A new construction scheme was recently developed for precast segmental concrete beams by replacing steel tendons with internal unbonded carbon-fiber-reinforced polymer tendons. The discontinuous behaviors of the opening joints and unbonded phenomenon of tendons made their flexural behaviors more complicated than those of monolithic beams and members with bonded tendons. Currently, the knowledge on the structural performance of precast segmental concrete beams with internal unbonded carbon-fiber-reinforced polymer tendons is still limited. An efficient numerical model is urgently needed for the structural analysis and performance evaluation of this new construction scheme. In this paper, a new beam–cable hybrid model was proposed accounting for the mechanical behaviors of open joints and unbonded tendons. The numerical model was implemented in the OpenSees software with the proposed modeling method for joint elements and a newly developed element class for internal unbonded tendons. The effectiveness of the proposed model was verified by comparisons against two simply supported experimental tests. Then, the numerical model was employed to evaluate the flexural performance of a full-scale bridge with a span of 37.5 m. Compared with the precast segmental concrete beam with external steel tendons, the scheme with internal unbonded carbon-fiber-reinforced polymer tendons significantly improved the flexural capacity and ductility by almost 54.6% and 8.9%, respectively. The span-to-depth ratio and prestressing reinforcement ratio were the main factors affecting the flexural behaviors. With the span-to-depth ratio increasing by 23%, the flexural capacity decreased by approximately 38.6% and the tendon stress increment decreased by approximately 15.7%. With the prestressing reinforcement ratio increasing by 65.4%, the flexural capacity increased by 88.7% and the tendon stress increment decreased by approximately 25.2%.
Interfacial slip effects and the unbonded phenomenon of external tendons are the key mechanical features of the externally prestressed steel-concrete composite beams (EPCBs). In this paper, an 8-node fiber beam element is built for the nonlinear analysis of the composite beam with interfacial slip effects. A multi-node slipping cable element is proposed for the simulation of external tendons. The derived formulations are programmed in OpenSees as newly developed element classes to be conveniently used for the flexural analysis of EPCBs. The effectiveness of the proposed model is fully verified against the experimental tests of simply supported and continuous beams and then applied to the parametric study. The results show that the increasing deviator spacing will significantly decrease the tendon effective depth at ultimate states and further decrease the flexural capacity. The larger effective depth is beneficial to the tendon stress increments and further improves the flexural capacity. The enhancement of interfacial shear connection degree will increase the structural capacity but the effects on the tendon stress increments and second-order effects were not monotonic.
Introduction: Chinese hospitals still face various barriers to implementing pharmaceutical care. The quantitative instrument for measuring these barriers in China is scarce. This study aims to develop and validate a scale for measuring barriers to providing pharmaceutical care in Chinese hospitals from the perspective of clinical pharmacists.Methods: The scale was developed based on existing literature and qualitative interviews with 20 experts. The scale was included in a small-range pilot survey and then administered to a validation survey in 31 provinces in China. Exploratory factor analysis was used to identify the structure of the scale. Confirmatory factor analysis was applied to verify the structure of the scale and to validate the scale’s convergent and discriminative validity. Known-group validity was also examined. Cronbach’s alpha examined the internal consistency reliability of the scale.Results: 292 scales were completed and returned for a response rate of 85.6% in the pilot study. Exploratory factor analysis of the scale suggested a five-factor solution (Cognition and attitude, Knowledge and skills, Objective conditions, External cooperation, and Support from managers) accounting for 66.03% of the total variance. 443 scales were sent out in the validation study, with a response rate of 81.0%. Confirmatory factor analysis demonstrated a good fit of the structural model for pharmaceutical care barriers. It showed the scale’s good convergent and discriminative validity (The average variance extracted >0.5 and composite reliability >0.7). The scale could also identify the differences in total score among the clinical pharmacists from different hospital grades (p < 0.05). Cronbach’s alpha is between 0.658 and 0.896, indicating good internal consistency.Conclusion: From the perspective of clinical pharmacists, this study has developed a scale to assess obstacles to pharmaceutical care. The scale comprehensively encompasses barriers to clinical pharmacists’ cognitive and ability-related aspects, hindrances encountered in collaborating with other health professionals and patients, and barriers to the working environment. The reliability and validity have been established through verification.
The application of CFRP tendons in precast segmental concrete beams (PSCB) as internal un-bonded prestressing reinforcement is a newly developed scheme to improve structural flexural performance. The stress increment of the un-bonded tendon, depending on the whole structural deformation, is a crucial value to be predicted for flexural capacity design. Due to the discontinuity of the opening joints, the deformation modes of segmental beams differ from the monolithic ones. The existing prediction methods built for monolithic beams can not be directly used for segmental beams. In this paper, the new prediction equations of the tendon stress increment and flexural capacity were put forward for PSCB with internal un-bonded CFRP tendons (PSCB-IUCFRP). Firstly, the differences between the deformation modes of monolithic and segmental beams were compared and clarified based on the numerical model analysis. Then, a parametric analysis was conducted on 162 numerical models, and the results were employed to evaluate the applicability of existing methods for PSCB-IUCFRP. The predictions of the ACI 318-14 model and the AASHTO LRFD model were both conservative and scattering compared with numerical results. The ACI 440.4R model underestimated the tendon stress increments of beams under one-point loading but overestimated it for those under two-point loading. According to the failure mode of PSCB-IUCFRP, a simplified curvature distribution mode was assumed, and the relation between tendon elongation and structural deflection was derived. The prediction equations for PSCB-IUCFRP were proposed using the back-calculated plastic hinge length. Compared with existing methods, the proposed equations considered the deformation characteristic of segmental beams and had clear physical significance. The predictions of the proposed method were in good agreement with the numerical and experimental results. Furthermore, a balanced prestressing reinforcement ratio equation is proposed for PSCB-IUCFRP to avoid tendon rupture-controlled failure. The proposed equations provide suggestions for the flexural design of PSCB-IUCFRP and will help to popularize this new structure.
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