Experiment Research On Shearing Behavior Of Concrete Short Beams With Steel Plate

Through an experimental research on shear capacity of 15 concrete short beams with steel plate under concentrated load, this paper discusses the feasibility and validity of steel plate replacing horizontal and vertical stirrups which have shear-resistance behavior, and thus gropes for a new construction method for the design of deep flexural members. Simultaneously it can simplify construction in areas of congestion and bring convenience for construction of concrete. Based on the experimental results, the following conclusions have been drawn:(1) From the application of load to the failure, the concrete short beams with steel plate experience three stages as the elasticity working stage, working with cracks and the failure stage. Three types of failure are identified with specimens. These are: diagonal compression, shear compression and diagonal tension.(2) When span depth ratio l₀/h =2～5 for concrete short beams with steel plate, strain of concrete in the mid-span basically conforms to plane cross-section assumption.(3) The arching action and the beam action coexist in short beams. The arching action weakens while the beam action strengthens gradually along with increase of span-depth ratio (or shear-span ratio). For short beams of low shear-span ratio, the strain of longitudinal reinforcement which next to the support position increases rapidly along with load increasing, it may up to the strain of longitudinal reinforcement in the mid-span while beam fails. Therefore, it need to strengthen the anchorage of longitudinal reinforcement, and to prevent anchor destruction of short beams.(4) Before diagonal crack appears, the strain of steel plate is very small. The relationship between load and strain remains linear. However, the strain of steel plate increases suddenly in intersection direction with diagonal crack when diagonal crack appears, and reaches maximum when short beam fails. In addition, steel plate has great influence on shear capacity of short beam when shear-span ratio is high.(5) The factors affecting the shear capacity of concrete short beams with steel plate such as span-depth ratio, shear-span ratio and steel thickness are discussed in detail. Under concentrated load, the shear capacity of concrete short beams with steel plate reduces with the increase of shear-span ratio, while increases along with steel thickness increasing. However, the effects of span-depth ratio to the shear capacity is so little that it can not be considered in calculating the shear capacity of concrete short beams with steel plate.(6) Formula of calculating the shear capacity of concrete short beams with steel plate are proposed as follow:Method 1:Where 1≤λ≤3 , whenλ< 1, takeλ= 1 ;whenλ>3 , takeλ=3.Method 2:Where 1≤λ≤3 , whenλ< 1, takeλ= 1; whenλ>3 , takeλ= 3.The formulas above have clear forms and short-out calculations which are not only well in accordance with the test results, but also have certain security guarantees.