Dalian Institute of Building Scientific Research and Design Stock Co.

Dalian, China

Dalian Institute of Building Scientific Research and Design Stock Co.

Dalian, China

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Xu S.,Zhejiang University | Wang N.,Dalian Institute of Building Scientific Research and Design Stock Co. | Yin S.,China University of Mining and Technology
Jianzhu Jiegou Xuebao/Journal of Building Structures | Year: 2011

Nine concrete beams were cast and tested based on a normal steel reinforcement configuration, which included one specimen for comparison without strengthening, five specimens strengthened with post-poured UHTCC and three specimens strengthened with reinforced UHTCC. UHTCC material was poured on local bending face of the existing reinforced concrete beams to form the strengthened specimens. The failure mode, deformation, crack development, cracking load and ultimate load of the beams were studied under four-point bending tests and compared with those of contrast beam. The results indicate that the load-bearing capacity and initial section stiffness of the beams can be increased effectively by using the strengthening method. Introducing UHTCC material into strengthening not only enables the composite beams to sustain the loading at a large deflection level without failure, but also disperses the cracks in upper concrete into multiple fine cracks to delay the appearance of harmful cracks on the bending face. In addition, different lengths and thicknesses of the post-poured layer lead to different failure modes. Reinforced UHTCC can satisfy higher strength and stiffness requirements. However, end stress of the strengthened beams increases accordingly with the increase of the strengthening layer stiffness. Planting reinforcing bar is an effective method for improving the bonding of the interface between the post-poured UHTCC and the existing concrete.


Bai F.-L.,Dalian University of Technology | Bai F.-L.,Dalian Institute of Building Scientific Research and Design Stock Co. | Li H.-N.,Dalian University of Technology
Jisuan Lixue Xuebao/Chinese Journal of Computational Mechanics | Year: 2011

The spatially varying ground motions were simulated based on an empirical coherency loss function and the response spectrum defined in Chinese seismic design code. Intensive numerical calculations of the responses of the trussed arch subjected to the combined spatially varying horizontal and vertical ground motion excitations were carried out. Compared with structural responses calculated using uniform excitations, numerical results have highlighted that seismic response is amplified when considering ground motion spatial variations. Each factor of ground motion spatial variations has a significant effect on the dynamic response of the structure. The conventional seismic analysis with uniform ground motion assumption or with spatial variations considering wave passage effect only may underestimate the seismic response of long span structure. Numerical results also indicate that considering simultaneous vertical and horizontal ground motions will lead to more accurate response predictions of the trussed arch as compared with those obtained by considering horizontal excitations only.


Xu S.L.,Zhejiang University | Wang N.,Dalian Institute of Building Scientific Research and Design Stock Co. | Zhang X.F.,Dalian University of Technology
Materials and Structures/Materiaux et Constructions | Year: 2012

Ultra high toughness cementitious composites (UHTCC), which has metal-like deformation and crack width restricting ability, is expected to be utilized as retrofit materials. For this application, much attention needs to be paid to the working performance of structure members composed of UHTCC and existing concrete. This paper presents an investigation on the flexural behavior of plain concrete beams strengthened with UHTCC layer in tension face. The effect of UHTCC layer thicknesses on first crack load, ultimate flexural load, crack width, and load-deflection relationship is examined. The experimental results indicate that the use of UHTCC layer significantly increases the first crack load and ultimate flexural load. The first crack load and ultimate flexural load of composites beams increased with the increase of the UHTCC layer thickness. Considerable reduction in crack width was observed for composite specimens, as UHTCC layer restricted the cracks in upper concrete and dispersed them into multiple fine cracks effectively. Moreover, in comparison to plain concrete beam, composite beams could sustain the loading at a larger deflection without failure. Based on the plane section assumption, etc., a calculation method to predict the flexural capacity of composite beam was proposed. Good agreement between predictions and experiments had been obtained. © RILEM 2011.


Bai F.-L.,Dalian University of Technology | Bai F.-L.,Dalian Institute of Building Scientific Research and Design Stock Company Ltd | Li H.-N.,Dalian University of Technology
Gongcheng Lixue/Engineering Mechanics | Year: 2011

Ground motion spatial variation effects on seismic response of an actual long span trussed arch structure are investigated. Intensive numerical simulations of the responses of the trussed arch subjected to ground motion excitations are carried out. The ground motion spatial variations associated with wave passage effect, coherency loss effect and different local site effect are considered. The effects of non-uniform ground motion wave apparent velocity, coherency loss and local site conditions on structural responses are discussed. In numerical calculations, the simulated spatially varying ground motions are individually compatible with the response spectrum defined in Chinese Seismic Design Code, and are compatible with an empirical coherency loss function between each other. Numerical results indicate that each factor of ground motion spatial variations has a significant effect on the dynamic response of the structure, and neglecting ground motion spatial variations in analysis may lead to the underestimation of structural responses. To obtain an accurate structural response assessment and a better design of long span trussed arch structure, a reliable ground motion spatial variation model is essential. The results obtained could provide useful reference for practical design of trussed arch structures.

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