Reconstruction of concrete numerical model based ondamage zoning theory and CT number(PDF)
长安大学学报（自然科学版）[ISSN:1006-6977/CN:61-1281/TN]
- Issue:
- 2020年2期
- Page:
- 66-73
- Research Field:
- 桥梁与隧道工程
- Publishing date:
Info
- Title:
- Reconstruction of concrete numerical model based ondamage zoning theory and CT number
- Author(s):
- FANG Jianyin; LI Na; DANG Faning; PAN You; REN Jie
- （School of Civil Engineering and Architecture， Xian University of Technology, Xian 710048， Shaanxi， China）
- Keywords:
- bridge engineering; concrete; CT test; model reconstruction; damage crack
- PACS:
- -
- DOI:
- -
- Abstract:
- In order to establish a numerical model which truly reflect the internal mesoscopic structure of concrete specimen, and study the damage evolution characteristics of mass concrete, the uniaxial compression CT scanning test of concrete was carried out based on portable power load equipment combined with medical Marconi M8000 spiral CT. CT images of concrete samples under uniaxial compression were obtained. Based on the damage partition theory, a probability statistics method to determine the threshold was proposed, and the CT scan images of concrete were divided into aggregate area, hardened cement area and crack area. Based on the coordinates of each resolution unit in the CT scan, a structural random numerical concrete model was established, and the damage evolution characteristics of concrete under uniaxial static compression and tension were studied. The results show that the mesoscopic structure of structural random numerical concrete model is very close to the mesoscopic structure of concrete samples, and the interface thickness between aggregate and mortar in this model is only about 0.04 mm, which is very close to the interface thickness of real concrete samples (10 to 50 μm). In the condition of uniaxial tension and compressive stress, concrete microscopic cracks start to initiate at the initial defect with relatively weak strength, with the increase of stress, cracks expand and connect around the interface with relatively weak strength of aggregate, and the strength of the interface largely determines the strength of concrete. In the condition of uniaxial compressive stress, there are more cracks in the concrete samples and most of them are shear cracks. In the condition of uniaxial tensile stress, there are more crack initiation points in the samples at the beginning, and several cracks developed simultaneously, and however, with the increase of the stress level, only one major crack nearly perpendicular to the loading direction is finally generated in the sample. Under uniaxial compression or uniaxial tensile stress, due to the slow loading speed, the crack growth in the sample does not pass through the aggregate. 2 tabs, 9 figs, 22 refs.
Last Update: 2020-04-09