Original PE Civil worked example
Temporary shore reactions: tributary area and load path
Calculate an original shore reaction, identify plausible unit and load omissions, and separate reaction calculation from capacity and bracing checks.
Reviewed for the current ReasonSpan™ exam profile · Updated October 10, 2026By the ReasonSpan™ editorial team · Our content standards
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Original exercise: a temporary shore carries a 4 ft by 5 ft tributary area. The exercise supplies a combined construction load of 160 psf and an additional 0.40-kip concentrated load at the shore. Find the unfactored reaction; do not assume that this calculation alone establishes shore capacity or code compliance.
The tributary area is 20 square feet. The distributed contribution is 3,200 lb, or 3.20 kip; adding 0.40 kip gives 3.60 kip. A calculation of 3.20 kip omits the concentrated load, while 320 kip mishandles the pounds-to-kips conversion. Capacity, bracing, connection details and the applicable construction-load provisions are separate checks.
Trace the load to the support
| Check | Exercise evidence | Decision |
|---|---|---|
| Tributary area | 4 ft × 5 ft | Use 20 ft², not the whole slab area. |
| Distributed load | 160 lb/ft² | Multiply by area before converting lb to kip. |
| Concentrated contribution | 0.40 kip at this shore | Add it once to this support. |
| Capacity and stability | Not supplied | Do not conclude that the shore is adequate from demand alone. |
Try a changed condition without copying the answer
Keep the supplied 160-psf load and 0.40-kip concentrated contribution, but change the tributary rectangle to 3 ft by 6 ft. Calculate before reading: distributed demand is 160 × 18 = 2,880 lb, and total reaction is 3.28 kip. The shorter width does not automatically mean lower demand; use the area and the actual load path.
If the concentrated load transfers through a different support, the reaction at this shore changes. Do not distribute it equally among nearby shores without a stated structural model. For the current Civil exam profile, consult the supplied construction-load and formwork references listed by NCEES; use their applicability and combinations only when the problem calls for them.
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Sources and further reading
Exam requirements can change. Confirm current details with the organization that administers your exam and use the cited sources for the preparation principles summarized here.