Chapter 16 wind design criteria, seismic design categories, risk categories, coordination with ASCE 7.
3
hours
0.3
CEUs
Codes and Standards
1.7.3
This course covers material relevant to the following ICC certification exams:
Chapter 16 wind design criteria, seismic design categories, risk categories, coordination with ASCE 7.
Format
On-Demand Online
Delivery
Self-Paced
Access
24/7 After Enrollment
Certification
Certificate of Completion
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Contact our support teamDetermine seismic design category and risk category for building projects
Gravity loads are the easy part of structural design to picture: the weight of a building simply presses straight down, and most people have an intuitive sense of what "heavy" means. Wind and seismic forces are harder, because they push and shake a building sideways rather than down, and lateral behavior is where the analysis gets genuinely complex and where most structural failures actually originate. That is why risk category and seismic design category determination sit at the front of this course: everything downstream — which analysis approach applies, how much detailing rigor is expected, what triggers special inspection — flows from decisions made here.
Risk category is a grouping exercise. It sorts buildings by the consequences of a structural failure rather than by their size or cost: an ordinary building, one that would pose a substantial hazard to the public if it failed, and one that must remain operational after a design event because the community depends on it for emergency response are treated differently precisely because the cost of getting the design wrong differs in each case. Seismic design category works the same way, one layer down — it is a named risk grouping, not a value to look up and move past. It reflects how demanding earthquake shaking is expected to be at a site, combined with how serious the consequences of a failure at that site and occupancy would be, and that combined grouping is what determines how much analytical rigor and detailing discipline the code expects. A reviewer's job is to confirm the stated category is consistent with the site and occupancy information elsewhere in the submittal — that calculation itself belongs to the engineer of record.
A reliable workflow begins with intake screening that establishes occupancy and risk category before any structural sheet is opened, continues through discipline coordination checking that structural, life-safety, and nonstructural anchorage share the same assumptions, and ends with field verification tied back to approved documents.
Consider an essential facility — a hospital or fire station — sited where seismic activity is a real design driver. Because its risk category is elevated, the code expects stricter design and detailing than an ordinary building of similar size would receive. A high-quality review confirms that the risk category shown on the cover sheet, the structural general notes, and the life-safety plans all agree, then traces how that classification carries through the rest of the submittal, including anchorage detailing for mechanical and other nonstructural components that the facility depends on to keep functioning, not just stay standing.
In inspections, field staff carry those same assumptions forward, confirming installed connections and anchorage match what was approved rather than a value-engineered substitution that quietly walks the project back toward ordinary-building detailing. When a field change appears, trace it back to the risk category assumption it touches and require documentation that the substitution still satisfies that assumption.
The most common failure is treating risk category as an administrative field rather than the input that drives the entire lateral design — confirming occupancy without checking whether structural and nonstructural details reflect that risk category. A second is accepting a late occupancy change, such as adding a shelter function, without recognizing it may raise the risk category. A third is inconsistency across the document set, where the cover sheet and structural notes imply different classifications that no one has reconciled.
The correction method is to reset the decision tree whenever risk category is in question: confirm the occupancy and function driving the classification, verify every affected discipline reflects the same classification, and require a coordinated update package whenever the classification changes.
Code Reference: IBC Section 1604.5 and Section 1613 - Establishes risk categorization and seismic design framework.
Apply wind design criteria and calculate wind loads using ASCE 7
Wind design is easiest to understand as a pressure problem: moving air striking a building creates pressure where it pushes against a surface and suction where it pulls away from one. The windward face generally experiences positive pressure pushing inward, while the leeward and side walls, along with much of the roof, typically experience suction pulling outward. That asymmetry is why a building envelope has to be designed as a whole system rather than a single uniform pressure applied everywhere. Building shape, height, and exposure change how severely a structure experiences those effects — a taller building sits higher in the wind profile than a low-rise building of similar footprint, a building in open exposed terrain behaves differently than one sheltered by surrounding structures, and an unusually shaped building can experience localized effects a simple rectangular box would not.
