Chloride Ion Invasive Behavior of Recycled Aggregate Concrete under Coupling Flexural Loading and Wetting-Drying Cycles

Guoliang Bai,Chao Zhu,Chao Liu,Huawei Liu 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.10

In this paper, the invasive behavior of chloride ion has been investigated under the coupling action of wetting-drying cycles and flexural load on recycled aggregate concrete (RAC) beams in sodium chloride solution. The permeation properties of chloride in RAC were studied by analyzing the content, binding capacity and diffusion coefficient of chloride. The priority of interfacial transition zone (ITZ) for chloride transport in RAC was analyzed by energy dispersive spectrometer (EDS). Additionally, the distribution of chloride content in concrete was predicted. The results indicated that the micro-pore structure, initial damage and micro-cracks provide more paths for the diffusion of chloride in the RAC. The binding capacity of chloride diminished with the incorporation of recycled coarse aggregate (RCA) and the exertion of flexural load, which increased the chloride diffusion coefficient. The correctness of Fick's second diffusion law was verified via applying it to the data processing. Furthermore, the convection and diffusion zones had the significant influence on the distribution of chloride.

Parametric analysis on diagonal bracing joints connected with self-tapping screw

Zhenhua Xu,Guoliang Bai,Biao Liu,Jiarui Li,Yifan Yang 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.41 No.1

In this paper, a three-dimensional finite element model (FEM) was established to study the performance of sliding resistance on the diagonal bracing joints of prefabricated steel frame (PSF) connected with self-tapping screw. In addition, the load-displacement curves of the joints were well verified by the test results, and a parametric study was conducted using the validated models to investigate the effect of steel grade, thickness of the tapped plate, the margin of bolt hole, the end and the central distance of bolt hole. The results showed that with the increase of steel grade, thickness of the tapped plate and the distance of the bolt holes, the anti-slide stiffness and the ultimate bearing capacity of the joint were significantly improved. It was recommended that steel grade should be Q345, Q390 or above. It was advisable to take the thickness of the tapped plate at 0.7d0 ~ 1.0d0, take the margin of bolt hole at 1.2d0 ~ 1.6d0, the central and the end distance of bolt hole should be greater than 2.0d0 and 1.2d0, respectively. The results could provide reference for engineering design.

Functional Analysis of Wheat TaPaO1 Gene Conferring Pollen Sterility Under Low Temperature

Changping Zhao,Guoliang Yuan,Yukun Wang,Shaohua Yuan,Peng Wang,Wenjing Duan,Jianfang Bai,Hui Sun,Na Wang,Fengting Zhang,Liping Zhang 한국식물학회 2018 Journal of Plant Biology Vol.61 No.1

Thermosensitive male sterility plays an important role in wheat fertility and production. As a key enzyme for chlorophyll degradation, pheophorbide a oxygenase (PaO) can suppress cell death in plants. We cloned the wheat gene TaPaO1 from the thermosensitive genetic male sterile (TGMS) line BS366; it encodes a typical PaO protein, containing a conserved Rieske [2Fe-2S] iron–sulphur motif, a mononuclear non-heme iron-binding motif, and a C-terminal CxxC motif. TaPaO1 was expressed in all tissues and was upregulated during the meiosis stage of BS366 anthers under low temperature. Subcellular localization of TaPaO1 specifically labelled the surrounding of chloroplasts. TaPaO1 regulated by RD29A promoter which responded to low temperature led to pollen sterility in transgenic tobacco. Expression analysis showed that TaPaO1 exhibited a higher level of expression in the anther than in other tissues in transgenic tobacco plants during low temperature treatment. We propose that the higher senescence-related activity of TaPaO1 may lead to the cell death of anthers, which happens at an early developmental stage under low temperature. These results provide new insights into the function of PaO during the early developmental stage of anthers. PaO is closely related to cell death regardless of whether it exhibits increased activity or inactive.

Experimental study on seismic behavior of high strength reinforced concrete frame columns with high axial compression ratios

Guojun Zhang,Jianxin Liu,Guoliang Bai,Boquan Liu 국제구조공학회 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.33 No.5

Experimental study on seismic behavior of high strength reinforced concrete frame columns with high axial compression ratios

Zhang, Guojun,Liu, Boquan,Bai, Guoliang,Liu, Jianxin Techno-Press 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.33 No.5

Shaking Table Test on Seismic Responses of a Monolithic Precast Concrete Shear Wall Structure

Chao-gang Qin,Guoliang Bai,Ya-zhou Xu,Ning Fen Su,Tao Wu,Zhong Liang Li,Yu Zhe Sun 대한토목학회 2018 KSCE Journal of Civil Engineering Vol.22 No.10

To examine the seismic performance of Monolithic Precast Concrete Shear Wall (MPCSW) structure, a 1/5-scaled twelve-story model is designed and investigated by shaking table test, and connections between the precast elements and their impact on seismic performance of the overall model are comprehensively inspected and analyzed. Based on the testing results, the structural responses are divided into elastic stage and plastic stage, and the variations of dynamic characteristics, cracking and failure pattern, seismic responses of the model are accordingly presented. The experimental results indicate that most of critical cracks of the MPCSW model locate on the coupling beams and horizontal connections of precast concrete shear walls, and the fundamental frequency exhibits a successively decreasing trend during the entire testing process. Furthermore, The MPCSW model is designed in accordance with Chinese codes meets the requirement for the seismic fortification intensity of eight, and shows an adequate safety margin to resist collapse in the case of 0.90 g.

