PSI - Issue 64

Tom Molkens et al. / Procedia Structural Integrity 64 (2024) 1484–1491 Tom Molkens & Mona El-Hallak Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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the top of the beam measuring 80×80 mm and 200 mm on either side to accommodate a small linear variable differential transformer (LVDT) (measuring range 5 mm, accuracy <0.5% - due to larger slips measured during the test the devices have been reset one till two times). The local effect on the moment of inertia is limited to a 16% reduction, but under the influence of a constant moment along the entire length, the influence on the deformation it is less than 2%. In addition, the cut-out was done only at the location of a zero-moment point, so the effect on the overall force action is negligible. The total length of the beam is 3m with a 200mm overhang at each end.

Section CC

Section AA

BB

BB

Section AA

Slip measurement device (LVDT)

Section AA

Section BB

Section CC

1Ø16 or 1Ø20 ×700mm Ordinary steel bars till cutout without overlap

2Ø16 ×3000 mm

Stirrups Ø10/60

Figure 2. Schematic overview of the test setup with reinforcement details, sections, and picture of the cut-out provisions.

Using the given dimensions from Figure 2 and the properties from Table 1, a cracking moment of 10.8 kNm can be calculated. Taking into account its own weight (1.73 kN/m), cracking should occur more or less simultaneously above the support point and below the loads at a total load of approximately 95 kN. Loads were applied by two independently force-controlled jacks at a loading rate of 0.08 kN/s until intermediate stops to facilitate strain measurements. Differences between the two spans are therefore not averaged through a distribution profile. 3.4. Calculation of limit state and failure capacities Rectangular stress distribution in the concrete was used to calculate the ultimate bearing capacity at flexure (M Rd ), see (7). Where A g is the area of the bending reinforcement, f fd is the design value of this reinforcement, h is the height of the section (300 mm), c is the cover (25 mm), Ø is the diameter of the reinforcement (16 or 20 mm) and f cd is the calculated compressive strength of the concrete at bending. = (ℎ − − Ø2 − 2 ) (7) With an optimal redistribution of the bending moments according to the capacity of the sections, the maximum total external load P Rd can be calculated. Where M Rb and M Rt are the capacity of the section with tension on the bottom or top, via Eq. (7), the relationship between them can be found in Eq. (8). =( + 2 ) 8 (8) Based on the design values, ignoring the effect of dead load, the total effective loads for a top bar of Ø16 and Ø20 mm are calculated to be 536 kN and 592 kN, respectively. Without safety factors and considering only the maximum