Structural safety reliability of concrete buildings of HTR-PM in accidental double-ended break of hot gas ducts

Guo, Quanquan,Wang, Shaoxu,Chen, Shenggang,Sun, Yunlong Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.5

Safety analysis of nuclear power plant (NPP) especially in accident conditions is a basic and necessary issue for applications and commercialization of reactors. Many previous researches and development works have been conducted. However, most achievements focused on the safety reliability of primary pressure system vessels. Few literatures studied the structural safety of huge concrete structures surrounding primary pressure system, especially for the fourth generation NPP which allows existing of through cracks. In this paper, structural safety reliability of concrete structures of HTR-PM in accidental double-ended break of hot gas ducts was studied by Exceedance Probability Method. It was calculated by Monte Carlo approaches applying numerical simulations by Abaqus. Damage parameters were proposed and used to define the property of concrete, which can perfectly describe the crack state of concrete structures. Calculation results indicated that functional failure determined by deterministic safety analysis was decided by the crack resistance capability of containment buildings, whereas the bearing capacity of concrete structures possess a high safety margin. The failure probability of concrete structures during an accident of double-ended break of hot gas ducts will be 31.18%. Adding the consideration the contingency occurrence probability of the accident, probability of functional failure is sufficiently low.

Impact response of steel-concrete composite panels: Experiments and FE analyses

Weiyi Zhao,Quanquan Guo,Xuqiang Dou,Yao Zhou,Yinghua Ye 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.26 No.3

A steel-concrete composite (SC) panel typically consists of two steel faceplates and a plain concrete core. This paper investigated the impact response of SC panels through drop hammer tests and numerical simulations. The influence of the drop height, faceplate thickness, and axial compressive preload was studied. Experimental results showed that the deformation of SC panels under impact consists of local indentation and overall bending. The resistance of the panel significantly decreased after the local failure occurred. A three-dimensional finite element model was established to simulate the response of SC panels under low-velocity impact, in which the axial preload could be considered reasonably. The predicted displacements and impact force were in good agreement with the experimental results. Based on the validated model, a parametric study was conducted to further discuss the effect of the axial compressive preload.

Experimental Research on Vertical Mechanical Performance of Embedded Through-penetrating Steel-Concrete Composite Joint in High-Temperature Gas-Cooled Reactor Pebble-Bed Module

Peiyao Zhang,Quanquan Guo,Sen Pang,Yunlun Sun,Yan Chen 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.1

The high-temperature gas-cooled reactor pebble-bed module project is the first commercial Generation-IV NPP(Nuclear Power Plant) in China. A new joint is used for the vertical support of RPV(ReactorPressure Vessel). The steel corbel is integrally embedded into the reactor-cabin wall through eightasymmetrically arranged pre-stressed high-strength bolts, achieving the different path transmission ofshear force and moment. The vertical monotonic loading test of two specimens is conducted. The resultsshow that the failure mode of the joint is bolt fracture. There is no prominent yield stage in the wholeloading process. The stress of bolts is linearly distributed along the height of corbel at initial loading. Asthe load increases, the height of neutral axis of bolts gradually decreases. The upper and lower edges ofthe wall opening contact the corbel plate to restrict the rotation of the corbel. During the loading, thepre-stress of some bolts decreases. The increase of the pre-stress strength ratio of bolts has no noticeableeffect on the structure stiffness, but it reduces the ultimate bearing capacity of the joint. A simplifiedcalculation model for the elastic stage of the joint is established, and the estimation results are in goodagreement with the experimental results

Nonlinear model to predict the torsional response of U-shaped thin-walled RC members

Shenggang Chen,Yinghua Ye,Quanquan Guo,Shaohong Cheng,Bo Diao 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.60 No.6

Based on Vlasov‟s torsional theory of open thin-walled members and the nonlinear constitutive relations of materials, a nonlinear analysis model to predict response of open thin-walled RC members subjected to pure torsion is proposed in the current study. The variation of the circulatory torsional stiffness and warping torsional stiffness over the entire loading process and the impact of warping shear deformation on the torsion-induced rotation of the member are considered in the formulation. The torque equilibrium differential equation is then solved by Runge-Kutta method. The proposed nonlinear model is then applied to predict the behavior of five U-shaped thin-walled RC members under pure torsion. Four of them were tested in an earlier experimental study by the authors and the testing data of the fifth one were reported in an existing literature. Results show that the analytical predictions based on the proposed model agree well with the experimental data of all five specimens. This clearly shows the validity of the proposed nonlinear model analyzing behavior of U-shaped thin-walled RC members under pure torsion.

Experimental and Analytical Studies of U-Shaped Thin-Walled RC Beams Under Combined Actions of Torsion, Flexure and Shear

Jianchao Xu,Shenggang Chen,Quanquan Guo,Yinghua Ye,Bo Diao,Y. L. Mo 한국콘크리트학회 2018 International Journal of Concrete Structures and M Vol.12 No.3

U-shaped thin-walled concrete bridge beams usually suffer the combined actions of flexure, shear and torsion, but no research about the behavior of U-shaped thin-walled RC beams under combined actions has been reported in literature. Three large specimens of U-shaped thin-walled RC beams were tested under different torque–bending moment ratios (T–M ratios) of 1:5, 1:1 and 1:0 to investigate the mechanical responses such as crack patterns, reinforcement strains, failure modes and ductility. The testing results showed that ductile flexural failures occurred for all three of the U-shaped thin-walled beam specimens, although the combined shear effect of circulatory torque, warping torque and shear force increased as the T–M ratio increased from 1:5 via 1:1 to 1:0, reflected by diagonal cracks and stirrup strains. More specifically, basically symmetrical flexural failure was dominated by the bending moment when the T–M ratio was 1:5; flexural failure of the loaded half of the U-shaped thin-walled section was dominated by the combined action of the bending moment and warping moment, while there were only a few cracks on the other half of the U-shaped section when the T–M ratio was 1:1; and anti-symmetrical flexural failure was dominated by the warping moment when the T–M ratio was 1:0 (pure torsion). A simple method to calculate the ultimate load of such U-shaped thin-walled RC beams under different T–M ratios was suggested, and the calculating results were corresponding well with the experimental results.

Strain rate effect of steel-concrete composite panel indented by a hemispherical rigid body

Weiyi Zhao,Lin Wang,Guotao Yang,Ziguo Wang,Zepeng Gao,Quanquan Guo 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.36 No.6

This paper presents numerical and theoretical investigations on the strain rate in steel-concrete composite (SC) panels under low-velocity impact of a hemispherical rigid body. Finite element analyses were performed on five specimens with different loading rates. The impact energy was kept constant to eliminate its influence by simultaneously altering the velocity and mass of the projectile. Results show that the strain rate in most parts of the specimens was low and its influence on bearing capacity and energy dissipation was limited in an average sense of space and time. Therefore, the strain rate effect can be ignored for the analyses of global deformation. However, the strain rate effect should be considered in local contact problems. Equations of the local strain and strain rate were theoretically derived.