Glossary Of Structural Engineering

This glossary is dedicated to the intricate world of structural engineering and its various specialized branches. For a more expansive understanding of engineering concepts across the board, consult the Glossary of engineering.

While many of these terms are self-explanatory or defined within their own context, a comprehensive glossary like this serves as an invaluable resource for quick lookups, comparative analysis, and systematic review. You're welcome to contribute by adding new terms or refining existing definitions.

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• Abutment – This refers to the substructure found at the extremities of a bridge span or dam, acting as the crucial point where the superstructure rests or makes contact. It’s the anchor, the solid ground against which the forces are ultimately resolved. Think of it as the bridge's handshake with the earth.

• Acre – A unit of land measurement, deeply rooted in the imperial and US customary systems. Historically, it was defined as the area a yoke of oxen could plow in one day, precisely one chain by one furlong (equivalent to 66 by 660 feet). This translates to exactly 10 square chains, a mere 1/640th of a square mile, or 43,560 square feet. For those who prefer metric, that’s approximately 4,047 square meters, or roughly 40% of a hectare. It’s a unit that speaks of land, of ownership, of the tangible space we occupy.

• Acrow prop – More formally known as a BS prop, this is a piece of essential construction equipment. It's essentially a telescopic tubular steel prop, engineered for temporary support. Imagine a sturdy, adjustable crutch for buildings under construction or renovation. While similar in function to a jackscrew, it's typically longer and designed for telescopic adjustment. In places outside the UK, you might encounter it under various guises: a jack post, an adjustable post, telescoping prop, screw jack, adjustable steel column, adjustable steel prop, adjustable metal prop, or even an adjustable shoring post or shore post. It’s the unsung hero of temporary stability.

• Adhesion – This describes the tendency of dissimilar particles or surfaces to cling to one another. It’s the opposite of cohesion, which is the attraction between similar particles. The forces driving adhesion are varied, stemming from intermolecular interactions. We see this in the everyday magic of stickers and tape, where chemical, dispersive, and diffusive forces combine. Beyond these molecular attractions, there are also mechanical effects that contribute to adhesion. It’s the universe’s way of making things stick together, sometimes inconveniently.

• Aggregate (composite) – In the realm of composite materials, aggregate serves as the backbone, the component that bears the brunt of compressive stress and gives the composite its bulk. For optimal performance, aggregates should be significantly smaller than the final product, and ideally, present a diverse range of sizes. Think of the stone used in concrete; it’s a carefully chosen blend of sand and gravel, each size playing its part.

• Aggregate (construction) – This is a broad classification of particulate materials, ranging from coarse to medium grain, fundamental to construction. It encompasses sand, gravel, crushed stone, slag, and even recycled concrete and geosynthetic aggregates. It’s the granular foundation upon which so much of our built world is erected.

• Air conditioning – Commonly abbreviated as 'AC' or 'A/C', this is the process of actively removing heat and moisture from an interior space. The primary goal? To enhance occupant comfort. It’s a ubiquitous technology, found in both domestic homes and commercial establishments, silently orchestrating our climate.

• All-in ballast – Within the specific context of structural engineering, this refers to a pre-mixed aggregate of sharp sand and gravel, specifically formulated for the creation of concrete. The "all-in" moniker signifies that the components are already combined in the correct proportions, eliminating the need for separate sourcing and on-site mixing. It’s efficiency in granular form.

• Alloy – An alloy is a sophisticated blend, a combination of metals or a metal with another element. The defining characteristic is the presence of metallic bonding. Alloys can manifest as solid solutions, where elements are uniformly dispersed, or as mixtures of distinct metallic phases. Intermetallic compounds are a special class, possessing a defined stoichiometry and crystal structure. Even Zintl phases sometimes fall under this umbrella, depending on the nature of their bonding.

• American National Standards Institute – This is a private, non-profit organization that acts as the guardian of voluntary consensus standards in the United States. It oversees the development of these standards for products, services, processes, systems, and even personnel. Crucially, it also serves as a bridge, coordinating U.S. standards with international ones, ensuring American products can seamlessly integrate into the global marketplace.

• Annealing (metallurgy) – In the fields of metallurgy and materials science, annealing is a controlled heat treatment. Its purpose is to modify the physical, and sometimes chemical, properties of a material, specifically to enhance its ductility and reduce its hardness, thereby making it more amenable to processing and shaping. The process involves heating the material above its recrystallization temperature, holding it there for a specific duration, and then allowing it to cool. It's a way to soften and refine metals.

