the CRFG techniques were evaluated through comparingthe simulation results to the wind tunnel measurements. The comparison showed that the LES accuratelyand reliably simulates the wind-induced pressure distributions on the building surfaces, which indirectlyvalidates the CRFG technique in generating realistic fluctuating wind velocities for use in the LES. Inaddition to the pressure distribution, the LES results were investigated in terms of wind velocity profilesaround the building models to reveal the wind flow dynamics around bluff bodies. The LES resultsquantitatively showed the decay of the bluff body influence when the flow moves away from the buildingmodel.

Wind resistance performance of a continuous welding stainless steel roof under static ultimate wind loading with testing and simulation methods

DaYang Wang,Zhendong Zhao,Tong Ou,Zhiyong Xin,Mingming Wang,Yongshan Zhang 한국풍공학회 2021 Wind and Structures, An International Journal (WAS Vol.32 No.1

Ultrapure ferritic stainless steel provides a new generation of long-span metal roof systems with continuous welding technology, which exhibits many unknown behaviors during wind excitation. This study focuses on the wind-resistant capacity of a new continuous welding stainless steel roof (CWSSR) system. Full-scale testing on the welding joints and the CWSSR system is performed under uniaxial tension and static ultimate wind uplift loadings, respectively. A finite element model is developed with mesh refinement optimization and is further validated with the testing results, which provides a reliable way of investigating the parameter effect on the wind-induced structural responses, namely, the width and thickness of the roof sheeting and welding height. Research results show that the CWSSR system has predominant wind-resistant performance and can bear an ultimate wind uplift loading of 10.4 kPa without observable failures. The welding joints achieve equivalent mechanical behaviors as those of base material is produced with the current of 65 A. Independent structural responses can be found for the roof sheeting of the CWSSR system, and the maximum displacement appears at the middle of the roof sheeting, while the maximum stress appears at the connection supports between the roof sheeting with a significant stress concentration effect. The responses of the CWSSR system are greatly influenced by the width and thickness of the roof sheeting but are less influenced by the welding height. Ultrapure ferritic stainless steel provides a new generation of long-span metal roof systems with continuous welding technology, which exhibits many unknown behaviors during wind excitation. This study focuses on the wind-resistant capacity of a new continuous welding stainless steel roof (CWSSR) system. Full-scale testing on the welding joints and the CWSSR system is performed under uniaxial tension and static ultimate wind uplift loadings, respectively. A finite element model is developed with mesh refinement optimization and is further validated with the testing results, which provides a reliable way of investigating the parameter effect on the wind-induced structural responses, namely, the width and thickness of the roof sheeting and welding height. Research results show that the CWSSR system has predominant wind-resistant performance and can bear an ultimate wind uplift loading of 10.4 kPa without observable failures. The welding joints achieve equivalent mechanical behaviors as those of base material is produced with the current of 65 A. Independent structural responses can be found for the roof sheeting of the CWSSR system, and the maximum displacement appears at the middle of the roof sheeting, while the maximum stress appears at the connection supports between the roof sheeting with a significant stress concentration effect. The responses of the CWSSR system are greatly influenced by the width and thickness of the roof sheeting but are less influenced by the welding height

Damage and deformation of new precast concrete shear wall with plastic damage relocation

DaYang Wang,Qihao Han,Shenchun Xu,Zhigang Zheng,Quantian Luo,Jihua Mao 국제구조공학회 2023 Steel and Composite Structures, An International J Vol.48 No.4

