Size-dependency of concrete-filled steel tubes subject to impact loading

A floating two-stage buffer collision-prevention system (FTBCPS) has been proposed to reduce the impact loads on the bridge pier in this paper. The anti-collision process can be mainly divided into two stages. First, reduce the ship velocity and change the ship initial moving direction with the stretching and fracture of the polyester ropes. Second, consume the ship kinetic energy with the huge damage and deformation of the FTBCPS and the ship. The main feature of the FTBCPS lies in the first stage and most of the ship kinetic energy can be dissipated before the ship directly impacts on the bridge pier. The contact stiffness value between the ship and the FTBCPS can be a significant factor in the first stage and the calculation method of it is the focus of this paper. The contact force, the internal force and the general equation of motion have been given in the first part. The structure model of the ship and the FTBCPS are then established in the ANSYS Workbench. After that, 38 typical load cases of the ship impacting on the FTBCPS are conducted in LS-DYNA. The reduction processes of the ship kinetic energy and the ship velocity in different load cases have been investigated. It can be summarized that the impact angle and the ship initial velocity are the main factors in the energy and velocity dissipation process. Moreover, the local impact force-depth curves have also been studied and the impact angle is found to be the only significant factor on the ship impact process. Next, the impact force-depth curves with different impact angles are fitted and the contact stiffness values are accordingly calculated. Finally, the impact depth range, the validity of the local simulation results and the consistency of the fitted stiffness value are verified respectively, demonstrating that the fitted stiffness values are applicable in the global analysis.

Section: Finite Element Modelmentioning

confidence: 99%

Initial response mechanism and local contact stiffness analysis of the floating two-stage buffer collision-prevention system under ship colliding

Lü

Chen

Gao

et al. 2021

“…Loland damage model (Loland, 1980), Mazars damage model (Mazars, 1984), Sidoroff damage model (Supartono and Sidoroff, 1985), and Krajcinovic damage model (Krajcinovic, 1983) are most widely used. Meanwhile, a growing number of research work has been conducted aiming to assess the damages caused to steel structures, concrete-filled steel tubes, and other types of structures subject to dynamic or impact loading (Heidarpour and Bradford, 2011;Mirmomeni et al, 2015Mirmomeni et al, , 2017. These indicate that more and more attention has been paid to the study of structural responses under dynamic loading.…”

Section: Introductionmentioning

confidence: 99%

Mechanical properties of cracked concrete under uniaxial tensile load

2020

Cracks have a serious impact on the safety of concrete structures, and the tensile behavior of concrete is the key to control generation and propagation of crack. To improve the safety of concrete structures, it is crucial to understand the mechanical properties of cracked concrete under uniaxial tensile load. In this article, dynamic tensile test and tensile test after different fatigue damage were conducted to investigate the mechanical properties of cracked concrete. First, the damage evolution law of cracked concrete under dynamic tensile load was investigated by means of [Formula: see text] ([Formula: see text]: crack mouth opening displacement) control mode whereupon the relationship of stress– dCMOD considering rates effect was obtained. Then, the change law of cracked concrete under uniaxial tensile load after fatigue damage was studied by analyzing four mechanical parameters including tensile strength, elastic modulus, critical displacement, and fracture toughness. The empirical formulas of the four parameters with numbers of fatigue cycles are given. Furthermore, acoustic emission technology was applied additionally.

“…The effects of high temperature, impact speed, steel ratio, and slenderness ratio on the high temperature impact properties of CFST columns were studied. Mirmomeni et al (2017) studied the influence of size effect on the mechanical properties of CFST columns under axial impact loads. The results show that the slenderness ratio and width–thickness ratio of CFST columns have influence on its dynamic compression performance, stress–strain distribution, and failure mode.…”

Section: Introductionmentioning

confidence: 99%

Stress monitoring and impact bearing capacity of circular concrete-filled steel tubular short columns under axial impact loads

Gao

et al. 2019

Compared with the traditional reinforced concrete columns, the concrete-filled steel tubular columns with a better restraint effect of steel tube on core concrete showed higher bearing capacity and ductility under static loads. However, except static loads, concrete-filled steel tubular columns are commonly exposed to the extreme dynamic loads including earthquake, explosion, and impact. The study on dynamic behavior of concrete-filled steel tubular columns is extremely significant to ensure their safety against such dynamic loads. In this article, a polyvinylidene fluoride piezoelectric smart sensor was proposed to monitor the axial impact bearing capacity of specimen based on stress monitoring under impact loads. The concrete-filled steel tubular columns with smart sensor embedded were tested, which considered the effects of both hammer impact heights and steel tube thickness on the axial impact bearing capacity. The impact bearing capacity calculated based on the monitoring results of polyvinylidene fluoride sensor is in good agreement with the measured values, which verifies the feasibility of this method. Moreover, it is found that the failure mode of concrete-filled steel tubular short columns is the local tearing failure or local buckling. In addition, non-linear finite element models were also established to study the effect of different parameters on the axial bearing capacity. The simplified formula for calculating the axial impact bearing capacity of concrete-filled steel tubular short columns was proposed based on the large amount verified model. Through the comparison between the calculation value and the test value, the formula is found to well reflect the axial impact bearing capacity of concrete-filled steel tubular short columns, which provides a reference for similar research.