From a mesoscopic view, recycled concrete (RC) can be taken as a multi-phase composition which is consisted of aggregate, mortar and the interface between them. The three-dimensional grading curve of aggregate is determined by referring to the Fuller curve. And with the Monte Carlo method, the meso-sample of RC can be developed randomly. By the gradually mesh generation method, the randomly distributed aggregates, interfaces and mortar are meshed in turn. Finally, with the meso finite element model just generated, when the recycled aggregate (RA) mixing proportion is 0%,40%,70% and 100%，the numerical uniaxial compression fracture experiments of the RC specimen are carried out respectively. And the damage distribution and evolution processes are simulated and tracked. As the simulation results demonstrate, the damage appearance of cylinder specimen belongs to oblique section damage which gradually grows with the increment of displacement. Meanwhile, the damage region spreads to both sides of the oblique section which corresponds to the CT scanning pictures. Observed from the stress-strain diagram of numerical simulation and servo test, as the RA content increases, the peak strength decreases and so does the slope, which means the compression elastic modulus becomes smaller and agrees with the fact that the mixture of RA leads to the softening of inner structure.  

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On the basis of the test results of nine steel-fiber high-strength concrete corbel specimens subjected to a vertical load, the influence of the steel fiber content on the shear performance of corbels was analyzed. The softened strut-and-tie model (SSTM) was used to analyze the shear strength of steel-fiber high-strength concrete corbels, taking into consideration the shear contribution of steel fibers. A calculation model for the shear strength of steel-fiber high-strength concrete corbels is proposed, and a database for 26 steel-fiber high-strength concrete corbels was created by using the model. The results obtained according to the codes ACI318-19, EC2, CSA A23.3-19 and the softened strut-and-tie model were compared with the experimental values to verify the rationality of the model. The findings showed that steel fiber can effectively limit the crack width and improve the crack morphology. The overall average value of the ratio between the experimental and the predicted strengths of the model was 1.082, and the variance was 0.004. The values predicted with the proposed calculation model were closer to the experimental values than those calculated according to the codes. This study provides a definite mechanical model that can reveal the shear mechanism of steel-fiber high-strength concrete. It can reasonably predict the shear strength of steel-fiber high-strength concrete corbels.

A planar construction drawing is usually used to guide the construction of reinforced concrete structures in the construction industry. Due to a lack of effective technical methods, the accuracy of rebar engineering lofting is insufficient. The rejection rate of rebar is high, which results in high processing costs. Under the background of intelligent construction and BIM technology, the prefabricated factory adopts an automatic production mode to concentrate on steel bar processing, which improves production quality and processing efficiency and reduces production costs. Based on Revit secondary development, using the C# programming language, combined with the Revit API development interface, an automatic 3D modeling plugin for a reinforced concrete variable cross-section column is developed. The BIM model of steel bars is quickly generated, and the engineering quantity of steel bars is automatically calculated, which saves time for the designer to build the BIM model. It is conducive to the automatic assembly and intelligent construction of reinforced concrete engineering, which promotes the information and intelligent development of reinforced concrete structure construction.