Experimental research on design wind loads of a large air-cooling structure

Xu Yazhou,Ren Qianqian,Bai Guoliang,Li Hongxing 한국풍공학회 2019 Wind and Structures, An International Journal (WAS Vol.28 No.4

Because of the particularity and complexity of direct air-cooling structures (ACS), wind parameters given in the general load codes are not suitable for the wind-resistant design. In order to investigate the wind loads of ACS, two 1/150 scaled three-span models were designed and fabricated, corresponding to a rigid model and an aero-elastic model, and wind tunnel tests were then carried out. The model used for testing the wind pressure distribution of the ACS was defined as the rigid model in this paper, and the stiffness of which was higher than that of the aero-elastic model. By testing the rigid model, the wind pressure distribution of the ACS model was studied, the shape coefficients of “A” shaped frame and windbreak walls, and the gust factor of the windbreak walls were determined. Through testing the aero-elastic model, the wind-induced dynamic responses of the ACS model was studied, and the wind vibration coefficients of ACS were determined based on the experimental displacement responses. The factors including wind direction angle and rotation of fan were taken into account in this test. The results indicated that the influence of running fans could be ignored in the structural design of ACS, and the wind direction angle had a certain effect on the parameters. Moreover, the shielding effect of windbreak walls induced that wind loads of the “A” shaped frame were all suction. Subsequently, based on the design formula of wind loads in accordance with the Chinese load code, the corresponding parameters were presented as a reference for wind-resistant design and wind load calculation of air-cooling structures.

Study on Calculation Method of Long Term Deformation of RAC Beam based on Creep Adjustment Coefficient

Chao Liu,Zhenyuan Lv,Chao Zhu,Guoliang Bai,Yu Zhang 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.1

The creep shrinkage of concrete is an important factor in the long-term deformation of concrete structures. It is also a key link for solving long-term deformation calculation accuracy and complex calculation forms. In this paper, a 1200-day long-term deformation test was conducted on beams with 0%, 50%, and 100% substitution ratios of recycled coarse aggregate. Meanwhile, based on the principle of virtual work, the creep coefficient of recycled concrete is introduced into the calculation of additional curvature of the beam section, and the formula for calculating the long-term deformation of recycled concrete is established. According to the size of recycled coarse aggregate, through the calculation of creep and shrinkage of concrete, the regeneration adjustment coefficient of concrete creep and shrinkage, the calculation results into three typical model of ordinary concrete creep and shrinkage, creep and shrinkage of concrete and regeneration model of deformation calculation of long period, the calculated and experimental results agree well; based on this, the deflection increase coefficient is proposed, which simplifies the long-term calculation formula. It not only can meet the calculation accuracy requirements, but also can be easily adapted to engineering promotion.

Experimental Study on Bond Behavior between Section Steel and RAC under Full Replacement Ratio

Chao Liu,Ziyu Fan,Xiaona Chen,Chao Zhu,Haiyang Wang,Guoliang Bai 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.3

Nine specimens of steel reinforced recycled concrete are designed to explore the effect of four factors as the cover thickness of section steel, the embedded length of section steel, the recycled aggregate concrete strength, and the lateral stirrup ratio on bond slip between section steel and recycled aggregate concrete. The test results show that the failure modes of recycled aggregate concrete are as similar as normal concrete; three formulas are proposed for the bond stress between section steel and recycled aggregate concrete, which are fitting well. The mathematical model of bond stress-slip is established through analysis, and the predicted curve is close to the test curve. The research results provide the basis for the numerical simulation analysis of the bond slip for the recycled aggregate concrete under the full replacement ratio.

Seismic response of steel reinforced concrete frame-bent plant of CAP1400 nuclear power plant considering the high-mode vibration

Biao Liu,Zhengzhong Wang,Bo Zhang,Ningjun Du,Mingxia Gao,Guoliang Bai 국제구조공학회 2023 Steel and Composite Structures, An International J Vol.46 No.2

In order to study the seismic response of the main plant of steel reinforced concrete (SRC) structure of the CAP1400 nuclear power plant under the influence of different high-mode vibration, the 1/7 model structure was manufactured and its dynamic characteristics was tested. Secondly, the finite element model of SRC frame-bent structure was established, the seismic response was analyzed by mode-superposition response spectrum method. Taking the combination result of the 500 vibration modes as the standard, the error of the base reactions, inter-story drift, bending moment and shear of different modes were calculated. Then, based on the results, the influence of high-mode vibration on the seismic response of the SRC frame-bent structure of the main plant was analyzed. The results show that when the 34 vibration modes were intercepted, the mass participation coefficient of the vertical and horizontal vibration mode was above 90%, which can meet the requirements of design code. There is a large error between the seismic response calculated by the 34 and 500 vibration modes, and the error decreases as the number of modes increases. When 60 modes were selected, the error can be reduced to about 1%. The error of the maximum bottom moment of the bottom column appeared in the position of the bent column. Finally, according to the characteristics of the seismic influence coefficient αj of each mode, the mode contribution coefficient γj•Xji was defined to reflect the contribution of each mode to the seismic action.