3- Building Construction- Structural Design Features of Buildings Flashcards
The forces within a structural support system that resist applied loads are referred to as _____ (R).
Reactions
When a structural support system can support a load equal to or greater than the applied loads (L), ________ exists.
Equilibrium
The force of ______ is the most common load imposed on a structure via the weight of the structure’s components, contents, and any occupancy activity.
Gravity
Stresses within a material are classified according to the ______ of the force.
Direction
____ stress pulls the material apart.
Tension
*aka tensile stress
____ stress squeezes the material.
Compression
*aka compressive stress
_____ stress slides one plane of a material past an adjacent plane.
Shear
Unique stresses are caused by external load alignments, including the following (three) loads:
Axial Load
Eccentric Load
Torsional Load
______ is a load applied to the CENTER of the cross-section of a member and perpendicular to that cross-section. Can be either tensile or compressive. Creates uniform stresses across the cross-section of the material.
Axial Load
______ is a load perpendicular to the cross-section of the structural member, but which DOES NOT PASS THROUGH THE CENTER of the cross-section. Creates stresses that vary across the cross-section and may be both tensile and compressive.
Eccentric Load
______ is a load applied OFF-CENTER from the cross-section of the structural component and at an angle to or in the same plane as the cross-section. Produces a twisting effect that creates shear stresses in a material.
Torsional Load
A ____ Load is fixed in location and quantifiable.
Dead
A ____ Load is not fixed or permanent, and the actual weight and distribution of them are often not quantifiable.
Live
____ Loads are steady or are applied gradually. Dead loads are generally this type of load. Many types of live loads are also this type of load too.
Static
____ Loads involve motion and are capable of delivering energy greatly in excess of the weight of the object involved. These loads may cause structural failure.
Dynamic
_____ Loads produce highly localized forces and non-uniform loads in the supporting structural members.
Concentrated
Rain and Snow are _____ Loads.
Live
Water from firefighting operations can add an additional live load to a building. This load may be ____ as fire flow, or ____ as accumulated water.
Dynamic ; Static
In some cases involving fires in high-rise buildings, dewatering operations will be necessary because water at a depth of 3” adds a static load of __ pounds per square foot.
21
The ____ energy of air manifests as wind that presents a force that can be calculated.
Kinetic
In designing buildings to withstand wind forces, ________ is used as the primary consideration.
Direct Pressure
Some places have a higher probability of seismic events during a __ year period - the typical expected “life span” of a building.
50
____ Loads that create horizontal motion are the most significant force generated by an earthquake.
Lateral
________ isolates the building from the horizontal movement of the earth’s surface. This strategy is increasingly popular and includes two common methods: Shear Systems and Sliding Systems.
Base Isolation
Soil exerts a ____ load (pressure) against a foundation.
Lateral
A ____ is a structural member that carries loads perpendicular to its longitudinal dimension. Their primary design consideration is their ability to resist being deformed from the applied loads.
Beam
Common support systems for beams include:
______ Beams: Supported beneath both ends and free to rotate. A wood joist resting on a masonry wall is an example.
Simply Supported
Common support systems for beams include:
_____ Beams: Rigidly supported at each end. Retains its load-bearing ability well because the end restraints provide more resistance to the applied stresses.
Restrained
Common support systems for beams include:
_____ Beams: Supported at one end; must be able to support a vertical load in addition to resisting bending stresses. They often support balconies.
Cantilever
Common support systems for beams include:
_____ Beams: Similar to cantilever beams but with addition support.
Overhanging
Common support systems for beams include:
_____ Beams: May span several vertical supports.
Continuous
The top _____ of a beam carries compressive stresses, while the bottom _____ of the beam carries tensile stresses.
Flange
When it comes to beams, the center horizontal line of the ___ is known as the neutral axis because the tension and compression stresses are zero, but the neutral axis is the maximum point of sheer stress.
Web
Tall beams are capable of supporting _____ loads than short beams, even if they have the same cross-sectional area.
Greater
_____ are structural members designed to support an axial load. The stresses created within them are primarily compressive.
Columns
Tall, thin columns fail by _____; short, squat columns fail by _____.
Buckling ; Crushing
An _____ is a curved structural member with primarily compressive interior stresses.
Arch
Although a _____ is essentially straight, one used to support loads over a distance will assume a curved shape. Stresses in them are tension stresses.
Cable
_____ are framed structural units made up of a group of triangles in one plane. A true one is made of only straight members.
Trusses
The top and bottom members of a truss are called _____. The middle section of a truss is also called the _____ or diagonals.
Chords ; Web
Typical truss shapes span distances of __ to __ feet, but truss spans in modern construction may exceed ___ feet.
22 to 70 ; 100
Some types of roof trusses, such as the _____ truss, have a curved top chord. These curbed members are unavoidably subjected to bending stresses.
Bowstring
Lightweight steel trusses, known as _____, are used for floor and roof construction in fire-resistive and noncombustible construction.
Bar Joists
______ are three-dimensional truss structures. They are well-suited to support uniformly distributed loads.
Space Frames
_____ are commonly placed at the exterior of a structure, but they may also include internal walls. They carry compressive loads and provide lateral support to the structure along the length of the wall.
Load-Bearing Walls
A _____ structure uses structural supports in a manner similar to the way the skeleton supports the human body. (the walls act as the ‘skin’ to enclose the frame)
Frame
- “frame construction” often refers to a wood-frame building, but frame structural systems are also built using other materials
___ __ wall construction includes frames built from relatively closely spaced vertical ___ __s connected by top and bottom horizontal members.
Steel Stud
In steel stud wall construction, studs are placed __ to __ inches apart.
12 to 16”
____ and ____ construction framing uses a series of vertical elements to support horizontal elements that carry TRANSVERSE loads. It requires the addition of other members, such as diagonal braces, to withstand lateral loads.
Post and Beam
*Vertical elements = posts
*Horizontal elements = beams
The distinctive characteristic of post and beam framing is the spacing of the vertical posts and the cross-sectional dimension of the members, because the dimensions are often _____ than used in stud wall construction.
Greater
*For example, posts may be 6x8” when supporting roofs only.
A ____ ____ structural system is characterized by columns and beams reinforced to transmit the bending stress through the joints. Often single story in height with a gabled roof.
Rigid Frame
One common concrete framing system uses concrete floor slabs supported by concrete columns. (Slab and column frames) Because of the high stress load at the connection, the intersection between the slab and column is usually reinforced by additional material in the form of a _____ or a ___ ____.
Capital ; Drop Panel
*Capital at top of column, drop panel between capital and slab.
Slab
Drop Panel
Capital
Column
Slab