To avoid premature damage to the connection joints of a conventional precast concrete shear wall, a new precast concrete shear wall system (NPSW) based on a plastic damage relocation design concept was proposed. Five specimens, including one monolithic cast-in-place concrete shear wall (MSW) as a reference and four NPSWs with different connection details (TNPSW, INPSW, HNPSW, and TNPSW-N), were designed and tested by lateral low-cyclic loading. To accurately assess the damage relocation effect and quantify the damage and deformation, digital image correlation (DIC) and conventional data acquisition methods were used in the experimental program. The concrete cracking development, crack area ratio, maximum residual crack width, curvature of the wall panel, lateral displacement, and deformed shapes of the specimens were investigated. The results showed that the plastic damage relocation design concept was effective; the initial cracking occurred at the bottom of the precast shear wall panel (middle section) of the proposed NPSWs. The test results indicated that the crack area ratio and the maximum residual crack width of the NPSWs were less than those of the MSW. The NPSWs were deformed continuously; significant distortions did not occur in their connection regions, demonstrating the merits of the proposed NPSWs. The curvatures of the middle sections of the NPSWs were lower than that of the MSW after a drift ratio of 0.5%. Among the NPSWs, HNPSW demonstrated the best performance, as its crack area ratio, concrete damage, and maximum residual crack width were the lowest.

Mechanical Behavior of Nine Tree-Pool Joints Between Large Trees and Buildings

Wang Dayang,Liu Mingqi,Ou Tong,Zhang Yongshan 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.8

Nine types of tree-pool joints designed to plant large trees on building structures were proposed in this study. Solid finite elementmodel considering plastic damage constitutive relationship for the tree-pool joints were built using ABAQUS software platform. Based on comparative analysis of six different mesh generation methods of the 3D tree-pool joint model, an optimized meshgeneration method was determined and verified considering both the calculation time and accuracy. The mechanical behavior of thenine tree-pool joints, such as peak tension/compression stress, hysteretic energy dissipation performance, plastic damageperformance and corresponding crack development process, were studied in detail under horizontal and vertical loads. The resultsshow that the tree-pool joints with steel strengthened form and composite strengthened form have superior horizontal and verticalbearing capacity. Similarly, they also have stable hysteretic energy dissipation performance, minimal plastic damage and crackdevelopment relatively in vertical ultimate load. However, the tree-pool joints with other strengthened forms, such as forms of innerbeamand inner-beam combined with ring bracket, show poor mechanical properties. Although there is a certain degree ofperformance improvement for these tree-pool joints relative to non-strengthened joints, narrow hysteretic curves, apparent strength/stiffness degradation characteristics, extensive material damage and crack development can be found. Results of this paper do shinesome lights on how to design reasonable and reliable tree-pool joints in building structures.

A combination method to generate fluctuating boundary conditions for large eddy simulation

Wang, Dayang,Yu, X.J.,Zhou, Y.,Tse, K.T. Techno-Press 2015 Wind and Structures, An International Journal (WAS Vol.20 No.4

A Combination Random Flow Generation (CRFG) technique for obtaining the fluctuating inflow boundary conditions for Large Eddy Simulation (LES) is proposed. The CRFG technique was developed by combining the typical RFG technique with a novel calculation of k and ${\varepsilon}$ to estimate the length- and time-scales (l, ${\tau}$) of the target fluctuating turbulence field used as the inflow boundary conditions. Through comparatively analyzing the CRFG technique and other existing numerical/experimental results, the CRFG technique was verified for the generation of turbulent wind velocity fields with prescribed turbulent statistics. Using the turbulent velocity fluctuations generated by the CRFG technique, a series of LESs were conducted to investigate the wind flow around S-, R-, L- and U-shaped building models. As the pressures of the models were also measured in wind tunnel tests, the validity of the LES, and the effectiveness of the inflow boundary generated by the CRFG techniques were evaluated through comparing the simulation results to the wind tunnel measurements. The comparison showed that the LES accurately and reliably simulates the wind-induced pressure distributions on the building surfaces, which indirectly validates the CRFG technique in generating realistic fluctuating wind velocities for use in the LES. In addition to the pressure distribution, the LES results were investigated in terms of wind velocity profiles around the building models to reveal the wind flow dynamics around bluff bodies. The LES results quantitatively showed the decay of the bluff body influence when the flow moves away from the building model.

