Research on the Carbonation Resistance and Carbonation Depth Prediction Model of Fly Ash- and Slag-Based Geopolymer Concrete

Chenggong Zhao,Jian Li,Zhenyu Zhu,Qiuyu Guo,Xinrui Wu,Zhiyuan Wang,Renda Zhao 대한토목학회 2024 KSCE Journal of Civil Engineering Vol.28 No.7

To study the effect of different slag content and different curing methods on the carbonation resistance of fly ash- and slag-based geopolymer concrete (FA&SL-GPC), a series of experiments were carried out with slag content (accounting for 10%, 30% and 50% of cementitious materials) and curing methods (standard curing and high temperature curing) as variables. The results show that increasing the slag content is helpful for improving the carbonation resistance properties, microstructure, and carbonation resistance components of FA&SL-GPC substrate. Adopting a standard curing method and prolonging the curing age are more favorable to the carbonation resistance of FA&SL-GPC, and the longer the curing time is, the better. Finally, the carbonation depth prediction model suitable for this experiment is deduced and verified. From the research results, it can be seen that using a high slag content mix and curing under standard conditions is beneficial for the carbonization resistance of GPC structural components.

Experimental and finite element studies of special-shape arch bridge for self-balance

Lu, Pengzhen,Zhao, Renda,Zhang, Junping Techno-Press 2010 Structural Engineering and Mechanics, An Int'l Jou Vol.35 No.1

Special-shape arch bridge for self-balance (SBSSAB) in Zhongshan City is a kind of new fashioned spatial combined arch bridge composed of inclined steel arch ribs, curved steel box girder and inclined suspenders, and the mechanical behavior of the SBSSAB is particularly complicated. The SBSSAB is aesthetic in appearance, and design of the SBSSAB is artful and particular. In order to roundly investigate the mechanical behavior of the SBSSAB, 3-D finite element models for spatial member and shell were established to analyze the mechanical properties of the SBSSAB using ANSYS. Finite element analyses were conducted under several main loading cases, moreover deformation and strain values for control section of the SBSSAB under several main loading cases were proposed. To ensure the safety and rationality for optimal design of the SBSSAB and also to verify the reliability of its design and calculation theories, the 1/10 scale model tests were carried out. The measured results include the load checking calculation, lane loading and crowd load, and dead load. A good agreement is achieved between the experimental and analytical results. Both experimental and analytical results have shown that the SBSSAB is in the elastic state under the planned test loads, which indicates that the SBSSAB has an adequate load-capacity. The calibrated finite-element model that reflects the as-built conditions can be used as a baseline for health monitoring and future maintenance of the SBSSAB.

A new analytical method for deformation of composite steel-concrete straight box girders with interfacial slip

Pengzhen Lu,Renda Zhao 국제구조공학회 2010 Structural Engineering and Mechanics, An Int'l Jou Vol.34 No.6

A new analytical method for deformation of composite steel-concrete straight box girders with interfacial slip

Lu, Pengzhen,Zhao, Renda Techno-Press 2010 Structural Engineering and Mechanics, An Int'l Jou Vol.34 No.6

Experimental and finite element studies of special-shape arch bridge for self-balance

Pengzhen Lu,Renda Zhao,Junping Zhang 국제구조공학회 2010 Structural Engineering and Mechanics, An Int'l Jou Vol.35 No.1

Special-shape arch bridge for self-balance (SBSSAB) in Zhongshan City is a kind of new fashioned spatial combined arch bridge composed of inclined steel arch ribs, curved steel box girder and inclined suspenders, and the mechanical behavior of the SBSSAB is particularly complicated. The SBSSAB is aesthetic in appearance, and design of the SBSSAB is artful and particular. In order to roundly investigate the mechanical behavior of the SBSSAB, 3-D finite element models for spatial member and shell were established to analyze the mechanical properties of the SBSSAB using ANSYS. Finite element analyses were conducted under several main loading cases, moreover deformation and strain values for control section of the SBSSAB under several main loading cases were proposed. To ensure the safety and rationality for optimal design of the SBSSAB and also to verify the reliability of its design and calculation theories, the 1/10 scale model tests were carried out. The measured results include the load checking calculation, lane loading and crowd load, and dead load. A good agreement is achieved between the experimental and analytical results. Both experimental and analytical results have shown that the SBSSAB is in the elastic state under the planned test loads, which indicates that the SBSSAB has an adequate load-capacity. The calibrated finite-element model that reflects the as-built conditions can be used as a baseline for health monitoring and future maintenance of the SBSSAB.

