What is the significance of joint stiffness in bolted connections?

Joint stiffness determines how external loads are shared between bolt and clamped members. The bolt stiffness Kb = Ab.Eb/Lb and member stiffness Km (calculated using pressure cone method) affect load distribution. Load factor C = Kb/(Kb+Km), typically 0.15-0.25. External load on bolt = C x External Load. Higher member stiffness means lower portion of external load goes to bolt, reducing fatigue. This analysis is critical for fatigue-loaded joints like cylinder heads.