Multi-dimensional seismic response control of offshore platform structures with viscoelastic dampers (II-Experimental study)

He, Xiao-Yu,Zhao, Tie-Wei,Li, Hong-Nan,Zhang, Jun Techno-Press 2016 Structural monitoring and maintenance Vol.3 No.2

Based on the change of traditional viscoelastic damper structure, a brand-new damper is designed to control simultaneously the translational vibration and the rotational vibration for platforms. Experimental study has been carried out on the mechanical properties of viscoelastic material and on its multi-dimensional seismic response control effect of viscoelastic damper. Three types of viscoelastic dampers with different shapes of viscoelastic material are designed to test the influence of excited frequency, strain amplitude and ambient temperature on the mechanical property parameters such as circular dissipation per unit, equivalent stiffness, loss factor and storage shear modulus. Then, shaking table tests are done on a group of single-storey platform systems containing one symmetric platform and three asymmetric platforms with different eccentric forms. Experimental results show that the simulation precision of the restoring force model is rather good for the shear deformation of viscoelastic damper and is also satisfied for the torsion deformation and combined deformations of viscoelastic damper. The shaking table tests have verified that the new-type viscoelastic damper is capable of mitigating the multi-dimensional seismic response of offshore platform.

Superhydrophobic-Superoleophilic SiO2/Polystyrene Porous Micro/nanofibers for Efficient Oil-Water Separation

Yadan Ding,Dan Xu,Hong Shao,Tie Cong,Xia Hong,Huiying Zhao 한국섬유공학회 2019 Fibers and polymers Vol.20 No.10

SiO2/polystyrene porous micro/nanofibers with superhydrophobic and superoleophilic properties were preparedby facile electrospinning method. The spindle-beads-on-string structured fibers were found to be more hydrophobic thanthose without the beads. The doping of nano-SiO2 endowed the fibers with porous structure, and thus further increased thewater contact angle from 139 o to 153 o. Simultaneously, the oil contact angle of 0 o was obtained. The superhydrophobicsuperoleophilicmicro/nanofibers could selectively absorb oil from water within eight seconds. The oil sorption processfollowed pseudo-first order kinetic model. The absorption mechanism was proved to be physical encapsulation by Fouriertransform infrared technique. The maximum sorption capacity for highly viscous silicone oil was up to 122.7 g/g. It is higherthan many recently reported values. The porous micro/nanofibers exhibit significant value in oil-water separation.

Experimental study on Chinese ancient timber-frame building by shaking table test

Zhang, Xi-Cheng,Xue, Jian-Yang,Zhao, Hong-Tie,Sui, Yan Techno-Press 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.40 No.4

A one-story, wooden-frame, intermediate-bay model with Dou-Gon designed according to the Building Standards of the Song Dynasty (A.D.960-1279), was tested on a unidirectional shaking table. The main objectives of this experimental study were to investigate the seismic performance of Chinese historic wooden structure under various base input intensities. El Centro wave (N-S), Taft wave and Lanzhou wave were selected as input excitations. 27 seismic geophones were instrumented to measure the real-time displacement, velocity and acceleration respectively. Dynamic characteristics, failure mode and hysteretic energy dissipation performance of the model are analyzed. Test results indicate that the nature period and damping ratio of the model increase with the increasing magnitude of earthquake excitation. The nature period of the model is within 0.5~0.6 s, the damping ratio is 3~4%. The maximum acceleration dynamic magnification factor is less than 1 and decreases as the input seismic power increases. The frictional slippage of Dou-Gon layers (corbel brackets) between beams and plates dissipates a certain amount of seismic energy, and so does the slippage between posts and plinths. The mortise-tenon joint of the timber frame dissipates most of the seismic energy. Therefore, it plays a significant part in shock absorption and isolation.

Experimental study on mechanical performances of lattice steel reinforced concrete inner frame with irregular section columns

Jian-yang Xue,Liang Gao,Zuqiang Liu,Hong-tie Zhao,Zongping Chen 국제구조공학회 2014 Steel and Composite Structures, An International J Vol.16 No.3

Based on the test on a 1/2.5-scaled model of a two-bay and three-story inner frame composed of reinforced concrete beams and lattice steel reinforced concrete (SRC) irregular section columns under low cyclic reversed loading, the failure process and the features of the frame were observed. The subsequence of plastic hinges of the structure, the load-displacement hysteresis loops and the skeleton curve, load bearing capacity, inter-story drift ratio, ductility, energy dissipation and stiffness degradation were analyzed. The results show that the lattice SRC inner frame is a typical strong column-weak beam structure. The hysteresis loops are spindle-shaped, and the stiffness degradation is insignificant. The elastic-plastic inter-story deformation capacity is high. Compared with the reinforced concrete frame with irregular section columns, the ductility and energy dissipation of the structure are better. The conclusions can be referred to for seismic design of this new kind of structure.

