Compressive behavior of stirrup-confined concrete columns: size effect and a size-dependent stress-strain model

Numerous studies have indicated the existence of size effect on axial compression behavior of stirrup-confined concrete columns. However, most of these studies have been stressed in terms of nominal compressive strength. The investigation on the size effect of axial strain (at peak load) and descending branch was limited. In this study, the size effect behavior of square stirrup-confined concrete columns under axial compression was explored, by using 3-D mesoscale simulation method. Based on the numerical and available experimental results, the influence of specimen size on the peak axial stress (i.e., the compressive strength), the corresponding strain and the softening rate were explored. Moreover, the quantitative relationships between specimen size and the peak axial stress, the corresponding strain and the softening rate for circular and square stirrup-confined concrete columns were derived. Finally, considering the size effect of peak axial stress, the corresponding strain and the softening rate, a novel stress-strain model describing the axial compression behavior of stirrup-confined concrete was developed. The proposed model was verified by comparing with the available experimental results and the existing models provided.

Preliminary Study on Different Materials of Geogrid by using Finite Element Model

In recent years, environmental concerns related to the overexploitation of natural resources and the need to manage large amounts of wastes arising from construction activities have intensified. This paper presents a preliminary study carried out to characterize the interaction impact with different material geogrids (a polyester (PET), high-density polyethylene (HDPE), and polyurethane (PU) geogrid through Finite Element Model (FEM) simulation. The effects of the geogrid specimen size, displacement rate by the pressure through the geogrids are evaluated. The results show that the measured peak pullout resistance of the geogrid increases with the specimen size imposed displacement rate The pressure ranged from 10 000 N/m2 and 50 000 N/m2. The FEM analysis result is important due to quantify the benefit-cost ratio of geosynthetics application in pavements needed for a detailed Life-Cycle Cost Analysis (LCCA).

Mathematical modelling of crushed rock dust concrete: Performance using compressive strength

The paper gives out a mathematical model developed using linear regression statistical method to envisage the 28-day strength of CRD concrete, considering M20, M30 and M40 grades concrete and CRD replacement percentages of 0%, 10%, 20%, 30% and 40% by weight of cement. Strength results of M40, M30 and M20 grades concrete are used to develop the relationship between CRD content and compressive strength. The ratios of compressive strengths between CRD and control concrete (CC) have been related to CRD replacement percentage. The expression, derived is with strength ratios and not with experimental strength values. The mathematical equation developed is independent of the specimen parameters and may be applicable to all types of specimens. The model is considered as it involves non-dimensional variables and is independent of the specimen size, water to binder ratio (w/b) and grade of concrete.