• ANSI – An acronym for the American National Standards Institute.

• Arch – A fundamental structural element, an arch is a vertical curved structure designed to span an elevated space. Its primary function is to support the weight above it, though in some cases, like an arch dam, it resists external forces like hydrostatic pressure. It’s a shape that has defied gravity for millennia.

• Arching or compressive membrane action in reinforced concrete slabs – This refers to a phenomenon where reinforced concrete slabs, under certain conditions, develop internal compressive forces that contribute to their load-carrying capacity, behaving in a manner similar to an arch.

• Architecture – Encompassing both the process and the final product, architecture is the art and science of planning, designing, and constructing buildings and other structures. Architectural works are often seen not just as functional spaces but as cultural symbols and works of art, with historical civilizations often defined by their enduring architectural legacies.

• Architectural engineering – This discipline integrates the principles of architectural design with the technical aspects of structural, mechanical, and electrical engineering.

• Architrave – Also known as an epistyle, this is the lintel or beam that sits directly atop the capitals of columns. It's a key feature in Classical architecture. The term can also describe the mouldings framing the top of a door or window opening, where the horizontal element extends across the top of the vertical ones, forming a butt joint rather than a miter joint. It’s the crowning element, the transition from vertical support to horizontal span.

• Ashlar – This denotes finely dressed, or worked, stone, either as individual blocks squared for precise fitting or as the structure built from them. Ashlar is the pinnacle of stone masonry, typically cuboid or sometimes trapezoidal. The stones are cut with extreme precision on all adjacent faces, allowing for remarkably thin joints. The visible face can be left with its natural quarry texture or be treated with various finishes, from tooling to smooth polishing, or even rendered for decorative purposes. It’s masonry elevated to an art form.

• Austenitization – This is a critical heat treatment process for iron, iron-based metals, and steels. It involves heating the material to a specific temperature range where its crystal structure transforms from ferrite to austenite. The more open austenite structure is then capable of absorbing carbon from iron-carbides. Incomplete austenitization can leave undissolved carbides within the material’s matrix, potentially affecting its properties. In some cases, a two-phase austenitization occurs, where both ferrite and austenite phases coexist. It’s a fundamental step in heat treating metals.

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• Ballast – This is material strategically employed to provide stability to vehicles or structures. In maritime contexts, ballast might be added to ships to improve stability. In aeronautics, gondolas of balloons and airships use ballast. It’s simply a means of adding weight for equilibrium.

• Barrier cable – A type of restraint system designed for vehicles or pedestrians. It typically consists of a steel strand, similar in construction to those used in post-tensioned concrete. It’s a safety measure, a physical deterrent.

• Beam – A fundamental structural element, a beam's primary role is to resist loads applied laterally to its axis. Its characteristic mode of deformation is bending. The applied loads induce reaction forces at the supports and internal shear forces and bending moments, which in turn create stresses, strains, and deflections. Beams are classified by their support conditions, cross-sectional shape, length, and material.

• Bearing capacity – This refers to the ability of soil to withstand applied loads. It’s the maximum average contact pressure a foundation can exert on the soil without causing shear failure. The ultimate bearing capacity is the theoretical maximum, while the allowable bearing capacity incorporates a factor of safety. In softer soils, settlement can be the limiting factor, even without shear failure. The three primary failure modes are general shear, local shear, and punching shear.

• Bending – In the field of applied mechanics, bending, or flexure, describes the behavior of a slender structural element when subjected to an external load applied perpendicular to its longitudinal axis. It’s the fundamental way beams deform under load.

• Bending moment – This is the internal reaction within a structural element caused by an external force or moment that induces bending. It’s a critical factor in structural analysis, directly influencing stresses and potential failure.

• Benefit–cost analysis – Often abbreviated as CBA, this is a systematic method for evaluating the strengths and weaknesses of different alternatives. The goal is to identify the option that yields the greatest benefits while minimizing costs. It's commonly applied to business transactions, policy decisions, and investment projects, providing a quantitative framework for decision-making.

• Bent (structural) – Bents are the fundamental building blocks that define the overall form and character of a structure. Unlike a specific Pratt truss, a bent is a cross-sectional template of structural members – like rafters, joists, and posts – that repeats along the length of the structure. Bents aren't limited to a single material; they can be constructed from timber, steel, or even concrete. They are the repeating structural ribs that give a building its skeleton.

