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"Characterization of hoisting operations on the dynamic response of the lifting boom of a ship unloader" presented at IALCCE2018 by Giulia Milana

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In the current paper, the impact of the hoisting operations, on the dynamic response of the lifting boom of a ship unloader, are taken into consideration. The lifting boom is used to carry out transient dynamic analysis, since it was recognized to be the single most representative element for studying the dynamic response of these structures. The response of the lifting boom was the result of dynamic analysis comprising two components: the structure (representing the waterside portion of the boom), and the applied load (expressed as different hoisting force profiles). A comparison between the different force profiles was carried out, in order to identify the parameters that mostly influence the dynamic behavior of the structure during a loading cycle. Furthermore, a baseline case based on pseudo-static analysis (as standard recommendation FEM 1987) was introduced and comparisons carried out in terms of vertical displacement and bending moments.

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"Characterization of hoisting operations on the dynamic response of the lifting boom of a ship unloader" presented at IALCCE2018 by Giulia Milana

  1. 1. Reducing Uncertainty in Structural Safety Special Session SS6 Ghent, Belgium 28-31 October 2018
  2. 2. Giulia Milana, Kian Banisoleiman and Arturo González Characterization of Hoisting Operations on the Dynamic Response of the Lifting Boom of a Ship Unloader
  3. 3. The Structure UPPER SUBSTRUCTURE LOWER SUBSTRUCTURE WATERSIDE TIES REAR TIES LIFTING BOOM REAR BOOM WATERSIDE PORTAL LANDSIDE PORTAL
  4. 4. Unloading Cycle TRAVELLING EMPTY GRAB HOISTING OPERATIONS TRAVELLING FULL GRAB Lowering empty grab Lifting full grab
  5. 5. Hoisting a grounded load • F.E.M. 1.001 3rd edition 1987, Rules for the Design of Hoisting Appliances • BS EN 1991-3:2006, Part 3: Actions induced by cranes and machinery • BS EN 13001-2:2004+A3:2009, Crane safety-General design 𝜙2 = 𝜙2,𝑚𝑖𝑛 + 𝛽2 ∙ 𝑣ℎ Hoisting speed f(crane) Dynamic Factor
  6. 6. Equivalent Model Lifting Boom ky kx Waterside Outer Tie Waterside Inner Tie kOT kIT Lifting Boom k1 k2 M1 M2 L1 A, I, r EQUIVALENT MODEL FOR LIFTING BOOM (Adapted from Zrnic et al. 2006) MODE SHAPES NATURAL FREQUENCIES Natural Frequenci es Current model (Hz) Zrnic model (Hz) Error (%) I 1.45 1.46 0.7 II 3.21 3.22 0.3 III 8.43 8.48 0.6 L
  7. 7. HoistingAssumptions • Two sprung masses model adopted for the trolley+grab+payload system • Moving system fixed at location 𝑥 𝑇 during hoisting operations • Initial condition = Final condition travelling phase 𝐹 𝑡 = 𝐹 𝑇 + 𝐹𝑃 𝑡 𝐹 𝑇 = 𝑚 𝑇 ∙ 𝑔 Force component due to trolley mass fixed at location 𝑥 𝑇 𝐹𝑃 𝑡 = 𝑚 𝑃 ∙ 𝑎∗ (𝑡) Force component due to payload mass 𝑎∗ (𝑡) is the vertical global acceleration acting on 𝑚 𝑃 F(t)
  8. 8. Governing Equations ൝ 𝑀 ሷ𝑢 + 𝐶 ሶ𝑢 + 𝐾 𝑢 = 𝐹(𝑡) 𝑚 𝑃 ሷ𝑦 + 𝑘 𝑠 𝑦 − 𝑤 𝑦(𝑥 𝑇, 𝑡) = 0 𝑀 + 𝑚 𝑇 𝑁 𝑦 𝑇 𝑁 𝑦 0 0 𝑚 𝑃 ቊ ቋ ሷ𝑢 ሷ𝑦 + 𝐶 0 0 0 ቊ ቋ ሶ𝑢 ሶ𝑦 + 𝐾 + 𝑘 𝑠 𝑁 𝑦 𝑇 𝑁𝑦 −𝑘 𝑠 𝑁𝑦 𝑇 −𝑘 𝑠 𝑁𝑦 𝑘 𝑠 𝑢 𝑦 = = 𝑚 𝑇 𝑔 + 𝑚 𝑃 ∙ 𝑎∗(𝑡) 𝑁 𝑦 𝑇 0
  9. 9. Acceleration Profile A g t0 t0 Dt gf2 (a) (b) 𝑎∗ 𝑡 = 𝑔 ∙ ϕ2 ∙ 𝑠𝑖𝑛 2𝜋 4Δ𝑡 (𝑡0 − 𝑡)
  10. 10. Acceleration Profile B g t0 t0 tA g+ah (a) (b) VH from zero to constant speed
  11. 11. Acceleration Profile C g t0
  12. 12. Comparison: External force Parameters Trolley mass (kg) 90000 Profile A f2=1.66 Profile B tA=0.31 s Payload mass (kg) 85000 Dt=0.4s
  13. 13. Comparison: Vertical displacement Base Line Profile A Profile B Profile C Max Deflection (m) 0.496 0.667 0.655 0.543
  14. 14. Comparison: Vertical bending stress Base Line Profile A Profile B Profile C 1.32 1.73 1.71 1.41 𝐷𝐴𝐹 = 𝑚𝑎𝑥𝑖𝑚𝑢𝑚 𝑑𝑦𝑛𝑎𝑚𝑖𝑐 𝑟𝑒𝑠𝑝𝑜𝑛𝑠𝑒 𝑚𝑎𝑥𝑖𝑚𝑢𝑚 𝑠𝑡𝑎𝑡𝑖𝑐 𝑟𝑒𝑠𝑝𝑜𝑛𝑠𝑒
  15. 15. Conclusions • The behaviour presented by the standard, when hoisting a grounded load, is related to the initiation of the hoisting operation. In more detail, the variation in the hoisting speed dominates the response and hence the Dynamic Amplification Factor. • In addition, for the cases considered the amplification factor 𝜙2 underestimated the response when applied to the payload in a static analysis. • Since the impact that hoisting operation have on the dynamic response of these structures, it is worth to carry out transient dynamic analysis, even though in a simplified form. • Finally, the adoption of simplified profile for the external applied force, such as the Force Profile B presented here, would allow to carry out a more realistic and accurate analysis than the standard static analysis, but maintaining a certain degree of simplicity.
  16. 16. The TRUSS ITN project (http://trussitn.eu) has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 642453 Thanks for your attention

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