Learning / bridge engineering
pilecap
Pile reaction redistribution
Lesson review: expert verification remains open
This lesson has received a full-context editorial review and a check of its technical explanations. Selected arithmetic has been checked separately. This is not independent engineering sign-off.
Checks needed for project use
- Bridge component studies and adjustable examples still need an independent bridge-engineering review, including applicability, load models and detailing guidance.
- Specialist review remains for: Use equilibrium for preliminary pile reactions, then a strut-and-tie model or suitable solid model for force transfer. Check whether assumed struts and ties physically fit. The pilecap calculation is a local idealisation; it does not verify the displayed bridge or applicable design requirements.
These are educational models and exercises. Check their assumptions before using the results. The full technical content and every diagram have not yet been independently verified.
Concrete and steel calculations retain their stated first-generation Eurocode teaching basis. Use the standards and amendments specified for your project; do not mix generations without an appropriate design basis.
Read the lesson register and outstanding review notesLoads and actions
The cap spreads column or wall loads into discrete piles and transfers moments through unequal pile reactions. Deep caps often behave as discontinuity regions.
Choose a model
Use equilibrium for preliminary pile reactions, then a strut-and-tie model or suitable solid model for force transfer. Check whether assumed struts and ties physically fit.
Design considerations
Arrange piles and ties around actual column and pile positions. Check nodal zones, punching/shear, anchorage, cover, pile tolerances and reinforcement congestion.
Durability and maintenance
Control cracking and construction joints. A buried cap is difficult to inspect; robust detailing and records of pile positions matter.
Pile reaction redistribution
Rigid cap, equal axial stiffness, no soil contact. Negative reaction indicates uplift demand, not proven tensile capacity.
Six equal-stiffness piles in two rows x = ±1.5 m; N = 6000 kN. Ri = N/6 + Mxi/Σx².
Pile reactions = 866.7 and 1133.3 kN (three in each row)