• Bistable structure – A structure possessing two distinct stable equilibrium states.

• Brick – A ubiquitous building material, bricks are used to construct walls, pavements, and other elements in masonry construction. Traditionally made of clay, bricks are now also manufactured from clay-bearing soil, sand, and lime, or from concrete. They are typically joined with mortar, adhesives, or through interlocking designs. Bricks come in a vast array of classes, types, materials, and sizes, varying by region and historical period. They are broadly categorized as fired or non-fired.

• Brickwork – This is the art and practice of masonry created by a bricklayer using bricks and mortar. Rows of bricks, known as courses, are laid sequentially to build up structures like brick walls.

• Bridge – A structure engineered to span a physical obstacle, such as a body of water, valley, or road, allowing passage over it without impeding the flow beneath.

• Brittle – Describing a material that fractures with little or no deformation when subjected to stress.

• Buckling-restrained braced frame – A type of seismic force-resisting system designed to prevent buckling in its braces.

• Building engineering – A discipline focused on the structural integrity, systems, and construction of buildings.

• Building services engineering – This field deals with the design, installation, and maintenance of a building's essential systems, including heating, ventilation, air conditioning (HVAC), plumbing, and electrical systems.

• Bulk modulus – A measure of a substance's resistance to uniform compression.

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• Calcium aluminate cements – These are cements primarily composed of hydraulic calcium aluminates. Also known as aluminous cement, high-alumina cement, or "Ciment fondu" in French, they find use in specialized, smaller-scale applications.

• Camber beam – In construction, a camber beam is a piece of timber or steel that is deliberately shaped with an upward curve in the middle. This slight arch, ideally parabolic but often a circular segment, is used in platforms and other structures where long, strong beams are required, providing a subtle upward force to counteract expected downward deflection.

• Castellated beam – This is a type of beam fabrication technique. An I-beam is cut longitudinally along its web in a specific pattern, then reassembled to create a deeper web, leveraging the geometry of the cuts. It's a way to gain strength and depth efficiently.

• Cant – Also known as superelevation or banking, cant is the transverse slope of a railway track or road. It's particularly pronounced on curves, where the outer rail or edge is raised to allow vehicles to navigate the turn more safely and at higher speeds than would be possible on a flat surface.

• Cantilever – A rigid structural element, like a beam or plate, that is fixed at one end and extends outwards, unsupported at the other. It's a classic example of a structure resisting loads through bending.

• Cantlop Bridge – A specific, historical bridge structure.

• Carbon steel – An alloy of iron and carbon, characterized by its strength and hardness.

• Cast iron – An alloy of iron and carbon with a carbon content exceeding 2%. Its utility stems from its relatively low melting point, making it easier to cast into complex shapes.

• Casting – A manufacturing process where a liquid material is poured into a mold and allowed to solidify.

• Catenary – The curve formed by a flexible chain or cable hanging freely between two points under its own weight.

• Cavity wall – A wall constructed with an internal void between the inner and outer layers, improving thermal insulation and moisture resistance.

• Cement – A binder substance used in construction that sets, hardens, and adheres to other materials to bind them together.

• Cement render – A coating applied to walls, typically composed of cement, sand, and water, used for protection and decoration.

• Collar beam – A horizontal timber connecting two opposing rafters in a roof structure, typically located higher up than a tie beam.

• Color-tagged structure – A structure where components are marked with specific colors to indicate their properties or assembly sequence.

• Column – A vertical structural element designed to carry and transmit compressive loads from a superstructure to a foundation.

• Common rafter – A principal sloped structural member of a roof.

• Composite order – A classical architectural order that combines elements of the Ionic and Corinthian orders.

• Compressive strength – The ability of a material or structure to withstand an applied compressive load without failure.

• Computer-aided design – The use of computer systems to assist in the creation, modification, analysis, or optimization of a design.

• Computer-aided engineering – The use of computer software to simulate performance in order to improve product designs or assist in the resolution of engineering problems.

• Concrete – A composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement) that hardens over time, typically hydraulic cement.

• Concrete masonry unit – Precast concrete blocks used in masonry construction.

• Concrete pump – A machine used for transferring liquid concrete by pumping.

• Construction aggregate – See Aggregate (construction).

