Free PE Civil: Structural Exam Flashcards

Multiply the area load by the beam's tributary width. The tributary boundaries normally fall midway between adjacent supports, so changing beam spacing changes the line load even when the area load is unchanged.

Every applied gravity or lateral load must pass through connected members, diaphragms or collectors, vertical resisting elements, foundations, and finally the ground. A strong member does not cure a missing connection anywhere along that chain.

The incomplete structure may have different supports, bracing, concrete strength, load distribution, and stability. A member or shore can govern during erection even when the completed structure easily resists its design occupancy loads.

MWFRS loads act on the primary system that stabilizes the whole structure. Components-and-cladding pressures design local elements and attachments such as roof panels, wall panels, and fasteners; their smaller effective wind areas can produce larger local pressures.

The effective seismic weight specified by the governing standard: principally permanent dead load plus required portions of other loads. Seismic force is inertia, so mass that participates in the motion must be represented rather than treating earthquake action as an unrelated applied pressure.

It shows how one response at a fixed location—such as a reaction, shear, or moment—varies as a unit load moves across the structure. Place positive loads over ordinates of the desired sign to maximize that response.

Wind can transport snow from an exposed upper area and deposit it against an obstruction or lower roof. The resulting nonuniform drift surcharge may exceed the balanced roof snow load locally and must be applied over the prescribed drift zone.

Active pressure develops when the wall moves sufficiently away from the soil; at-rest pressure applies when lateral strain is restrained; passive resistance develops when the wall pushes into the soil. Passive resistance generally requires much more movement than active pressure.

Strength combinations use factored loads to check ultimate limit states. Service combinations use service-level loads for deflection, drift, cracking, vibration, or soil-pressure checks. Comparing a factored demand to a service-level limit produces an inconsistent result.

At a point where shear crosses zero, provided there is no concentrated couple or discontinuity that controls instead. The slope of the moment diagram equals shear, so a zero shear marks a stationary value of moment.

Deformation compatibility and member stiffness, in addition to equilibrium. Reactions or internal forces cannot be found by equilibrium alone because redundant restraints create more unknowns than independent equilibrium equations.

A concentric axial force acting through the centroid and a sufficiently uniform stress distribution away from local disturbances. Eccentricity adds bending stress, so P/A alone is not valid for an eccentrically loaded member.

M is bending moment, y is distance from the neutral axis, and I is the second moment of area about that axis. Stress varies linearly through the depth and is largest at the extreme fibers while the section remains elastic.

Force transferred per unit length along an interface or through a thin-walled section. Multiplying q by fastener spacing gives the force assigned to a connector, subject to the connection's actual load path and code limits.

They act simultaneously at the same fibers. Concentric axial stress shifts the entire stress distribution, while bending adds tension on one side and compression on the other; the extreme combined demand can govern even if each separate check passes.

For the same load and geometry, deflection varies inversely with EI. Increasing elastic modulus E or second moment of area I reduces deflection, although cracking, creep, connection slip, or composite action may change the effective stiffness used.

Warping can create longitudinal normal stresses and additional restraint forces, especially when the member cannot warp freely. The torsional response depends on section shape, warping restraint, and load application relative to the shear center.

Elastic buckling capacity is proportional to flexural stiffness and inversely proportional to the square of effective length. Doubling KL cuts the Euler load to one quarter, which is why end restraint and bracing matter so strongly.

The cyclic stress range at the fatigue-sensitive detail, together with the number of cycles and detail category. A stress below yield can still initiate and grow a fatigue crack after enough repetitions.

It provides alternate load paths after a local element is lost or severely damaged. Redundancy does not prevent the initiating failure; it limits disproportionate spread by allowing surrounding members and connections to redistribute demand.

ΔL = αΔTL, where α is the coefficient of thermal expansion. If supports restrain that movement, thermal force or stress develops; using the free movement alone would miss the restraint effect.

Formwork shapes fresh concrete; falsework supports temporary construction such as an uncompleted span; shores support fresh or immature construction; reshores are installed as original shores are removed to distribute construction loads through lower levels.

Special inspection is detailed verification of specified materials, fabrication, and installation by qualified inspectors. Structural observation is the design professional's general review of significant structural construction for conformity with the design intent; it does not replace required inspection.

No. Review normally checks conformance with design intent and contract requirements, while the fabricator or specialty engineer retains responsibility assigned by the documents. Delegated design must have explicit criteria, scope, and professional responsibility.

The permanent lateral system may not yet be complete or connected, so stability changes at each stage. Bracing that works after the deck or diaphragm is installed may be inadequate while isolated frames, walls, or trusses are being erected.