A second core concept is the distinction between the main wind-force-resisting system and components and cladding. The main wind-force-resisting system concerns the cumulative effect of wind on the building as a whole — the combined pressures the overall structural frame resists to stay upright and in place. Components and cladding are evaluated individually instead, because a single window, wall panel, or section of roofing can experience a much higher localized pressure — particularly near corners, ridges, and eaves — than the building-wide average would suggest. A design that only addresses the whole-building system and never checks individual cladding elements has addressed only half the wind design problem.
Roof uplift is the classic wind-related failure mode: suction acting on a roof surface tries to lift it away from the structure beneath it, and when fastening or attachment cannot resist that uplift, the result is often a dramatic, highly visible failure. That is why roofing attachment and roof-mounted equipment anchorage are such a frequent focus of both design review and field inspection. Reviewers also need to recognize the site-specific reality of wind design: the wind speed, exposure category, and other site parameters that drive a project's pressures come from maps and data specific to that building's location and terrain. The reviewer's role is not to independently derive those values but to verify that the parameters used correspond to the correct site and building characteristics, and were applied consistently across structural, envelope, and component-level calculations.
Consider a coastal project where the site's wind exposure and the building's enclosure classification — enclosed, partially enclosed, or open — materially change the pressures assigned to cladding and components. A high-quality review confirms the exposure and enclosure classification shown in the general notes match actual site conditions and the glazing and opening layout, then traces how those classifications flow into pressures used for windows, doors, and roofing. If later drawings show additional openings — a larger glazed storefront, added louvers — the reviewer should recognize that change can shift the enclosure classification even though the overall building form hasn't changed.
In inspections, staff should confirm the roofing, glazing, and attachment details actually installed match what plan review approved, treating a field substitution as a change requiring re-evaluation rather than a like-for-like swap.
A frequent mistake is applying a single wind pressure value uniformly across a building without rechecking exposure and enclosure assumptions, since a corner zone or an area near a large opening can experience meaningfully different demands than the building's general field. A second is treating a main wind-force-resisting system analysis as if it also covers components and cladding, when the two are related but distinct checks. A third is missing that a late change to a building's openings altered the enclosure classification the original component pressures were based on.
The correction approach mirrors Module 1: confirm the governing exposure and enclosure classification, verify both the whole-building system and individual components have been addressed, and require a coordinated update whenever an opening or roofing change could shift those classifications.
Code Reference: IBC Section 1609 with ASCE 7 wind provisions - Determines wind speed, exposure, and pressure requirements.
Understand equivalent lateral force and modal response spectrum procedures
Where wind is driven by moving air pushing against a building's surfaces, seismic demand comes from inside the building itself. An earthquake shakes the ground, and it is the building's own mass — resisting that ground motion as it tries to move with the shaking — that generates the internal forces the structure has to resist. That explains why heavier, taller, and irregular buildings tend to experience more severe seismic demands than lighter, shorter, regular ones: more mass means more inertial force, and irregular geometry tends to concentrate that force at specific points rather than distributing it evenly.
Reviewers should think of the lateral-force-resisting system in terms of three broad families. Shear walls are planar wall elements that resist lateral force largely through in-plane strength and stiffness. Braced frames use diagonal members, carrying lateral force primarily as tension and compression along those diagonals. Moment frames resist lateral force differently, relying on rigid beam-column connections so the frame bends as a unit rather than depending on diagonal bracing or wall panels. None of these families is inherently better — the right choice depends on geometry, use, and architectural constraints — but a reviewer should recognize which family a design uses and understand, in concept, how it behaves.
Whichever family is chosen, the concept that matters most is the continuous load path. The lateral-force-resisting system is a chain running from the roof and floor diaphragms, through the vertical elements, down to the foundation. A break anywhere in that chain, no matter how well every other piece is detailed, can defeat the whole system, because lateral force that cannot complete its path to the ground has nowhere reliable to go. Tracing that path on the drawings, level by level, is one of the single most valuable things a structural plan reviewer can do.