• Construction engineering – A specialized field within civil engineering focused on the planning, management, and execution of construction projects.

• Construction surveying – The surveying activities required to lay out structures and facilities on the ground.

• Corbel – A structural piece of stone, wood, or metal jutting from a wall to carry a superincumbent weight.

• Corinthian order – The most ornate of the classical Greek architectural orders, characterized by a capital decorated with acanthus leaves.

• Corrosion – The gradual destruction of materials by chemical and/or electrochemical reaction with their environment.

• Corrosion fatigue – Failure of a material under cyclic loading in a corrosive environment.

• Corrugated galvanised iron – Sheet metal with a specific profile, coated with zinc for corrosion protection, often used for roofing and cladding.

• Crane – A machine for lifting and moving heavy objects.

• Cross brace – A diagonal member used to stiffen a structure.

• Cross bracing – A system of diagonal members forming an 'X' or 'V' shape, used to provide rigidity.

• Curvilinear motion – Motion along a curved path.

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• Dam – A barrier constructed across a watercourse to obstruct, direct, or control the flow of water. Dams are vital for flood control, water supply for irrigation, human consumption, industrial use, aquaculture, and maintaining navigability.

• Damp proofing – Materials and techniques used to prevent moisture ingress into buildings.

• Damped vibration – Vibration that decreases in amplitude over time due to energy dissipation.

• Dead load – The weight of the structure itself and any permanent fixtures attached to it.

• Deep cement mixing – A ground improvement technique involving the mechanical mixing of cement with soil.

• Deep foundation – Foundations that transfer loads to deeper, more competent soil or rock strata.

• Deflection – The displacement or movement of a structural element from its original position under load.

• Deformation (engineering) – The change in shape or size of a component or structure under load.

• Deformation (mechanics) – A change in the form or size of a body.

• Density – The mass of a substance per unit volume.

• Deployable structure – Structures designed to be compacted for transport and then expanded into their operational configuration.

• Doric order – One of the three classical Greek architectural orders, characterized by its simple, sturdy columns and plain capital.

• Double tee – A concrete structural element consisting of two parallel stems connected by a thin slab.

• Dragon beam – A diagonal beam in a timber-framed roof that supports a hip rafter.

• Ductility – The ability of a material to deform under tensile stress without fracturing.

• Dumpy level – A surveying instrument used to establish or verify horizontal lines.

• Dynamic load testing – A method of testing the capacity of a foundation by applying rapid, transient loads.

• Dynamics – The branch of mechanics concerned with the motion of bodies under the action of forces.

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• Earthquake engineering – This specialized field of engineering focuses on designing and analyzing structures to withstand the forces imposed by earthquakes. The ultimate aim is to enhance the resilience and safety of buildings and infrastructure in seismically active regions.

• Earthquake-resistant structures – Structures specifically designed and constructed to minimize damage and maintain stability during seismic events.

• Earthworks (engineering) – The artificial movement of soil or rock to change the elevation or shape of the land.

• Edge jointing – The process of joining materials along their edges.

• Endurance time method – A computational method used in structural analysis to approximate the response of structures to dynamic loads.

• Engineering – The application of scientific principles to design, build, and maintain structures, machines, systems, materials, and processes.

• Engineering brick – A type of durable brick specifically designed for structural applications where resistance to frost, moisture, and chemicals is required.

• Engineering drawing – A standardized technical representation of a design, used to communicate design intent.

• Engineering economics – The application of economic principles to engineering decisions, evaluating costs and benefits.

• Engineering ethics – The moral principles and values that guide the conduct of engineers.

• Engineering physics – An interdisciplinary field that bridges physics and engineering, focusing on the theoretical underpinnings of engineering applications.

• Environmental load – Forces acting on a structure due to environmental factors like wind, snow, or temperature changes.

• Euler–Bernoulli beam equation – A fundamental equation in the theory of bending of beams, relating the applied load to the beam's deflection.

• Excavator – A heavy construction machine used for digging and moving earth.

• Expansion joint – A gap or space designed into structures to allow for thermal expansion and contraction.

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• Facade engineering – The design, construction, and performance of building envelopes, often referred to as facades.

• Falsework – Temporary structures used to support formwork or the structure itself during construction.

• Fascia – A flat architectural element, typically found at the edge of a roof.

• Feasibility study – An assessment of the practicality of a proposed project or system.

• Fibre-reinforced plastic – A composite material made from a polymer matrix reinforced with fibers.