Dynamic interaction analysis of vehicle-bridge system using transfer matrix method

Tianyu Xiang,Renda Zhao 국제구조공학회 2005 Structural Engineering and Mechanics, An Int'l Jou Vol.20 No.1

The dynamic interaction of vehicle-bridge is studied by using transfer matrix method in this paper. The vehicle model is simplified as a spring-damping-mass system. By adopting the idea of Newmark-β method, the partial differential equation of structure vibration is transformed into a differential equation irrelevant to time. Then, this differential equation is solved by transfer matrix method. The prospective application of this method in real engineering is finally demonstrated by several examples.

Dynamic interaction analysis of vehicle-bridge system using transfer matrix method

Xiang, Tianyu,Zhao, Renda Techno-Press 2005 Structural Engineering and Mechanics, An Int'l Jou Vol.20 No.1

The dynamic interaction of vehicle-bridge is studied by using transfer matrix method in this paper. The vehicle model is simplified as a spring-damping-mass system. By adopting the idea of Newmark-${\beta}$ method, the partial differential equation of structure vibration is transformed into a differential equation irrelevant to time. Then, this differential equation is solved by transfer matrix method. The prospective application of this method in real engineering is finally demonstrated by several examples.

Experimental Study on Time-dependent Behavior of Concrete Filled Steel Tubes in Ambient Environment

Yongbao Wang,Renda Zhao 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.1

The time-dependent behavior of Concrete Filled Steel Tubes (CFST) is greatly influenced by concrete creep and shrinkage. The temperatures in ambient environment would accelerate or decrease this process. However, influence of temperatures on timedependent behavior was not considered in the references. In this paper, the shrinkage and creep tests of plain concrete and CFST in ambient environment was carried out. And CEB10 model was modified to fit to all the test results of plain concrete. Based on Age- Adjusted Elastic Modulus (AAEM) method and step-by-step method, the numerical model to calculate the time-dependent behavior of CFST considering the confining stress effect was established and compared with the methods reported in the literatures. The parametric study was conducted based on the creep models considering temperatures effect and formulas developed in this paper. The creep coefficient ratios between CFST and plain concrete in ambient conditions were carried out. The analyses have shown that the fully bond assumption between the core concrete and steel tube is valid. The proposed methods can be used to calculate the timedependent behavior of CFST accurately. Parametric analysis demonstrates that the CEB10 model considering the temperature effect has more effectiveness than other creep models used in calculating creep of CFST. Additionally, the ratios of creep coefficients between concrete and CFST are in the range of 0.2−0.6. It indicated that the time-dependent behavior of CFST influenced by temperatures should be given more attention.

Nonlinear finite element analysis of circular concrete-filled steel tube structures

Xu, Tengfei,Xiang, Tianyu,Zhao, Renda,Zhan, Yulin Techno-Press 2010 Structural Engineering and Mechanics, An Int'l Jou Vol.35 No.3

The structural behaviors of circular concrete filled steel tube (CFT) structures are investigated by nonlinear finite element method. An efficient three-dimensional (3D) degenerated beam element is adopted. Based on those previous studies, a modified stress-strain relationship for confined concrete which introduces the influence of eccentricity on confining stress is presented. Updated Lagrange formulation is used to consider the geometrical nonlinearity induced by large deformation effect. The nonlinear behaviors of CFT structures are investigated, and the accuracy of the proposed constitutive model for confined concrete is mainly concerned. The results demonstrate that the confining effect in CFT elements subjected to combining action of axial force and bending moment is far sophisticated than that in axial loaded columns, and an appropriate evaluation about this effect may be important for nonlinear numerical simulation of CFT structures.

Nonlinear finite element analysis of circular concrete-filled steel tube structures

Tengfei Xu,Tianyu Xiang,Renda Zhao,Yulin Zhan 국제구조공학회 2010 Structural Engineering and Mechanics, An Int'l Jou Vol.35 No.3

The structural behaviors of circular concrete filled steel tube (CFT) structures are investigated by nonlinear finite element method. An efficient three-dimensional (3D) degenerated beam element is adopted. Based on those previous studies, a modified stress-strain relationship for confined concrete which introduces the influence of eccentricity on confining stress is presented. Updated Lagrange formulation is used to consider the geometrical nonlinearity induced by large deformation effect. The nonlinear behaviors of CFT structures are investigated, and the accuracy of the proposed constitutive model for confined concrete is mainly concerned. The results demonstrate that the confining effect in CFT elements subjected to combining action of axial force and bending moment is far sophisticated than that in axial loaded columns, and an appropriate evaluation about this effect may be important for nonlinear numerical simulation of CFT structures.