Key Laboratory of Civil Engineering Structures & Disaster Prevention and Mitigation Technology of Zhejiang Province

Hangzhou, China

Key Laboratory of Civil Engineering Structures & Disaster Prevention and Mitigation Technology of Zhejiang Province

Hangzhou, China

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Jin N.,Zhejiang University | Xu Y.,Zhejiang University | Fu C.,Zhejiang University | Fu C.,Zhejiang University of Technology | And 2 more authors.
Kuei Suan Jen Hsueh Pao/Journal of the Chinese Ceramic Society | Year: 2015

Thirty-nine small beams with ordinary concrete and fly ash (FA) and granulated blast furnace slag (GBFS) powder mixed concrete were casted. Two kinds of sustained load with 30% or 60% ultimate load were applied on the beams, and different dry-wet cycling tests, such as immersing in NaCl solution and exposing in CO2 environment, immersing in deionized water and exposing in CO2 environment and immersing in NaCl solution and exposing in atmosphere environment, were designed to analyze the deterioration process of concrete under carbonation, chloride attack and loading conditions. Test results indicated that the carbonation property of concrete mixed with FA and GBFS isworse than the ordinary concrete, because many Ca(OH)2 were consumed in the second hydration reaction. With the increasing of carbonation age, pores of concrete will be filled by CaCO3, hence the carbonation process slow down. In dry-wet cycling process, the convection zone will be stable at 7-9 mm. More chloride ions will accumulate at the concrete surface due to carbonation. In drying process, carbonation process will be suppressed by chloride salt crystal existed in concrete pores. Effect of carbonation on chloride transport is mainly embodied in two aspects: the transport of chloride will be suppressed by carbonation, but many of binding chloride will be released as free chloride. When the applied load increased from 30% ultimate load to 60% ultimate load, the ingress depth of chloride and carbonation increased seriously. Load effect on chloride transport and carbonation will be more obvious with the dry-wet cycling process. © 2015, Chinese Ceramic Society. All right reserved.


Jiang C.,Zhejiang University of Technology | Yang Y.,Zhejiang University of Technology | Yang Y.,Key Laboratory of Civil Engineering Structures & Disaster Prevention and Mitigation Technology of Zhejiang Province | Ma C.,Zhejiang University of Technology | And 2 more authors.
Kuei Suan Jen Hsueh Pao/Journal of the Chinese Ceramic Society | Year: 2015

The weighted values of anti-cracking performance parameters obtained from temperature-stress test for concrete were calculated via an analytic hierarchy process. The comprehensive index of anti-cracking performance evaluation was determined by a weighted-sum method. The results show that the weighted values of temperature corresponding to peak tensile stress, peak tensile stress, stress reserve, peak compressive stress and average rate of tensile stress are 0.362, 0.267, 0.232, 0.083 and 0.056, respectively. A higher value of the comprehensive index generally gives a better anti-cracking performance. The evaluation of anti-cracking behavior based on the comprehensive index is more rational than that based only on a single parameter. A verification example indicated that the proposed method could be reasonable and practical. ©, 2015, Chinese Ceramic Society. All right reserved.


Jiang C.,Zhejiang University of Technology | Yang Y.,Zhejiang University of Technology | Yang Y.,Key Laboratory of Civil Engineering Structures & Disaster Prevention and Mitigation Technology of Zhejiang Province
Kuei Suan Jen Hsueh Pao/Journal of the Chinese Ceramic Society | Year: 2015

A quadratic polynomial model that describes the relationship between autogenous shrinkage and compressive strength of concrete was proposed. The proposed model was based on the critical analysis that correlates autogenous shrinkage and compressive strength to capillary pores in concrete. The constants in the model were obtained via regression analysis on the experimental data reported in the previous work. Several factors that possibly affect the model such as water-binder ratio, mineral and chemical admixtures, and curing temperature were also discussed. The proposed autogenous shrinkage-strength model can be applied to concrete mixes with the total aggregate contents of 1 500-1 841 kg/m3 and sand ratios of 36.8%-45.3%. © 2015, Chinese Ceramic Society. All right reserved.