Experimental and Theoretical Studies of Bidirectional Variable Curvature Friction Pendulum Bearing

Shu-Chao Lin,Jian-Qiang Han,Hong-tie Zhao 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.5

In this study, to satisfy the base isolation demand of large-scale building structures under different earthquake records, a new bidirectional variable curvature friction pendulum bearing (BD-VCFPB) is proposed. The VCFPB is designed in detail based on the basic principle of a friction pendulum system. Moreover, the sliding interface function, gap between the slider and the sliding interface, and polytetrafluoroethylene (PTFE) plate stress are studied. Finally, a dynamic cyclic test is conducted to study the influence of the slider size, contact pressure on the PTFE plate, and loading frequency on the hysteretic behavior of the VCFPB. The results indicate that the hysteretic curves of the horizontal force and the displacement are regular, symmetrical, stable, and full, and clearly reflect the variable curvature convex and concave characteristics and the excellent behavior of energy dissipation of the BD-VCFPB. The sliding friction coefficient varies significantly with the contact pressure on the PTFE plate and the loading frequency; however, it has little relation with the slider size. A hysteretic model is proposed based on the results of a unidirectional test, and it is in good agreement with the hysteretic curves of the horizontal force and the displacement from a bidirectional test.

Analysis on Extension Length of Shape Steel in Transfer Columns of SRC–RC Hybrid Structures

Kai Wu,Jianyang Xue,Yang Nan,Hong-tie Zhao 한국강구조학회 2018 International Journal of Steel Structures Vol.18 No.3

Seismic performance of SRC–RC transfer column was analyzed based on the experiment of 16 transfer columns specimens under low cyclic reversed loading, which mainly focus on the extension length of shape steel. Analysis of ductility, bearing capacity, energy dissipation capacity and degeneration ratio of strength were completed. Displacement ductility promotes at fi rst and then reduces with increasing of extension length of shape steel, reaching the peak value when extension length gets close to three fi fths of column height. Extension length of shape steel has little eff ect on bearing capacity, while energy dissipation capacity of transfer columns is infl uenced by many factors. Three fi fths of column height is the rational extension length of shape steel, of which specimens have advanced in energy dissipation, good stability of stiff ness and strength. The bond performance between concrete and shape steel decreases with the increasing of extension length of shape steel, and hence the stability of strength decreases. Minimum extension length of shape steel was confi rmed and the calculation method was proposed, which is mainly used to ensure the bend yielding of shape steel at bottom section. Moment at the truncation section leads to pull-out eff ect of steel bars, which enhances with increasing of the moment and section ratio of shape steel. Contrafl exure point is at three fi fths of column height. If the shape steel extends to contrafl exure point, moment of steel truncation section will reach minimum. So the reduce the concrete damage with better deformation ability and mechanical behavior of transfer column.

Experimental study on Chinese ancient timber-frame building by shaking table test

Xi-cheng Zhang,Jian-yang Xue,Hong-tie Zhao,Yan Sui 국제구조공학회 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.40 No.4

A one-story, wooden-frame, intermediate-bay model with Dou-Gon designed according to the Building Standards of the Song Dynasty (A.D.960-1279), was tested on a unidirectional shaking table. The main objectives of this experimental study were to investigate the seismic performance of Chinese historic wooden structure under various base input intensities. El Centro wave (N-S), Taft wave and Lanzhou wave were selected as input excitations. 27 seismic geophones were instrumented to measure the real-time displacement, velocity and acceleration respectively. Dynamic characteristics, failure mode and hysteretic energy dissipation performance of the model are analyzed. Test results indicate that the nature period and damping ratio of the model increase with the increasing magnitude of earthquake excitation. The nature period of the model is within 0.5~0.6 s, the damping ratio is 3~4%. The maximum acceleration dynamic magnification factor is less than 1 and decreases as the input seismic power increases. The frictional slippage of Dou-Gon layers (corbel brackets) between beams and plates dissipates a certain amount of seismic energy, and so does the slippage between posts and plinths. The mortise-tenon joint of the timber frame dissipates most of the seismic energy. Therefore, it plays a significant part in shock absorption and isolation.