New Failure Mechanism for Evaluating the Static and Seismic Ultimate Bearing Capacity of Strip Footings Adjacent to Slope

Hongwei Fang,Yixiang Xu,Guowen Xu 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.5

The seismic slip line field theory (SLFT) is derived based on the method of characteristic, and the critical slope contour calculated by the SLFT is a convex shape when a high surcharge is imposed on the slope top surface. A simple and robustness failure mechanism is proposed to calculate the static and seismic ultimate bearing capacity of strip footing adjacent to the cohesion-frictional slopes where the critical slope contour shifts from the inside of the slope to the outside of the slope with the increase of the boundary load, and the slope is at the limit state when the critical slope contour is tangent to the slope surface. The influence of slope and footing geometric features, soil parameters, and the seismic load on the bearing capacity is analyzed. The ultimate bearing capacity decreases as the strength parameters decreases, and the slope angle and the seismic coefficient increases. The static and seismic bearing capacity calculated by the proposed method does not require the failure models to be initially assumed, and the results are consistent with those of the other methods.

Non-linear stability analysis of a hybrid barrel vault roof

Jianguo Cai,Ya Zhou,Yixiang Xu,Jian Feng 국제구조공학회 2013 Steel and Composite Structures, An International J Vol.14 No.6

This paper focuses on the buckling capacity of a hybrid grid shell. The eigenvalue buckling, geometrical non-linear elastic buckling and elasto-plastic buckling analyses of the hybrid structure were carried out. Then the influences of the shape and scale of imperfections on the elasto-plastic buckling loads were discussed. Also, the effects of different structural parameters, such as the rise-to-span ratio, beam section, area and pre-stress of cables and boundary conditions, on the failure load were investigated. Based on the comparison between elastic and elasto-plastic buckling loads, the effect of material non-linearity on the stability of the hybrid barrel vault is found significant. Furthermore, the stability of a hybrid barrel vault is sensitive to the anti-symmetrical distribution of loads. It is also shown that the structures are highly imperfection sensitive which can greatly reduce their failure loads. The results also show that the support conditions pose significant effect on the elasto-plastic buckling load of a perfect hybrid structure.

On Fundamental Concepts and Legal System Construction of Carbon Emission Trading Regulation in China

LIU JUNYU(유준우),XU YIXIANG(서의상) 동아대학교 법학연구소 2024 國際去來와 法 Vol.- No.45

탄소시장이 날로 활성화되고 탄소거래 메커니즘이 지속적으로 개선됨에 따라 탄소배출거래에 대한 법적 규제문제는 중국의 “탄소피크탄소중립” 전략 구현의 중점과 난점이 되었다. 첫째, 수직적 권한분배의 관점에서 중국의 탄소배출권 거래규제는 “중앙결정, 지방집행(中央决定、地方执行)”의 논리를 나타내며, 입법에서 “권리와 책임의 불명확”과 “권리와 책임의 공동부담”현상을 초래하기 쉽다; 둘째, 탄소배출권거래 규제의 입법에서 중앙과 지방의 입법권은 불분명하기 때문에 입법권의 중첩, 남용과 혼란을 초래하여 중앙과 지방 각각의 규제역할의 발휘를 저해한다. 중국의 탄소배출권거래 규제의 수평적 권한 분배에서 보면 단일 규제의 문제를 나타낸다. 본 글은 탄소배출거래권 법적 규제의 기본이념에 입각하여 종합적인 입법모델을 적용하여 규제하고 탄소배출거래권 규제 입법을 기후변화 입법의 프레임워크에 포함시킬 것을 주장한다. 탄소배출거래 규제목표를 명확히 하는 기반으로 탄소배출거래 규제주체의 다원적 공동관리를 명확히 하고, 탄소배출거래권 인센티브규제의 규칙체계를 보완하며, 탄소배출거래 정보감독관리를 규범화하여 중국 탄소배출거래권 규제 법제도에 체계화된 해결방안을 제공한다. With the booming of carbon market and continued completion of carbon trading mechanism, the carbon emission trading regulation has become the key issue in the implementation of China’s “carbon peak and neutrality” strategy. With respect to the longitudinal distribution of powers, the carbon emission trading regulation follows the principle of “central decision-making and local implementation”, which can easily result in the problem of “unclear and shared powers and responsibilities” in legislation; besides, the remarkably similar powers of central and local authorities in the legislation for carbon emission trading regulation has led to overlap, abuse and confusion of legislative powers, which further hinder the exertion of self-regulation function by the central and local authorities. On the horizontal distribution of powers, there exists a problem of single regulation in the carbon emission trading regulation. Based on the fundamental concepts of carbon emission trading regulation, this paper proposes to adopt a comprehensive legislation model to implement regulation and incorporate the legislation of carbon emission trading regulation into the framework of climate change legislation. Upon clarification of the targets of carbon emission trading regulation, this paper attempts to provide a systematic solution for the legal system of carbon emission trading regulation in China by identifying the co-governance by multiple regulation entities, completing the incentive-based carbon emission trading regulation system, and standardizing the regulation of carbon emission trading information.