Detailing matters as much as member size. The code's detailing requirements exist to give a structure the ability to bend and absorb energy rather than fail suddenly and without warning — a concept generally described as ductility. A connection sized correctly for strength but detailed without adequate ductility can still perform poorly in an earthquake, because the goal is surviving actual, unpredictable motion rather than just resisting a calculated force. Irregularities — configurations where mass, stiffness, or the lateral system is not distributed evenly through the plan or up the height of a building — deserve particular scrutiny because they concentrate demand at specific locations: a discontinuous wall that stops at one level and picks up offset from where it left off is a classic example. Because lateral systems carry such significant life-safety consequences, projects involving them frequently require special inspection during construction — a topic covered in more depth in this platform's special inspections course — to confirm what gets built matches what was approved.
Picture a review where the drawings show a well-detailed shear wall on the upper floors, sized correctly according to the structural notes. Rather than stopping at that sheet, the reviewer traces the load path the wall is part of: where does the force it collects actually go once it reaches the floor below? Tracing downward reveals the wall stops at an intermediate floor, and the framing plan below shows no clear, detailed connection carrying that load down to a footing or foundation wall — the wall ends in mid-air structurally, even though it looks complete on its own sheet.
That is a load-path break, and it is exactly the kind of problem a sheet-by-sheet review focused on individual elements will miss. Flagging it before construction begins is what tracing the continuous load path is for. The correction is not simply adding strength to the wall itself; it is detailing an actual connection carrying that force the rest of the way to the ground and confirming the design criteria, framing plans, and foundation plan all agree once that connection is added.
The most consequential mistake in seismic review is evaluating lateral elements in isolation — checking that a shear wall or frame is adequately sized where it appears without tracing whether it connects, level by level, to the foundation. A second is accepting a design criteria statement naming a lateral system without verifying the framing plans show that system consistently at every level. A third is focusing on member sizing while overlooking connections and anchorage at the ends of the load path — roof-to-wall, floor-to-wall, wall-to-foundation — which is precisely where uplift and shear are transferred, and where structural plan review needs to look most carefully.
The correction method is to reset the decision tree: confirm the lateral system named in the design criteria, trace its continuity through every level, and verify the connections at each transition point. Design responsibility rests with the engineer of record, but a reviewer who can trace a load path and spot where it breaks is often the last check before an incomplete system gets built.
Code Reference: IBC Chapter 16 and ASCE 7 seismic procedures - Coordinates lateral system selection, detailing, and documentation.
IBC Wind and Seismic Design Provisions requires more than checking isolated details. Wind and seismic are the two lateral-load problems that make structural design genuinely difficult, because both push and shake a building sideways rather than simply loading it downward, and both are where the analysis complexity and failure risk are concentrated. Risk category and seismic design category set the stage by grouping a project according to the consequences of failure and the demands of its site; wind design works through pressure and suction on the building envelope, distinguishing whole-building from individual-component effects; and seismic design centers on tracing a continuous load path through a chosen lateral-force-resisting system, with detailing and connections carrying as much weight as raw member size.
Across all three areas, the reviewer's role is consistent: confirm the design criteria stated on the drawings — risk category, wind and seismic parameters, and the lateral system selected — are present, internally consistent, and reflected accurately in every discipline's documents, and trace the load path rather than trusting that a well-detailed piece on one sheet is automatically connected to a well-detailed piece on the next. The engineer of record carries design responsibility for the underlying calculations and site-specific parameters; the reviewer's job is to verify presence, consistency, and continuity, coordinate with structural plan review where the depth of verification exceeds a general review, and flag the classic gaps — a discontinuous load path, missing or inconsistent design parameters, unaddressed irregularities, and overlooked uplift or anchorage — before they become field problems.
The strongest teams use structured communication, documented assumptions, and disciplined closeout practices to keep projects aligned from intake through final approval. Applying that approach to wind and seismic design strengthens professional competency, supports predictable enforcement, and improves long-term building performance in the kinds of events these provisions exist to prepare for.