STUDY ON SEISMIC BEHAVIOR OF RECYCLED CONCRETE FRAME CONSTRUCTION

Transcription

1 STUDY ON SEISMIC BEHAVIOR OF RECYCLED CONCRETE FRAME CONSTRUCTION Zhenglong CUI (1), Masahumi KITATSUJI (2), and Reiji TANAKA (3) (1) College of Civil and Architectural Engineering, Liao ning Technical University, Fu xin ,China (2) Miyagi University, Sendai, , Japan, (3) Faculty of Engineering,Tohoku Institute of Technology, Sendai, , Japan Abstract: 5.12 Wenchuan Earthquake not only induced large casualty, but also produced large solid waste. How to deal and use solid waste had been a problem which had the focus of researchers in China and abroad. It s an effective method to develop green concrete, which can reduce city environment burden for cycling waste concrete. It is necessary to further know different mechanical properties of recycled aggregate concrete in order to test its practical application on building structures, especially on reinforced concrete. Mechanical properties is the main focus in this paper, to research destructive form, load capability, and energy absorption capability of recycled reinforcement concrete frame construction compared with normal reinforced concrete frame construction under the horizontal low cycle repetition load test. It concluded that recycled reinforced concrete frame construction showed good seismic behavior while the destructive form, load capability, and energy absorption capability decreased compared with normal reinforced concrete column under the same class grade. It is possible to use recycled aggregate concrete in structure members, and the mechanical properties do satisfy this. Keywords : recycled aggregate concrete; reinforced concrete;frame construction; history loop; seismic behavior 1. INTRODUCTION The paper focused on the mechanical properties of recycled aggregate concrete[1]. The axial load ratio of the frame construction column was FRN was shortened for recycled aggregate concrete with 100% recycled aggregate replacement natural aggregates. The horizontal low cycle repetition load test was carried out on recycled reinforced concrete framework structure model. The model was one-third of practical structure. The destructive form, load capability, and energy absorption capability were investigated, and it discussed practical application possibility of recycled aggregate on building structure from seismic behavior. The experiment used natural reinforced concrete as a reference to test its mechanical properties and also carry the bending shear test. 2. EXPERIMENT 455

2 2.1 Specimen design Table 1 was shown the type of experimental specimen, and there were two groups, one was recycled reinforced concrete, and the other was natural reinforced concrete. Table 1: Type of specimen Type of concrete Specimen name Using materials Experiment strength of concrete/mpa axis compression ratio Recycled aggregate concrete FRN Recycload coarse aggregate Normal fine aggregate Normal concrete FNN Normal coarse aggregate Normal fine aggregate Specimen s dimension and distributed steel Fig.1 shows the shape, dimension and reinforcement of the models which were kept the same. The sectional dimension of beam were that the length of experimental zone was L=1250mm, shear span ratio was 2.5, beam depth was D=250mm, and beam breadth was B=250mm. Stressing reinforcement was D10 and hoop reinforcement was D6@ D10 D10 2-D6@50 4-D10 2-D6@50 4-D10 2-D6@50 D Fig.1: Shape and dimension of specimen 2.3 Materials (1) Recycled coarse aggregate Recycled coarse aggregate used pouring normal concrete (compression strength: 36.3 MPa) as base concrete, which was cured at 28d sprinkling and watering in the air, was broken down using minor type slump and shaved by 5mm shaking sieve. After washing and drying, the aggregates whose dimension is bigger than 5 mm were used as coarse aggregates. Drawing-off materials allotted from recycled aggregate and fine aggregate, according to JIS material experiment [2] was used to measure the basic physical properties and surface dryness 456

