Jinqing Jia

Different from the traditional concrete mixing procedure, the innovative post-filling coarse aggregate concrete (PFCC) reduces the cost of pumping concrete by increasing the coarse aggregate content and reducing the usage of cement. Previous studies have shown that PFCC enhances the compressive strength, elastic modulus, and flexural strength of concrete. In this paper, the shear behavior of 13 post-filling coarse aggregate concrete beams and 3 control beams was tested to determine the relationships between the shear performance of the beam and the post-filling coarse aggregate ratio, concrete strength grade, shear span ratio and stirrup reinforcement ratio. The results showed that the ultimate shear capacity of beam specimen increases first and then decreases with the increase in post-filling coarse aggregate ratio, reaching the maximum at 15% post-filling ratio. The results also indicated that the ultimate shear capacity of the beam increases with the increase in concrete strength grade and stirrup ratio. However, experimental results exhibited that the ultimate shear capacity decreases as the shear span ratio increases. This study provides a reference for the application of post-filling coarse aggregate concrete in engineering practice.

The increase of coarse aggregate content decreases the shrinkage of concrete, decreases the cost of concrete production as well as reduces the carbon dioxide emission to the environment. In this study, the mixture proportions of PFCC (post‐filling coarse aggregate concrete) for C40, C50, and C60 were designed and the comprehensive performances of workability, compressive strength and elastic modulus were conducted experimentally. Then, 15 reinforced concrete columns made by PFCC with different concrete grades and post filling rates (PFR) were designed and tested. The failure mode, load‐deflection curve, load‐strain curve and load bearing capacity were analyzed and elaborated. Results showed that, compared with the conventional concrete, the compressive strength and elastic modulus of the post filling coarse aggregate concrete were improved, which reached the highest when the post filling rate is 20%. At the same time, the load bearing capacity of column specimen increased first and then decreased as the post filling rate increased, with the transition point being at 10% post filling rate. This study provides reference and research data for technical regulations and design specifications of structural members made of post filling coarse aggregate concrete.

An optimized sensor placement strategy will be extremely beneficial to ensure the safety and cost reduction considerations of structural health monitoring (SHM) systems. The sensors must be placed such that important dynamic information is obtained and the number of sensors is minimized. The practice is to select individual sensor directions by several 1D sensor methods and the triaxial sensors are placed in these directions for monitoring. However, this may lead to non-optimal placement of many triaxial sensors. In this paper, a new method, called FRPACS, is proposed based on the ant colony system (ACS) to solve the optimal placement of triaxial sensors. The triaxial sensors are placed as single units in an optimal fashion. And then the new method is compared with other algorithms using Dalian North Bridge. The computational precision and iteration efficiency of the FRPACS has been greatly improved compared with the original ACS and EFI method.