On the determination of concrete armour unit stresses including specific results related to Dolosse

Numerical simulation of breakages of concrete armour units using a three-dimensional fracture model in the context of the combined finite-discrete element method

“…One key aspect to be addressed before numerical modelling can be applied in design work is to define and find a means of applying the wave loading conditions that units are exposed to. According to previous research, there are five main types of loads acting on armour units (Burcharth, 1981a;Howell, 1988;Burcharth et al, 1991), which are listed in Table 1. The complexity of the in situ loading conditions make it very difficult even impossible to accurately represent reality in physical experiments and numerical simulations.…”

New modelling and analysis methods for concrete armour unit systems using FEMDEM

“…Such distributions are considered likely to also yield log-normal distributions of maximum stress components, (tensile and differential) as were observed for double-layer slender model units investigated by Burcharth et al (1991). For the looser packs, the simulated maximum contact force per unit was observed to vary 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 24 between 0.5 to 3 times W. For the densest pack, maximum contact forces of between 4 or 5 times W were noted (with a few higher maximum contact forces also observed).…”

“…using instrumented units within disturbed packs, and carefully examined strength scaling laws to rescale dynamic and static results. Burcharth et al (1991Burcharth et al ( , 2000 measured the stresses inside six model units under a suite of ramp tests and wave structure conditions for randomly placed slender units (Tetrapods and Dolosse). The new design formula obtained was a shift from the previous ones geared only for hydraulic stability.…”

Prototype Drop Tests of Cube and Cubipod Armor Units

“…According to Burcharth et al (1991), as a rule of thumb, concrete stresses in CAUs due to non-impact loads increase linearly with the unit size, while impact-induced stresses increase with the square root of the unit size. Taking into consideration the increase in concrete stress according to the unit size, and the higher mechanical strength of massive CAUs, 16-tonne (7.1 m 3 ) Cubipod prototypes were considered for the prototype drop tests because they are larger than any drop tested bulky CAU reported in the literature and the armor unit weight is adequate for large breakwaters along the Spanish Mediterranean coast, corresponding to 1/50…”

“…In a parallel study, Nishigori et al (1989) experimentally analyzed the similarity laws of impact for Tetrapod CAUs. Burcharth et al (1991) Small-scale drop tests and numerical models are not very reliable when assessing CAU structural strength in prototype conditions; therefore, several prototype scale dynamic tests have been used over the past three decades to assess the structural strength of CAUs. Burcharth (1981) and Silva (1983) tested 1.5-tonne and 5.4-tonne Dolosse, and 1-tonne to 27-tonne cubic blocks, respectively.…”