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A polymeric hybrid composite system made of high-performance concrete (HPC) and an innovative carbon/epoxy reinforced polymer (CFRP) unidirectional laminates was proposed as a retrofit system to enhance flexural strength and ductility of reinforced concrete (RC) slabs. The effectiveness of the proposed system was confirmed through experimental evaluation of three full-scale one-way slabs having two continuous spans. In this study, the results of the loading tests for the hybrid high-performance retrofit system are presented and discussed. Design limits to derive a flexural failure of a continuous RC slab strengthened with the hybrid retrofit system are extracted. Using the proposed design limits, the procedure of a flexural failure design for a continuous RC slab strengthened with the hybrid retrofit system is demonstrated with numerical examples for two types of the retrofit systems with respect to overlay strength. The flexural failure design limits can be extended for flexural and shear strengthening design with externally bonded FRP to ensure flexure failure for a continuous flexural members. © 2013 Elsevier Ltd.

In this study, one or the nonstatistical stochastic methods, i.e., the weighted integral method, is extended to analyze the semi-infinite domain. In the semi-infinite domain the region of uncertainties is vast when compared with that of the ordinary finite domain. Accordingly, the response variability in this domain has more significance than that in the ordinary finite domain. In modeling the semi-infinite domain, the coupled use of the infinite element is adopted. The results obtained using the proposed weighted integral method is compared with those obtained by Monte Carlo simulation. It is shown that the results of proposed method and those by the Monte Carlo simulation are in good agreement with each other showing the adequacy of the proposed method. In addition, the improvement in the response statistics, when the infinite domain is included in the model, is also attained, which shows the importance of the inclusion of far field in the analysis. CE Database subject headings: Stochastic models: Uncertainty analysis: Nonlinear analysis; Shell structures: Concrete, reinforced.

In this paper, the response variability of a reinforced concrete cooling tower shell due to shape imperfections is investigated, based on statistical stochastic analysis. In general, shape imperfections are modeled as ideal shapes, such as axisymmetric cosine shape and/or cyclic shape imperfections. However, these kinds of idealized imperfections cannot well enough represent the real shape imperfections in actual cooling tower shells. In this study, the shape imperfection of the cooling tower is assumed to be globally distributed stochastic fields rather than localized ones. The two geometrical parameters, i.e., thickness and radius, of a cooling tower shell are chosen as the spatially varying stochastic fields with predetermined statistical terms. The amount of additional responses revealed that the coefficients of variation (COVs) of stresses are larger than those of displacements, and that the additional response due to randomness in the cooling tower radius is larger than that in the shell thickness. The COVs of these two parameters show quite opposite trends. As the type of stochastic field approaches white noise, the response variability is decreased in the case of randomness in thickness, but increased in the case of radius.