Failure modes flexural

The failure mechanisms of interest in reinforced masonry wall elements include flexural, transverse shear, in-plane shear and in some cases, combined axial compression and flexure. Buckling failure modes of compression elements and connection failures are to be avoided. 

Ductility limits for structural steel members are established such that gross member collapse due to failure of the member itself or its connections is precluded. It is presumed that local and gross member instabilities are prevented by providing adequate bracing and stiffeners. Shear failure modes are also to be precluded by design. Determination of failure mechanisms and corresponding capacities for flexural members and beam-columns arc adequately covered by the LRFD specifications. 

Davidovitz, M, Mittelman. A., Roman. I. and Marom. G. (1984). Failure modes and fracture mechanisms in flexure of Kevlar-epoxy composites. J. Mater. Sci. 19, 311-294. 

Shih, G.C. and Ebert, L.J. (1986). Interface strength effects on the compressive-flexure/shear failure mode transition of composites subjected to four-point bending. J. Mater. Sci. 21, 3957-3%5. 

Flexural properties in the 0° direction are largely determined by the fiber properties however, the matrix/interphase may also control the failure mode or path which may in turn affect the strength properties of the composite. The 0° flexural properties of the composites made with bare and sized E-glass are listed in Table 7. 

As the failure mode is concerned, only the weakest Series I was broken by the shear failure of core plates but others were broken by the tensile failure of glass fibers. Therefore a certain higher flexural strength of sandwich plates is expected if the reinforcing fiber is stronger. 

Figure 4 Interlaminar shear test by short beam flexure failure modes.

The standard mechanical tests, as described in Section 7. can normally be undertaken with care for composites as a function of temperature. The difference between fiber- and matrix-dominated properties can result in different temperature dependencies. Changes in the residual thermal stresses present can occur both between the fibers and the resin, and between layers, in particular between 0" and 90 orientated unidirectional layers. Care needs to be taken in assessing the failure mode, particularly in flexural and compressive tests where there can be changes, particularly at elevated temperatures, due to the matrix providing a lower degree of support to the fibers, thus encouraging compression failure. 

Debonding failure mode 3 Debonding at flexural cracks due to high local shear stresses. 

Debonding failure modes of externally bonded flexural strengthening (EBFR). 

There are three potential flexural failure modes for FRP-reinforced concrete sections (ISIS-Canada 2003) ... 

Aram, M. R., C. Czaderski and M. MotavaUi (2008a). Debonding failure modes of flexural FRP-strengthened RC beams. Composites Part B Engineering 39(5) pp. 826-841. 

As for the tensile test, the flexural test results are in general agreement with the values predicted theoretically, except for S2 but the large difference here can be attributed essentially to its particular failure mode, which is induced by its geometry (i.e. thick upper skin and non-symmetric sandwich construction). 

Type J-BI-18 specimen has the bent in joint bar anchorage details with 18 mm diameter flexural reinforcement for beam and column. Figure 13.14 shows the load and displacement relationships for J-BI-18 specimen for both push and pull directions. Specimen J-BI-18 was designed for the beam flexural capacity of 137 KN. However, as shown in Fig. 13.14, it collapsed at 99 KN in a joint failure mode in shear. Figure 13.15 represents the formation of crack in joint during the cyclic load test. 

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