3 density, hygroscopic coefficient, unit capacity, and fineness modulus of coarse and fine aggregates. Table 2 is basic material properties of coarse aggregate, fine aggregate and comparing normal aggregate. Measurement item Density Table.2: Basic characteristics of applied aggregates Recycload Coarse Aggregate Normal Coarse Aggregate Normal Fine Aggregate / g.cm ー Absorption / % Unit weight / kg.l ー Fineness modulus (2) Recycled concrete The experiment used 100% recycled coarse aggregate and normal mountain sand as fine aggregate, instead of normal macadam. Because the mix proportion of recycled concrete (RCA) is not definitely defined, the experiment were finally defined by the mix proportion based on concrete s workability after spilling many times. Table 3 was shows a comparison of the mix proportions between recycled aggregate concrete and natural concrete (NN), and table 4 was shows the mechanical properties. Table 3: Mix proportion of concrete Type of Slump Air Unit Amount /Kg.m -3 W/C S/a Concrete /mm /% Water Cment Fine Aggregate Coarse Aggregate AE RN NN Table 4 Mixture composition of the mechanicals type of W/C Compressive Modulus of Strain /% concrete /% strength Elsticity /Gpa RN NN (3) steel bar Table 5 shows the properties of steel bars used in the experiment. The experiment choused main reinforcement of recycled reinforced concrete and normal reinforced concrete whose diameter is D13(SD345). The steel bar s tensile experiment shows that, main reinforcement D13 and shearing reinforcement D10 have a definite yield point. 2.4 Loading and the method of measuring displacement Figure 2 shows the loading device and the method of measuring displacement. The whole specimen s loading is the proximity which uses the horizontal low cycle repetition load test that 457

4 keep the column tap s axis force fixed during the process of the experiment. The jacking apparatus apply axis forces and using oil pressure jacking apparatus to apply horizontal low cycle repetition Table 5: Mechanical properties of steel bars type of steel Main Reinforcement Shearing Reinforcement Steel diameter / mm Yield strength /Mpa Yield strength Tensile strength Modulus of Strain/ % / MPa Elasticity/ GPa load. The load application method is controlling displacement whereby loading applied in multiples of displacement, that is, the process of applying load is ±0.5,±1.0,±1.5, ±2.0. Each level of displacement should have cyclic load once, this should continue for each level until the load capability of structure fall to 85% of the maximum load, then stop the experiment. The experiment layout 14 main reinforcements strain measuring points and 7 shearing reinforcements strain measuring points in the column experiment plot. The column up-bottom ends have 2 displacement meters laid out, which measure strain and relative horizontal displacement between the main reinforcement and shearing reinforcement. ロードセル (1000kN) 試験体 オイルジャッキ (1000kN) P L - 9 P L - 9 テスティングフロアー Fig. 2: Loading equipment and displacement measuring method 3. RESULTS AND DISCUSSIONS 3.1 The damaging process Fig. 3 shows the final crack situation. Destructive form between recycled reinforced frame structure and natural reinforced frame structure were nearly the same under the same axial load ratio, whose column damage prior to beam. 3.2 P- Curve[3] Fig. 4 shows the P- hysteresis loop of the models. It demonstrated that hysteresis loop of the models were nearly the same, load capability decreased slowly after the max load, 458

5 structure emerged strength and stiffness degradation in different levels, and showed obvious bending failure. F RN F NN Fig. 3: Last crack situation of a frames P(kN) 70 FRN P(kN) 70 FNN R(1/100rad) R(1/100rad) Fig. 4: P- 4. CONCLUSIONS curve The study researched on the recycled reinforced framework seismic behavior with 100% recycled aggregate replacement of natural aggregates. Comparing natural reinforced framework on mechanical properties, drew the following conclusions: (1) The damage process and P- curve property of recycled reinforced concrete frame was similar to normal reinforced concrete under the same strength class. (2) The seismic behavior between recycled reinforced concrete frame and normal reinforced concrete was reduced. Recycled reinforced frame had a good energy absorption capability and deforming capability under low axis-pressure ratio of the frame, which empress that it is feasibility to use on frame component in designs with higher seismic behavior demands. 459

6 REFERENCE [1] (Foundation) Japan Concrete Institute Recycling Study Group report to the concrete material of waste tokyo:(ltd)hokou publication, Heisei 15 year [2] Japanese Standards Association Construction relations JIS Survey(Test method etc.),tokyo: Japanese Standards Association publishing company,heisei 12 year [3] Sun Yuedong,Xiao Jianzhung,Zhou Deyuan. An experimental study on the seismic behavior of recycled concrete frames. China civil engineering journal,2006, 39 (5):