GIDPC.Green Infrastructure · Disaster Prevention
Research & Technology
TreesUnder Review

Fatigue Life Assessment of Urban Street Trees under Wind Loading: Effects of Decay Progression and Soil Conditions

An integrated framework — ABAQUS dynamic FE, Kaimal-spectrum wind, rainflow counting, Miner's rule, and regional Weibull wind distributions — that quantifies street-tree fatigue life under decay progression and soil conditions.

Authors
Junsuk Kang
Year
2026
Funding
Korean Ministry of Environment R&D 2022003570004

Keywords

tree risk assessmentwind-induced fatiguefinite element dynamic analysisdecay stress amplificationWeibull wind distribution

Background

Urban street trees pose serious hazards to pedestrians, vehicles, and infrastructure during storms via branch failure and windthrow. Existing risk frameworks focus on static ultimate-load criteria and neglect cumulative fatigue from everyday wind loading.

Method

Six integrated modules:

  1. FE dynamic analysis (ABAQUS) — six geometries, B31 tapered beams
  2. Kaimal-spectrum wind time series — longitudinal mean+turbulence + lateral turbulence (σv = 0.75σu)
  3. Rayleigh damping (ζ = 2%)
  4. Rainflow + Miner's linear damage rule
  5. Concentric-hollow decay stress amplification (Mattheck & Breloer 1994)
  6. Regional Weibull wind speed distributions

Key Results

| Metric | Value | |---|---| | Maximum dynamic amplification factor (DAF) | 7.71 (H=8 m, DBH=15 cm) | | Peak stress (same condition) | 138.7 MPa (exceeds ginkgo MOR) | | Lower-bound fatigue life for decayed reference tree (Jeju typhoon) | ~1.4 yr | | Sound-tree fatigue life spread across 5 Korean species | up to several hundred thousand-fold | | Basal-stress reduction in soft clay | up to −64.5% |

Significance

Slender trees fail statically before fatigue, and decay detection plus species selection are the primary determinants of fatigue safety. The study quantitatively justifies regionally differentiated inspection standards.

Research & Technology