Structural evaluation of a foldable cable-strut structure for kinematic roofs

Jianguo Cai,Qian Zhang,Yiqun Zhang,Daniel Sang-hoon Lee,Jianfeng Zhao 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.29 No.5

The rapidly decreasing natural resources and the global variation of the climate push us to find intelligent and efficient structural systems to provide more people with fewer resources. This paper proposed a kinematic cable-strut system to realize sustainable structures in responding to changing environmental conditions. At first, the concept of the kinematic system based on crystal-cell pyramid (CP) cable-strut unit was given. Then the deployment of the structure was studied experimentally. After that, the static behaviors in the fully deployed state under the symmetric and asymmetric load cases were investigated. Moreover, the effects of thermal loading and the initial prestress distribution were also discussed. Comparative studies between the proposed structure and other deployable cable-strut system under three times of design load cases were carried out. Finally, the robustness of the system was studied by removal of one passive cable at one time.

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.

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.

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.

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.

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.

Biotransformation and detoxification of aflatoxin B₁ by extracellular extract of Cladosporium uredinicola

Shao, Shuai,Cai, Jun,Du, Xin,Wang, ChangGao,Lin, JianGuo,Dai, Jun 한국식품과학회 2016 Food Science and Biotechnology Vol.25 No.6

Aflatoxin contamination of food and grain poses a serious economic and health problem globally. Aflatoxin $B_1$ ($AFB_1$) is extremely mutagenic and toxic as well as a potent carcinogen to both humans and livestock. In this study, the degradation of $AFB_1$ by extracellular extract of Cladosporium uredinicola was examined using high-performance liquid chromatography (HPLC), thin-layer chromatography (TLC), and liquid chromatography mass spectrometry. Within 24 h of incubation, $AFB_1$ was efficiently eliminated by the culture supernatant of C. uredinicola ($84.5{\pm}5.7%$) at $37^{\circ}C$; the elimination was proven to be enzymatic, and the enzyme was thermostable. The biotransformation products of $AFB_1$ detected by HPLC and TLC were proven to be the same compound. Analysis with LCMS showed that $AFB_1$ was bio-transformed to a structurally different compound ($m/z=365[M+Na]^+$), which is first reported. The cytotoxicity study to HeLa cells indicated that culture supernatant-treated $AFB_1$ is less toxic as compared with $AFB_1$.

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.

Purification and characterization of exo-polygalacturonase from Zygoascus hellenicus V25 and its potential application in fruit juice clarification

Xiaohua Lu,Jianguo Lin,Changgao Wang,Xin Du,Jun Cai 한국식품과학회 2016 Food Science and Biotechnology Vol.25 No.5

The purification and characterization of the extracellular polygalacturonase from Zygoascus hellenicus V25 submerged culture using orange peel waste were investigated. This polygalacturonase, with a molecular weight of 75.28 kDa, was purified to 16.89 purification fold with a recovery of 18.46% and specific activity of 2469.77 U/mg protein by ammonium sulfate precipitation, DEAE cellulose chromatography, and Sephadex G-100 gel filtration. The enzyme exhibited maximum activity at 60oC and pH 5.0 and was stable over a wide range of pH levels (3.0-11.0). Moreover, enzyme activity was enhanced by Cu2+ and cysteine, whereas it was strongly inhibited by Hg2+. The extent of enzymatic hydrolysis was negatively correlated with the degree of pectin esterification. Km and Vmax values of the polygalacturonase were 5.44 mg/mL and 61.73 μmol/(min·mg), respectively. The polygalacturonase was applied in the juice clarification of four fruits, and results showed that the percentage transmittance at 660 nm increased by 3.51, 4.36, 8.04, and 12.2%.

Biotransformation and detoxification of aflatoxin B1 by extracellular extract of Cladosporium uredinicola

Shuai Shao,Jun Cai,Xin Du,Changgao Wang,Jianguo Lin,Jun Dai 한국식품과학회 2016 Food Science and Biotechnology Vol.25 No.6

Aflatoxin contamination of food and grain poses a serious economic and health problem globally. Aflatoxin B1 (AFB1) is extremely mutagenic and toxic as well as a potent carcinogen to both humans and livestock. In this study, the degradation of AFB1 by extracellular extract of Cladosporium uredinicola was examined using high-performance liquid chromatography (HPLC), thin-layer chromatography (TLC), and liquid chromatography mass spectrometry. Within 24 h of incubation, AFB1 was efficiently eliminated by the culture supernatant of C. uredinicola (84.5±5.7%) at 37oC; the elimination was proven to be enzymatic, and the enzyme was thermostable. The biotransformation products of AFB1 detected by HPLC and TLC were proven to be the same compound. Analysis with LCMS showed that AFB1 was bio-transformed to a structurally different compound (m/z=365 [M+Na]+), which is first reported. The cytotoxicity study to HeLa cells indicated that culture supernatant-treated AFB1 is less toxic as compared with AFB1.