Experimental Study on Mechanical Properties of Continuous Welding Stainless Steel Roof System under Temperature Effect

Mingming Wang,Tong Ou,Zhiyong Xin,Dayang Wang,Yongshan Zhang 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.2

Stainless steel is used as a new generation of long-span metal roof systems with continuous welding technology, which exhibits many unknown behaviors during temperature action. This study focuses on the temperature effect of a continuous welded stainless steel roof (CWSSR) system and analyzes the stress distribution of plate rib (PR), plate surface (PS), and support (SU), and the horizontal and vertical displacement. Furthermore, the thermal action of the CWSSR system is comprehensively analyzed considering different loading rates, constant temperature time, and the cycle number. Research results show that the stress concentration and thermal expansion of the CWSSR system are obvious, and fatigue damage occurs under long-term temperature action. The responses of the CWSSR system are greatly influenced by the loading rate and the cycle number but are less influenced by the constant temperature time. Loading rate and the cycle number mainly affect the plate surface stress and vertical displacement. The plate surface stress and vertical displacement peak increased by 34.6% and 29.6% with the loading rate, and changed by 32.4% and 42.5% with the cycle number. Cyclic loading reduces support tensile capacity by 4.4%. The research results can provide reference for the design and application of temperature field resistance of the CWSSR system.

Optimum study on wind-induced vibration control of high-rise buildings with viscous dampers

Zhou, Yun,Wang, DaYang,Deng, XueSong Techno-Press 2008 Wind and Structures, An International Journal (WAS Vol.11 No.6

In this paper, optimum methods of wind-induced vibration control of high-rise buildings are mainly studied. Two optimum methods, genetic algorithms (GA) method and Rayleigh damping method, are firstly employed and proposed to perform optimum study on wind-induced vibration control, six target functions are presented in GA method based on spectrum analysis. Structural optimum analysis programs are developed based on Matlab software to calculate wind-induced structural responses. A high-rise steel building with 20-storey is adopted and 22 kinds of control plans are employed to perform comparison analysis to validate the feasibility and validity of the optimum methods considered. The results show that the distributions of damping coefficients along structural height for mass proportional damping (MPD) systems and stiffness proportional damping (SPD) systems are entirely opposite. Damping systems of MPD and GAMPD (genetic algorithms and mass proportional damping) have the best performance of reducing structural wind-induced vibration response and are superior to other damping systems. Standard deviations of structural responses are influenced greatly by different target functions and the influence is increasing slightly when higher modes are considered, as shown fully in section 5. Therefore, the influence of higher modes should be considered when strict requirement of wind-induced vibration comfort is needed for some special structures.

Parametric Study on Cyclic Behavior of Modular Assembly Composite Walls with Connection to Boundary Beam

Tong Ou,Dayang Wang,Yongshan Zhang,Hao Li 한국강구조학회 2021 International Journal of Steel Structures Vol.21 No.5

This study focuses on the investigation of seismic performance of modular assembly composite shear wall (MACW) system, which is connected to boundary beams only. The fi nite element method is employed to establish the numerical model of the MACW system and experimental data is adopted to validate the simulation. To clearly show the seismic performance of the system, seven design parameters with 36 computational cases, including height-to-span and height-to-thickness ratios of steel plate, bolt spacing, spacing between the concrete plate and connection steel plate, thicknesses of the connection steel plate and concrete plate, and the number of composite wall modules, are discussed on mechanical property and energy dissipation capacity in details. The results show that ratios of height-to-span and height-to-thickness have a signifi cant infl uence on mechanical bearing and energy dissipation properties in comparison to the other fi ve parameters. Combining systematic seismic behaviors, such as hysteresis property, out-of-plane displacement, and equivalent damping ratio, the optimal values of the above seven parameters are recommended to be 2, 600, 100, 30, 8, 50, and 2 mm respectively. Stiff ness ratios between the post-yield and initial stiff ness of all the 36 models are mainly in the range of (2.6%, 5.5%).