Strength governs bearing-capacity or stability failure, while compressibility governs total and differential settlement. A foundation can have adequate resistance against shear failure yet still be unacceptable because settlement damages the structure.

Concrete has high compressive strength but relatively low tensile capacity and cracks after its tensile strength is exceeded. Reinforcement crosses the cracks and carries the required tension while concrete continues to provide compression and protection.

Prestressing introduces compression before service loads act, offsetting tensile stress and controlling cracking or deflection. Losses from elastic shortening, creep, shrinkage, relaxation, friction, or anchorage seating reduce the effective prestress.

Fy marks the onset of significant yielding, while Fu is the maximum tensile stress before rupture behavior governs. Different limit states use one or the other; substituting Fu for Fy can incorrectly overstate a yielding-controlled capacity.

Its thin plate elements can buckle before the full gross section reaches yield. Effective-width or direct-strength provisions account for local, distortional, and global buckling interaction rather than assuming the entire gross section remains effective.

Wood is orthotropic: strength and stiffness parallel to grain differ greatly from properties perpendicular to grain. Moisture, duration of load, member size, stability, and connection behavior also modify the usable design value.

Units form the wall, mortar bonds and transfers load at joints, grout fills designated cells and bonds reinforcement to the masonry, and reinforcement carries required tension and adds ductility. Mortar alone is not a substitute for grout around bars.

Flexure and shear are different failure mechanisms with different demand patterns and resistance models. Maximum moment often occurs away from maximum shear, so passing a bending check says nothing conclusive about web or diagonal-shear capacity.

A one-way slab sends most load across one principal span to two opposite supports. A two-way slab distributes meaningful bending in two directions to supports on multiple sides; geometry, support conditions, and relative stiffness determine the behavior.

Around a code-defined critical perimeter surrounding the loaded column or reaction area. It is a localized two-way failure mechanism, distinct from one-way beam shear checked across a section spanning the member width.

Chords resist the diaphragm's boundary tension and compression analogous to beam flanges. Collectors gather diaphragm shear and deliver it into vertical lateral-force-resisting elements, especially where those elements are discontinuous or offset.

Reliable lateral bracing and rotational restraint that stabilize the relevant buckling axis. A nearby member counts only if its stiffness, strength, connections, and load path can deliver the required brace force.

Axial load acting through lateral displacement creates additional P–Δ and P–δ moments. These second-order effects amplify demand beyond first-order moments and become more important as stiffness decreases or unsupported length increases.

A bearing wall principally supports gravity loads, while a shear wall is proportioned and detailed to resist in-plane lateral forces and overturning. One wall may perform both roles, in which case combined axial, flexural, and shear demands must be considered.

The ideal truss model assumes pin-connected members carrying axial force. Loads between joints introduce member bending that the axial-only analysis misses and may require the chord or web member to be designed for combined actions.

A braced frame uses primarily axial forces in diagonal braces and frame members. A moment frame relies on flexural stiffness and moment-resisting beam-column connections; the chosen system changes drift, force distribution, and connection detailing.

Longitudinal interface shear. Shear connectors restrain slip so the slab and beam develop compatible strain and a larger composite stiffness and strength than two unconnected elements.

Bolt bearing, net-section rupture, block shear, gross-section yielding, bolt tension, slip where required, and interaction of bolt shear and tension. The governing capacity is the lowest applicable resistance along a credible load path.

The force acts away from the weld group's centroid. The group must resist the direct force plus a moment equal to force times eccentricity, producing a nonuniform resultant demand around the weld pattern.

Enough embedment or anchorage for a reinforcing bar to transfer its required force into the surrounding concrete without bond failure. Bar size, coating, concrete strength, confinement, cover, spacing, and bar location can change the required length.

Closely spaced anchors can share load and create overlapping concrete breakout surfaces. Group geometry, edge distance, eccentricity, cracked concrete, installation qualification, and steel or bond failure can govern before an individual anchor's nominal strength.

If eccentricity e = M/P stays within B/6 about the checked axis, the linear elastic contact-pressure model remains compressive across the full base. Beyond B/6, that model predicts tension, so partial contact and a revised pressure distribution are needed.

Pile spacing and soil interaction can make the group act as a block, change load transfer, and increase settlement. The pile cap also distributes axial load and moment unevenly, so both individual-pile and group behavior must be checked.

Sliding, overturning, bearing pressure and bearing capacity, settlement, and global stability, plus structural design of the stem, base, and connections. Passing one ratio does not demonstrate that the other failure modes are safe.

Analysis forces exist only if plates, welds, bolts, anchors, reinforcement, and supporting material can transfer them through compatible deformations. A connection that omits eccentricity, collector force, restraint, or constructability invalidates the assumed system behavior.