Failure Pattern of Singe-layer Reticulated Dome under Severe Earthquake and Its Shaking Table Test

Gui-Bo Nie,Xudong Zhi,Feng Fan,Jun-Wu Dai 한국강구조학회 2014 International Journal of Steel Structures Vol.14 No.2

Based on the constitutive model with considering material damage accumulation, the influence of material damageaccumulation on the responses of the structure is investigated in detail through the incremental dynamic analysis method (IDAanalysis). The failure pattern of single-layer reticulated dome under dynamic loading is obtained using IDA analysis throughmultiple sets of seismic load records and harmonic loading, which is identified to be the dynamic instability failure caused bythe geometric nonlinearity and the dynamic strength failure resulted by the material nonlinearity. The shaking table tests ofsingle-layer reticulated dome are exploited to verify the failure pattern of the structure under seismic load records. Experimentalresults show that the plasticity of the model develops and the deformation increases, as well as the mechanical propertiesweakens continuously with the increasing of the loading value, which indicates that the failure pattern of the structure isdynamic strength failure.

Three-Dimensional Seismic Isolation Study of Single-Layer Reticulated Domes by Parameter Analysis

Gui-Bo Nie,Dong-fang Li,Xudong Zhi,Qiang Chen,Fuyang Wang 한국강구조학회 2021 International Journal of Steel Structures Vol.21 No.6

Spatial structures, represented by reticulated domes, have developed rapidly in the last several decades due to their reasonable mechanical properties and beautiful structural shape. However, several spatial structure collapses have occurred during the recent frequent earthquakes in China, especially the 2013 Lushan earthquake. These collapses have altered the traditional understanding that the spatial structure has good seismic performance. Real seismic damage cases reveal that a spatial structure in a severe earthquake zone with unreasonable seismic design cannot maintain its functional characteristics; therefore, there is an urgent need for improvements to enhance the seismic performance of spatial structures. This paper proposes a new three-dimensional isolation spring support (TISS). To study the mechanical properties of this support, corresponding experiments were performed, and the constitutive relation of this support was investigated. A simplifi ed fi nite element model of the new TISS was defi ned in ABAQUS to conduct a seismic isolation study of single-layer reticulated domes. And then the infl uence of diff erent parameters on the seismic isolation performance of the TISS was analysed. The parameter analysis results indicated that friction plays an important role in the mechanical properties of the support and thus causes diff erent seismic isolation eff ects under small earthquakes and severe earthquakes. At the same time, because of the design concept of the support, a non-linear relation exists between the seismic isolation eff ect and stiff ness such that under severe earthquakes. On the other hand, the TISS also has preferable isolation performance on the defective reticulated domes. Therefore, the three-dimensional isolation support presented in this paper has preferable application prospects and potential economic benefi ts that could be applied extensively in the three-dimensional isolation area of spatial structures. In addition, the numerical analysis procedure based on ABAQUS can be used to accurately analyse the isolation property and to lay the foundation for the practical function of isolation supports and the seismic design of structures.

Study on Dynamic Behavior of Single-Layer Reticulated Dome by Shaking Table Test

Gui-bo Nie,Xing-long Zhu,Xudong Zhi,Fuyang Wang,Jun-Wu Dai 한국강구조학회 2018 International Journal of Steel Structures Vol.18 No.2

Large-span space structures in the form of reticulated domes, which have developed rapidly in the last three decades, are widely used in large-scale public buildings . In order to have a better understanding of its mechanical performance and verify the failure pattern under seismic motion, a shaking table test of a single-layer reticulated dome was carried out. The geometric position of the structural nodes and material properties of the members were measured, such as yield strength and Young’s modulus . The dynamic characterization of the model under white-noise excitation and fast size frequency was then performed to obtain its natural vibration frequency and damping factor. Next, the mechanical performance of the model under weak and strong seismic motions was investigated experimentally. Finally, a comparison between the experimental and numerical results obtained using the fi nite element software ABAQUS was made and a satisfactory agreement was found. The occurrence of large-scale deformation and signifi cant material plasticity of these structures under severe seismic motion can be regarded as indicators of dynamic strength failure. This is the fi rst time that the pattern of dynamic strength failure has been observed via shaking table tests.