Analysis of key elements of single-layer dome structures against progressive collapse

Qian Zhang,Wenxing Huang,Yixiang Xu,Jianguo Cai,Fang Wang,Jian Feng 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.42 No.2

The analysis of the progressive collapse resistance of structures is a well-known issue among structural engineers. Large-span reticulated dome structures are commonly utilized in large public buildings, necessitating research into their progressive collapse resistance to assure user safety. The most significant part of improving the structural resilience of reticulated domes is to evaluate their key elements. Based on a stiffness-based evaluation approach, this work offers a calculating procedure for element importance coefficient. For both original and damaged structures, evaluations are carried out using the global stiffness matrix and the determinant. The Kiewitt, Schwedler, and Sunflower reticulated domes are investigated to explore the distribution characteristic of element importance coefficients in the single-layer dome structures. Moreover, the influences of the load levels, load distributions, geometric parameters and topological features are also discussed. The results can be regarded as the initial concept design reference for single-layer reticulated domes.

Geometry and Mechanical Behaviour of Radially Retractable Roof Structures During the Movement Process

Jianguo Cai,Yuhang Zhou,Yifeng Zhu,Yixiang Xu,Jin Zhang 한국강구조학회 2016 International Journal of Steel Structures Vol.16 No.3

In this paper, the kinematic characteristic of the radially retractable roof structure was firstly discussed and the motion boundary of the system was also studied. The results show that the diameter of the outer boundary of the system increases firstly and then decreases when the roof is open. Moreover, the numerical study of the structural behavior of the retractable roof with radial foldable bars and circumferential foldable bars was carried out, respectively. It can be found the latter one has a better structural behavior. Then the mechanical behaivor of the system during the motion was also investigated. Finally, a loop linkage based on a special scissor-like element was proposed to support the retractable roof.

Dynamic analysis of a cylindrical boom based on Miura origami

Jianguo Cai,Ya Zhou,Xinyu Wang,Yixiang Xu,Jian Feng 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.28 No.5

The dynamic behavior of the deployment and folding process of a foldable boom based on the Miura origami pattern is investigated in this paper. Firstly, mechanical behavior of a single storey during the motion is studied numerically. Then the deployment and folding of a multi-storey boom is discussed. Moreover, the influence of the geometry parameters and the number of Miura-ori elements n on the dynamic behavior of the boom is also studied. Finally, the influence of the imperfection on the dynamic behavior is investigated. The results show that the angles between the diagonal folds and horizontal folds will have great effect on the strains during the motion. A bistable configuration can be obtained by choosing proper fold angles for a given multi-storey boom. The influence of the imperfection on the folding behavior of the foldable mast is significant.

Nonlinear stability analysis of a radially retractable hybrid grid shell in the closed position

Jianguo Cai,Qian Zhang,Youbao Jiang,Yixiang Xu,Jianfeng Zhao,Xiaowei Deng 국제구조공학회 2017 Steel and Composite Structures, An International J Vol.24 No.3

The buckling capacity of a radially retractable hybrid grid shell in the closed position was investigated in this paper. The geometrically non-linear elastic buckling and elasto-plastic buckling analyses of the hybrid structure were carried out. A parametric study was done to investigate the effects rise-to-span ratio, beam section, area and pre-stress of cables, on the failure load. Also, the influence of the shape and scale of imperfections on the elasto-plastic buckling loads was discussed. The results show that the critical buckling load is reduced by taking account of material non-linearity. Furthermore, increasing the rise-tospan ratio or the cross-section area of steel beams notably improves the stability of the structure. However, the cross section area and pre-stress of cables pose negligible effect on the structural stability. It can also be found that the hybrid structure is highly sensitive to geometric imperfection which will considerably reduce the failure load. The proper shape and scale of the imperfection are also important.

Static analysis of a radially retractable hybrid grid shell in the closed position

Jianguo Cai,Chao Jiang,Xiaowei Deng,Jianfeng Zhao,Yixiang Xu 국제구조공학회 2015 Steel and Composite Structures, An International J Vol.18 No.6

A radially retractable roof structure based on the concept of the hybrid grid shell is proposed in this paper. The single-layer steel trusses of the radially foldable bar structure are diagonally stiffened by cables, which leads to a single-layer lattice shell with triangular mesh. Then comparison between the static behavior between the retractable hybrid grid shell and the corresponding foldable bar shell with quadrangular mesh is discussed. Moreover, the effects of different structural parameters, such as the rise-to-span ratio, the bar cross section area and the pre-stress of the cables, on the structural behaviors are investigated. The results show that prestressed cables can strengthen the foldable bar shell with quadrangular mesh. Higher structural stiffness is anticipated by introducing cables into the hybrid system. When the rise-span ratio is equal to 0.2, where the joint displacement reaches the minimal value, the structure shape of the hyrbid grid shell approaches the reasonable arch axis. The increase of the section of steel bars contributes a lot to the integrity stiffness of the structure. Increasing cable sections would enhance the structure stiffness, but it contributes little to axial forces in structural members. And the level of cable prestress has slight influence on the joint displacements and member forces.

Numerical form-finding of multi-order tensegrity structures by grouping elements

Xinyu Wang,Jianguo Cai,Daniel Sang-hoon Lee,Yixiang Xu,Jian Feng 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.41 No.2

Multi-order tensegrity structures are an attractive form of compliant deployable structures. An efficient numerical form-finding method is proposed for multi-stable tensegrity structures in this paper. The current method first analyze the force density matrix for sets of more feasible force densities that satisfy the non-degeneracy conditions. Then, based on symmetrical grouping of elements, a genetic algorithm is used to minimize the eigenvalues; as a result, multiple orders of equilibrium can be found. For the investigation, two symmetric tensegrity structures are analyzed using the currently proposed method, and the method’s applicability and accuracy have been examined.