• Finite element method – A numerical technique used to find approximate solutions to boundary value problems in engineering and physics.

• Fire protection engineering – The discipline concerned with preventing and mitigating fires.

• First fix – The initial stage of installation for building components, such as framing and roughing in utilities.

• Flange – A projecting rim or edge on a structure, used for strengthening or for attachment to another object.

• Flashing – A weather-resistant material used at junctions in building envelopes to prevent water ingress.

• Flexibility (engineering) – The inverse of stiffness; a measure of how much a structure or component deforms under load.

• Flitch beam – A composite beam made of timber and steel plates.

• Fluid – A substance exhibiting continuous deformation under shear stress.

• Fluid mechanics – The branch of physics that deals with the behavior of fluids.

• Fluid physics – The study of the physical properties of fluids.

• Fluid statics – The study of fluids at rest.

• Force – An interaction that, when unopposed, will change the motion of an object.

• Force lines – Lines representing the direction and magnitude of forces.

• Formwork – Temporary molds or structures used to contain and shape concrete until it hardens.

• Foundation – The part of a structure that transmits loads to the ground.

• Fracture toughness – A measure of a material's resistance to fracture when a crack is present.

• Framing – The structural skeleton of a building, typically made of wood or metal.

• Friction – A force resisting the relative motion of solid surfaces, fluid layers, and material elements.

• Furring – Thin strips of wood or metal used to create a level surface or provide spacing.

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• Gable – The triangular upper part of the end of a building, formed by the sloping roof.

• Grating – A framework of metal bars or open mesh, used for covering openings or supporting loads.

• Gravel – A loose aggregation of rock fragments, typically rounded by the action of water.

• Gravity-based structure – A structure whose stability relies on its own weight.

• Green roof – A roof partially or completely covered with vegetation and a growing medium, planted over a waterproofing membrane.

• Grout – A fluid cement mixture used to fill gaps or voids in construction.

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• H-beam – A structural steel section with an H-shaped cross-section, often used as beams or columns. Also known as a wide-flange beam.

• Half-timbering – A type of timber framing where the structural timbers are visible on the exterior of a building.

• Hammerbeam roof – A type of roof structure featuring projecting hammerbeams that support the main principals.

• Hardness – A measure of a material's resistance to scratching, indentation, or abrasion.

• Hardwood – Wood from deciduous trees, generally denser and stronger than softwood.

• Header – A structural member placed perpendicular to joists or rafters, often framing an opening.

• Henderson–Hasselbalch equation – An equation used in chemistry to calculate the pH of a buffer solution.

• High strength bolt – A bolt designed for use in structural connections, capable of withstanding high tensile and shear loads.

• High-tensile steel – Steel with a high yield strength, often used in structural applications where reduced material is desired.

• Hip roof – A roof with slopes on all four sides, meeting at the ridge and hips.

• Hod – A triangular carrier used by bricklayers to transport bricks and mortar.

• Hoist – A device used for lifting or lowering loads.

• Hollow structural section – Structural steel members with a hollow, typically square or rectangular, cross-section.

• Honeycomb structure – A structure that resembles a honeycomb, offering high strength-to-weight ratio.

• Hydraulic cement – Cement that sets and hardens by chemical reaction with water.

• Hydraulic engineering – The application of engineering principles to the control and use of water.

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• I-beam – A structural steel section with an I-shaped cross-section, commonly used as beams. Also known as a rolled steel joist or universal beam.

• Imposed load – Loads on a structure that are not permanent, such as those from people, furniture, or snow. Also known as live load.

• Infill wall – Non-load-bearing walls used to enclose spaces within a structural frame.

• Inflatable space structures – Structures designed to be deployed in space by inflating them.

• Influence line – A graphical representation used in structural analysis to show the variation of a reaction or internal force along a structure as a unit load moves across it.

• Insulating concrete form – Permanent or removable forms used to create insulated concrete walls.

• International Structural Engineering and Construction Society – A professional organization for structural engineers.

• International System of Units – The modern form of the metric system, used globally in science and engineering.

• Interval estimation – A range of values, derived from statistical data, that is likely to contain an unknown population parameter.

• Intrados – The inner curve or surface of an arch.

• Iron – A chemical element, a strong, magnetic, silvery-white metal, widely used in structural steel.

• Jack rafter – A rafter that forms part of a hip or valley in a roof.