A Damage Constitutive Model of Q345B Steel in Circular Tubes Based on Cyclic Experiments and Its Application on Structure

Gui-bo Nie,Chenxiao Zhang,Xudong Zhi,Kun Liu,Huihuan Ma 한국강구조학회 2019 International Journal of Steel Structures Vol.19 No.2

Q235B and Q345B are two structural steel grades widely used in China. In previous studies, more precisely in 2012, Nie defi ned a normalized constitutive model using material damage accumulation to describe damage behavior of Q235B steel in circular tubes. This paper focuses on the hysteretic damage behavior of Q345B steel in a circular steel tube under cyclic loads and describes the damage mechanism through a damage constitutive model based on experimental results. Three equations are implemented in the constitutive model, which includes a damage index to accurately describe the plastic and damage behavior of the material. Experiments were conducted in which a cyclic loading is applied in three directions on a circular steel tube. The constitutive model was implemented in the ABAQUS FEA software through a user-defi ned subroutine. Some parameters in the constitutive model were calibrated based on the experimental and numerical results. The performance behavior of a single-layer reticulated dome under seismic motion record was investigated through the increment dynamic analysis method. The results indicate that the constitutive model is suitable for analyses and quantifying seismic damage accumulation and progressive failure and it is also benefi cial for investigating the nonlinear dynamic behavior of structures under seismic loads. The eff ect of accumulated material damage can describe large-scale structural deformation and obvious reduction in the failure limit load.

Shaking Table Study of the Three-Dimensional Isolation of a Cylindrical Reticulated Shell

Gui-bo Nie,Chenxiao Zhang,Zhi-yong Wang,Yu-jie Shi 한국강구조학회 2022 International Journal of Steel Structures Vol.22 No.2

A set of shaking table tests were conducted to investigate the dynamic response characteristics of a single-layer cylindrical reticulated shell (SLCRS) with three-dimensional column-top seismic isolation. The infl uence of infi lled wall on the seismic and isolation performance of the structure was investigated. The dynamic response characteristics of structures with and without seismic isolation were compared to investigate the eff ects of seismic isolation. The dynamic responses of lower-frame models with and without an infi lled wall were also compared to investigate the eff ects of the infi lled wall on the seismic isolation. Results show that the three-dimensional column-top seismic isolation improved the seismic safety of infi lled wall. At the same time, the three-dimensional column-top isolation bearing can signifi cantly reduce the acceleration and stress of the structure. The excellent isolation performance of the three-dimensional isolation bearing promises outstanding application prospects for this isolation bearing in highly seismic areas. In addition, under a small earthquake, the acceleration of the second fl oor with the isolation bearing was unfavorably magnifi ed. Therefore, the seismic performance of the acceleration-sensitive nonstructural components should be improved when the three-dimensional column-top seismic isolation is applied in the areas of low seismicity. The test data and conclusions obtained in the present study can provide theoretical and technical support for the actual engineering application of such three-dimensional seismic isolation bearings.

Seismic Isolation Research on a Double-Layer lattice Structure Using Shaking Table Tests

Chenxiao Zhang,Gui-bo Nie,Jun-Wu Dai,Kun Liu,Xudong Zhi,Huihuan Ma 한국강구조학회 2019 International Journal of Steel Structures Vol.19 No.4

Typical failure patterns of members, supports, and joints were observed in double-layer lattice space structures during the 2013 M7.0 Lushan earthquake in the Sichuan province of China. Various isolation supports have been implemented in recent years to enhance the structural performance by reducing the dynamic responses. However, these isolation supports mostly focus on either horizontal isolation or vertical isolation, which is not applicable for synchronous isolation in both horizontal and vertical directions. Therefore, an innovative isolated support used for three-dimensional isolation was invented. In order to verify the feasibility of using the isolated support to reduce the earthquake response of double-layer lattice structures under small to strong earthquakes, a scale model was subjected to a shaking-table test before and after application of the isolated support. The dynamic characteristics, earthquake performance and failure pattern of the model with and without the isolated supports are discussed based on the earthquake responses, including acceleration, displacement, and strain. Results of the test indicate that the earthquake eff ect is underestimated without regard to the dynamic amplifi cation eff ect of the lower supporting reinforced concrete structures, which led to the failure of the structure. The compared experimental results indicate that the isolated supports had remarkable earthquake isolation and reduction in both the horizontal and vertical directions.