مقاله انگلیسی رایگان در مورد استفاده دوباره از مصالح بتنی بازیافتی برای اجزای باربر – اسپرینگر 2017

Recycled aggregates recovered from abandoned buildings or demolished concrete structures were reused to produce concrete columns as new building components. A quasi-static test on 10 recycled aggregate concrete flled steel tubular (RACFST) columns was carried out. The mechanical properties of RACFST columns in the study include failure mode, hysteretic loops, skeleton curves, stifness deterioration curves and energy dissipation capacity. RACFST columns with diferent recycled aggregate replacement ratios were tested under constant axial load and cyclic lateral load. The seismic performance of the columns was analyzed. The experimental results indicate that concrete adding recycled aggregates does not reduce the lateral stifness of the columns, and their energy dissipation capacity is nearly as good as that of natural aggregate concrete flled steel tubular columns. The usage of recycled aggregate concrete has little infuence on the lateral load-bearing capacity and the stifness deterioration of RACFST columns. The current calculation for natural aggregate concrete flled steel tubular columns to estimate the lateral load-bearing capacity of RACFST columns tends to be relatively conservative. The reuse of recycled aggregates for load-bearing components of building structures especially for concrete flled steel tubular columns is feasible.

Introduction

The rapid development of urbanization in China results in a large amount of demolished building materials, in which concrete is the most. However, the recycled aggregates recovered from abandoned buildings or demolished concrete structures can be reused to produce recycled concrete if properly treated such as crushing, washing, sieving and grading. The aggregate made from abandoned buildings or demolished concrete structures can be used to replace some or all of the coarse aggregate in concrete mixture to form recycled aggregate concrete (RAC). Up to now, extensive researches have been carried out on the mechanical properties of RAC, including the study of recycled concrete members and structures. It was shown that RAC could be used mainly in the structures with lower stress or force level because of the characteristic limitations of recycled aggregate itself [1, 2]. However, thanks to the combination of RAC and concrete flled steel tubular (CFST) structures, which has been put forward by researchers and instantly aroused an interest in practice [3], the method of flling the steel tube with recycled aggregate concrete or demolished concrete lumps partially or wholly not only reduces the whole weight of buildings, but also decreases the price of concrete members [4]. As the recycled aggregate has a positive infuence on the ductility of RAC structures [5], it is desired to apply on the buildings with high seismic resistance requirements or the areas with frequent destructive earthquakes. Meanwhile, recycled aggregate concrete is considered to provide high and obvious economic and social benefts and promising application prospect [6]. The basic mechanism of RAC filled steel tubular (RACFST) members is similar to the situation of natural aggregate concrete flled steel tubular members, and tests for the material have shown that the Poisson’s ratio of RAC is nearly the same as that of natural aggregate concrete [7], which tends to indicate that the steel tube can be applied on confning RAC as it does for natural aggregate concrete. A series of investigations on the mechanical property, durability and structural performance of RACFST columns have been carried out in the past 15 years after initially studied in the late 90’s [8]. The related studies are ranged on the mechanical performance of RACFST columns, especially under axial or eccentric compression [9–12], the shrinkage and creep of the core concrete [13], the working mechanism of steel tube confnement [14, 15], the energy dissipation capacity of RACFST columns [16, 17], and so on.