SE Exam common mistakes
SE Exam · Understand the traps and how to avoid them.
Sizing a beam or slab for flexural strength and then moving straight to the next member without running the shear check or the serviceability deflection check.
Under time pressure the flexure equation feels like the 'real' answer, and deflection is treated as a formality that can be eyeballed. Candidates also forget that the deflection limit depends on whether the member carries brittle or non-brittle finishes.
What to do instead
Before starting any member, draw a four-box checklist - flexure, shear, deflection, and (where applicable) vibration or camber - and physically tick each box. Write the governing deflection limit (L/360, L/240, etc.) next to the box before you compute anything.
Running only one or two gravity load combinations (typically 1.2D+1.6L) and never checking combinations involving S, R, or the 0.9D uplift case.
The candidate builds the combination set from memory of a single familiar case rather than from the code table, and self-weight of the member is often omitted from D.
What to do instead
At the start of the problem, write out the full combination matrix from the governing code, including the 0.9D case, and identify which combination controls for the specific limit state (flexure vs. shear vs. uplift). Include member self-weight explicitly in D.
Mixing foot-pound and inch-pound units inside a single calculation - moments carried in kip-ft while section modulus is in in³, or spans in feet plugged into an inches-based formula.
Code tables and span inputs are habitually in feet while steel and concrete section properties are in inches, and the conversion gets lost partway through a page of arithmetic.
What to do instead
Convert every input to kips and inches at the intake step and write the converted values in a small box at the top of the page. Carry units through every line of the calculation and only convert the final answer back to kip-ft for presentation.
Assigning tributary areas by visual inspection of the framing plan without a scaled sketch, producing missed or double-counted wall, partition, and cladding loads.
One-way versus two-way action is decided from memory of the previous problem, and the difference between tributary area and influence area is blurred.
What to do instead
Sketch the tributary polygon to scale directly on the plan, shade it, and label the tributary width and length. Separately list line loads (walls, cladding, parapets) with their own lengths and confirm none appear in two places.
Applying live load reduction to members or occupancies that do not permit it (roof live load, storage, passenger vehicle), or exceeding the permitted reduction limit, or using gross area instead of KLL·AT.
The reduction factor is memorized as a single formula and the conditional clauses - minimum live load, tributary-area threshold, occupancy exclusions - are skipped under time pressure.
What to do instead
Before invoking any reduction, write the three code conditions you must satisfy (occupancy eligible, KLL·AT value, and the floor value of the reduced load) and check each one explicitly. If any condition fails, use the unreduced load without further comment.
Checking lateral members or the lateral system for strength only and never computing story drift, including the Cd amplification, or never evaluating the stability coefficient for P-delta.
Strength feels like the exam's question, and drift is treated as a serviceability afterthought; the Cd factor is easy to forget because it appears only in the drift expression.
What to do instead
Treat drift as a separate, mandatory deliverable: for every lateral-force problem, write the drift limit, the amplified drift expression with Cd, and a stability-coefficient check with the θ ≤ 0.10 shortcut before touching member design.
Omitting accidental torsion in the lateral analysis, or applying the 5% offset in one direction and one sign only.
The problem statement often gives a clean symmetric plan, so torsion looks irrelevant; when it is applied, only the '+' case is run because the '−' case feels redundant.
What to do instead
Make '±5% accidental eccentricity in each orthogonal direction' a fixed line in your lateral setup, and run both signs. Note which sign produces the larger shear in each vertical element before designing that element.
Treating the diaphragm force as if it were the story shear and never computing chord forces, collector forces, or the connection of the lateral system to the diaphragm.
The lateral analysis is mentally equated with 'find the base shear and distribute it,' so the load path below the diaphragm level is left unfinished.
What to do instead
After obtaining the story shears, write an explicit load-path chain - inertial force → diaphragm → collector/chord → vertical lateral-force-resisting element → foundation - and compute the chord and collector demands as their own step before designing anything.
Using the wrong response modification factor, deflection amplification factor, or overstrength factor for the chosen lateral system, or pairing the seismic load with the wrong load combination (strength 1.2D+1.0E versus ASD 0.7D+0.7E).
R, Cd, and Ω0 sit in a table with many similar-looking rows, and the design-method label at the top of the problem is easily overlooked.
What to do instead
First line of every seismic problem: state the design method (ASD or LRFD), the lateral system by name, and copy the corresponding R, Cd, and Ω0 values with the table reference next to them. Only then build load combinations.
Skipping the irregularity checks and defaulting to the equivalent lateral force procedure, or forgetting to include the redundancy factor where it is required.
The plan looks regular at a glance, and the irregularity criteria are qualitative enough that a candidate assumes compliance rather than verifying it.
What to do instead
Keep a short irregularity screening table (torsional, extreme torsional, re-entrant corner, soft story, weight/mass, vertical geometric, in-plane discontinuity) and mark pass/fail with the computed ratio for each. Use the result to justify the chosen analysis procedure and the redundancy factor explicitly.