Zhao B.,Key Laboratory of Civil Engineering Structures & Disaster Prevention and Mitigation Technology of Zhejiang Province | Zhao B.,Zhejiang University of Technology | Chen X.,Zhejiang University of Technology | Shi X.,Zhejiang University of Technology | And 2 more authors.
Xi'an Jianzhu Keji Daxue Xuebao/Journal of Xi'an University of Architecture and Technology | Year: 2015

By analyzing the local deformation behavior of joint finite element model subjected in-plane bending, and using the methods about improved a yield line model (which used for calculating RHS-joint axial strength) to establish a axial rigidity calculation model for T-type RHS, a rigidity model named six-beams model is developed for unstiffened x-type RHS joints subjected to in-plane bending. The spans and section breadth of every beam (which form six-beams model) is determined by principle of minimum potential energy, and a theoretical formula for flexural rigidity is established after the boundary conditions of the beams is determined. The influence on flexural rigidity from every parameter of the joint is researched by one-parameter analysis from the datum calculated by plate-shell finite element model of RHS x-type joint. On those basis, the theoretical formula is modified. Then, a parametric formulae for predicting initial flexural rigidity of unstiffened x-type RHS joints subjected to in-plane bending is established through multi-variable nonlinear regression analyses, and the parametric formulae is reliable by comparing with results of FEA. ©, 2015, Science Press. All right reserved.


Fu C.,Zhejiang University | Fu C.,Zhejiang University of Technology | Fu C.,Key Laboratory of Civil Engineering Structures & Disaster Prevention and Mitigation Technology of Zhejiang Province | Tu Y.,Zhejiang University of Technology | And 2 more authors.
Kuei Suan Jen Hsueh Pao/Journal of the Chinese Ceramic Society | Year: 2015

Concrete structures are subjected to loading and environmental effect during the service lifetime. Based on ocean environment and deicing salt environment, recent studies on the influence of load on chloride transportation were summarized from the viewpoint of material and multi-scale. The mechanism and test methods involve the influence of concrete damage and cracks on chloride transportation in concrete. The process of uniaxial load, bending load and loading crack on the chloride transportation was discussed. The existing problems were discussed, and the further research aspects were proposed. ©, 2015, Chinese Ceramic Society. All right reserved.


Fu C.,Zhejiang University of Technology | Fu C.,Key Laboratory of Civil Engineering Structures & Disaster Prevention and Mitigation Technology of Zhejiang Province | Tu Y.,Zhejiang University of Technology | Jin X.,Zhejiang University | And 2 more authors.
Shuili Xuebao/Journal of Hydraulic Engineering | Year: 2016

Chloride transport process and service life of concrete structures are affected by surrounding environment and loading conditions. Sustained bending load of 28%, 22%, 16% and 10% of ultimate bending load was applied on 8 reinforced concrete beams by a spring loading system, respectively. Meanwhile, the local strains on the mid-span height of RC beams were measured. Immersion tests were conducted on 4 beams while drying-wetting tests were on the other 4 beams in an artificial climate chamber under the condition of chloride solution of 5%, environment temperature of 50℃ and RH of 60%. An automatic drying-wetting device was used to simulate the ocean tide. After 60 days, to determine the chloride ions concentration, the concrete specimens were drilled at tension zone and compression zone in the mid-span of the RC beam. Compared with the chloride transport process in unstressed concrete, chloride transport process was accelerated by tensile stress and suppressed by compression stress. The chloride diffusivity in concrete with tension strain of 526με is about 2.4 times faster than that in unstressed concrete, and the chloride diffusivity of concrete with compression strain of 90με is the same as the unstressed concrete, but the chloride diffusivity of concrete with the compression strain of 175με is 0.4 times slower than the unstressed concrete. And the chloride transport in RC beams under drying-wetting condition is faster than the ones under immersion condition. Among the different loading and environmental condition couplings, tension stress and drying-wetting coupling is the most serious condition for chloride transport. It can be found that the local strain of concrete is in good correlation with chloride ion diffusion coefficient, which can reflect the effect of loading on chloride transport. Within a range of strain in concrete, chloride diffusion coefficient increases with the increasing ensile strain, and decreases with the increasing compressive strain. © 2016, China Water Power Press. All right reserved.


Yuan W.-B.,Zhejiang University of Technology | Yuan W.-B.,Key Laboratory of Civil Engineering Structures & Disaster Prevention and Mitigation Technology of Zhejiang Province | Yu N.-T.,Zhejiang University of Technology | Bao Z.-S.,Zhejiang University of Technology | Wu L.-P.,Hangzhou polytechnic
International Journal of Steel Structures | Year: 2016

This paper presents an analytical solution for determining the deflection of castellated/cellular beams with hexagonal/circular web openings, subjected to a uniformly distributed transverse load. The solution is derived using the principle of minimum potential energy. To validate the derived analytical solution, three-dimensional linear finite element analysis is performed using four-node shell elements built-in ANSYS software. Good agreement between the finite element result and the present analytical solution is demonstrated. © 2016, Korean Society of Steel Construction and Springer-Verlag Berlin Heidelberg.

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