• Jackscrew – A mechanical device that lifts heavy weights by turning a threaded screw.

• Jetty – A structure built out into a body of water to influence the current or tide, or to protect a harbor.

• Joinery – The craft of connecting pieces of wood, especially in furniture or buildings.

• Jointing – The process of filling the gaps between bricks with mortar.

• Joist – A horizontal structural member used in framing to support a floor or ceiling.

• Kee Klamp – A proprietary system of fittings used to create structures from tubing.

• Kentledge – Heavy material, such as iron pigs, used as ballast.

• Keystone – The wedge-shaped stone at the apex of a masonry arch, locking the other stones in place.

• King post – A vertical tension member in a king post truss.

• King post truss – A type of truss used in roofs and bridges, characterized by a central vertical king post.

• Lally column – A round, thin-walled structural steel column filled with concrete, used to support beams or timbers over long spans. It's a common, robust support element.

• Lightening holes – Openings in structural members to reduce weight without significantly compromising strength.

• Limit load (physics) – The maximum load a structure can sustain before undergoing significant deformation or failure.

• Limit state design – A design philosophy that considers the various limit states (e.g., ultimate strength, serviceability) that a structure may reach.

• Linear elasticity – A material behavior where stress is directly proportional to strain, and the material returns to its original shape upon unloading.

• Lintel – A horizontal structural element spanning an opening, such as a doorway or window.

• Live load – See Imposed load.

• Load bearing – The ability of a structural element to support applied loads.

• Load-bearing wall – A wall designed to carry structural loads from floors, roofs, or other walls above.

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• Mass balance – The principle that in a steady state, the rate of accumulation of mass within a system is zero.

• Mass density – The mass of a substance per unit volume.

• Material properties – The intrinsic characteristics of a material that determine its behavior under various conditions.

• Materials science – The interdisciplinary study of the properties and applications of materials.

• Metal alloy – See Alloy.

• Metallic bond – The type of chemical bond that holds metal atoms together in a metallic lattice.

• Middle-third rule – A design criterion for retaining walls, ensuring that the resultant force falls within the middle third of the base to avoid tension.

• Midhinge – A type of hinge used in structural analysis to represent a connection that allows rotation but no translation.

• Modified compression field theory – A theory used to predict the behavior of reinforced concrete members subjected to shear forces.

• Modulus of elasticity – A measure of a material's stiffness, also known as Young's modulus.

• Moment redistribution – The process of adjusting internal bending moments in a structure to achieve a more favorable distribution, often used in indeterminate structures.

• Monocoque – A structural technique where a structure's shell carries most of the stress, as opposed to using a load-bearing frame.

• Multidisciplinary design optimization – An approach to design that integrates expertise from multiple engineering disciplines to achieve optimal solutions.

• Multi-function structure – A structure designed to serve multiple purposes.

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• Non-hydraulic cement – Cement that does not harden in water, typically used for applications where moisture is absent.

• Offshore construction – The installation of structures and facilities in marine environments, primarily for resource extraction and energy production. It's often referred to as maritime engineering.

• Open web steel joist – Lightweight steel trusses used for supporting floors and roofs.

• Oriented strand board – A wood structural panel composed of cross-aligned strands of wood.

• Ortman key – A type of mechanical fastener.

• Overhang – A portion of a building's roof or floor that extends beyond the wall below.

• Panel building – A construction method using prefabricated wall panels.

• Permissible stress design – An older design method where stresses in structural members are kept below a predetermined allowable stress.

• Pile cap – A structural member that connects and distributes loads from columns or walls to a group of piles.

• Pile splice – A connection used to join two pile segments end-to-end.

• Plastic hinge – A localized region in a structural member where plastic deformation occurs under overload.

• Plasticity – The ability of a material to undergo permanent deformation without fracturing.

• Plate (structure) – A flat structural element, typically used in thin shells or as stiffeners.

• Ply (layer) – A single layer within a laminated material.

• Post (structural) – A vertical, load-bearing structural member, often used in timber framing.

• Pre-engineered building – A building whose components are fabricated off-site and then assembled on-site.

• Prestressed concrete – Concrete in which internal stresses are introduced to counteract the stresses caused by external loads, improving its tensile capacity.

• Prestressed structure – A structure that utilizes prestressed concrete or other materials.

• Progressive collapse – The failure of one structural element that triggers a cascading failure of other elements.

