Information summarized from the Marinaro Document “ARE STRUCTURAL SYSTEMS 101”
Pre-Test Outline created by Arch Exam Academy
Leading up to the Exam: Preparation
There is the right way, the wrong way and the NCARB way.
Before entering the test room decide what to use for span limits. If you do not, you will waste time debating with yourself what to do.
Read the program with great care and make notes. NCARB may change to the program at any time without notice. You must read it with care.
One major error or many minor errors will cause a fail. Therefore, minimize errors by not taking risks:
Run through and practice until you can complete it in the allotted time.
Review the full Marinaro Document “ARE STRUCTURAL SYSTEMS 101” to understand why “Spanning the joists the short direction of the roof is more efficient even though the span is 40′!”
Print and Look Over Within an Hour Before the Exam: Review
- Draw elements on the correct layer, lower roof and upper roof
- Use an all steel solution (this was difficult for me because I do load-bearing masonry design on a regular basis.
- Use simple span beams not continuous beams. People have stated that it is faster to draw continuous beams. If you cannot finish on time or early using simple span beams, you are not ready for the test.
- Place a beam under the clerestory
- Span joists the short direction of the upper roof.
- Always place a beam in the walls between the low and high roof
- Do not rely on the number of beams and columns as a guide to economy
– Place columns in the center of the wall to provide economical beam lengths
– Place one in every corner
– Do not spend 30 minutes to determine where to place columns
– Add more later in the exam if it’s necessary to shorten the spans of the beams
– Columns supporting high roof must be supported at the low roof by a column or loadbearing wall
– Designate it as loadbearing
– Do NOT support a column on a beam
– WATCH FOR the program to explicitly state to not put columns in a window wall
– If you are not sure what the extent of the window wall err on the conservative side
– In the real world, columns cost less than beams so do not skimp on columns
– Use only simple span beams
– The program does not explicitly state that continuous beams are acceptable (therefore carries risk)
– Beam spans should be parallel with the long dimension of rectangular building
– Be wary of exceptions to this in the vignette.
– Draw beams from center of column to center of columns
– Beams should only frame into columns
– Do NOT frame a beam on another beam, it may be an error
– Place a beam where walls extend up to the high roof
– All columns are in walls the beams are also in and parallel to the wall
– No need for long spans except maybe at the opening that is required to be column free
– 40-foot beams
– Adding a column on each side of the opening
– Girders spanning 30 feet are less expensive than beams spanning 40 feet (reduce steel cost)
– Do NOT limit beam spans if it causes you to violate an explicit program requirement.
– Do NOT try to achieve 40-foot spans for all of the beams.
– 40-foot long beams are excessive to support 12-foot long joists
– Adding columns to reduce beam spans from 40 to 30 foot improves system economy
– If the two-story space has an exterior wall, you do not need to place a beam along the exterior wall at the low roof level
– The program will state the maximum deck span
– The deck span determines the joist spacing
– Use a joist spacing that matches the maximum span for the deck
– Do NOT use a joist spacing less than the maximum deck span (fatal error)
– Joists are placed by drawing rectangles
– Start at the centerline of a column and end at the centerline of a column
– Joists MUST NOT cross over a beam
– There may be scenarios where you must add a column to allow the joist rectangle to end at a column Adding a column may not be required but should not be an error. Not adding a column may be an error
– At the walls between the high and low roof there will be either a beam or a joist in the wall
– Both start and stop at the centerline of the column and the columns must be in walls
– If there is a joist in the wall, it disrupts the support for the wall above the low roof
– Place a beam over the joist to support the wall
– Joists may not support the weight of the wall above them
– Draw the beam on the low roof plan
– Beams that support joists have the capacity to support the wall above them
– The program does not dictate a maximum span for joist
– For an economical design the joist spans should be acceptable
– The high roof is the only area where there are questions about the maximum spans for joists
– Assuming the high roof area is rectangular
– ALWAYS span the joists the short dimension of the room
– It is not economical to add one or more 33 ft beams to reduce joist span from 33 to less than 30 – Turning joists reduces their length but increases the quantity of joists (increasing erection costs)
– Not spanning the joists the short direction of the room is an error
– Joists do not need to line up at across a beam
– The deck tool uses a rectangle for placement
– The rectangle must start and stop at the centerline of a column
– The rectangle can go over a line of beams as long as the joists span the same direction
– Be sure to change the direction of the deck span if the joist span changes direction.
The directions (not the program) states “…should be structurally sound, efficient and responsive to program requirements.” The definition of efficient I found on the web (and therefore must be true) is “achieving maximum productivity with minimum wasted effort or expense.”
No information is given as to what an “efficient” should include or exclude. Spanning the joists the short direction of the roof is more efficient even though the span is 40′ (learn the details of this point with your other preparation – not suitable for pre-test review).