• Pyroshock – A transient mechanical shock generated by pyrotechnic devices.

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• Queen post – A pair of vertical tension members in a queen post truss.

• Rafter – One of the sloped structural members extending from the ridge or hip of a roof down to the wall plate or eave, supporting the roof deck. A pair is called a couple. In residential construction, rafters are typically wood. Exposed rafters are a common feature in various traditional roof styles.

• Rain gutter – A channel along the edge of a roof designed to collect and direct rainwater away from the building.

• Reinforced concrete – A composite material in which concrete's tensile strength is enhanced by embedding steel reinforcing bars or mesh.

• Reliability engineering – The discipline focused on ensuring that systems and components perform their intended functions without failure for a specified period.

• Rigid body – An idealized object that does not deform under stress.

• Rolled steel joist – See I-beam.

• Roof – The uppermost covering of a building, providing protection from the elements.

• Rubble trench foundation – A foundation system consisting of a trench filled with gravel or crushed stone.

• Sandwich panel – A composite panel consisting of two thin outer skins bonded to a thicker core material.

• Sandwich theory – A theoretical framework for analyzing the behavior of sandwich panels.

• Second fix – The later stage of building installation, involving finishing elements like trim, doors, and fixtures.

• Seismic analysis – The study of how structures respond to earthquake forces.

• Semi-monocoque – A structural design that combines features of monocoque and frame-and-skin construction.

• Settlement (structural) – The downward movement of a structure into the ground due to soil consolidation or deformation.

• Shallow foundation – Foundations that transfer loads to shallow soil layers near the surface.

• Shear strength – The ability of a material or soil to resist shear forces.

• Shear stress – The stress acting parallel to a surface.

• Shell – A curved structural element where the resistance to loads is primarily through membrane stresses.

• Shukhov Rotunda – A pioneering structure designed by Vladimir Shukhov, showcasing early applications of tensile structures.

• SI units – The modern, internationally recognized system of measurement, also known as the International System of Units.

• Siphon – A bent tube used to convey liquid over a barrier.

• Skyscraper – An extremely tall building.

• Softwood – Wood from coniferous trees, generally less dense than hardwood.

• Soil structure interaction – The study of how the behavior of a soil mass influences the response of a structure, and vice versa.

• Solid mechanics – The branch of mechanics concerned with the mechanical behavior of solids.

• Solid solution strengthening – A strengthening mechanism in alloys where solute atoms impede dislocation movement.

• Space frame – A three-dimensional truss structure composed of interconnected members.

• Span (engineering) – The distance between two supports for a beam, truss, or bridge.

• Specific weight – The weight of a substance per unit volume.

• Specified load – The load that a structure or component is designed to withstand.

• Spontaneous combustion – Ignition of a substance due to internal heat generation without an external ignition source.

• State of matter – The distinct forms in which matter can exist, such as solid, liquid, or gas.

• Static load testing – A method of testing the capacity of a foundation by applying gradually increasing static loads.

• Statical determinacy – A property of a structure where all internal forces and reactions can be determined using the equations of static equilibrium alone.

• Statics – The branch of mechanics concerned with bodies at rest or forces in equilibrium.

• Statnamic load test – A hybrid load testing method combining aspects of static and dynamic testing.

• Stave (wood) – A narrow, shaped plank used in constructing barrels or similar structures.

• Stewart platform – A six-degrees-of-freedom parallel manipulator.

• Stiffness – A measure of a structure's resistance to deformation under load.

• Storm drain – A system of pipes or channels used to carry away rainwater and surface runoff.

• Strain – The measure of deformation representing the displacement between particles in the body.

• Strain hardening – An increase in the strength and hardness of a material caused by plastic deformation.

• Street gutter – A channel along the edge of a street designed to carry away surface water.

• Strength of materials – The field of mechanics concerned with the behavior of solid materials under stress and strain.

• Stress – The internal force per unit area within a material.

• Stress–strain analysis – The study of how materials deform and withstand loads.

• Stress–strain curve – A graphical representation of a material's response to applied stress.

• Stressed skin – A structural system where the outer skin carries the primary loads.

• Structural analysis – The process of determining the effects of loads on a structure.

• Structural channel – A structural steel section with a C-shaped cross-section.

• Structural engineer – A professional engineer specializing in the design and analysis of structures.

• Structural engineering – The branch of civil engineering focused on the design and analysis of structures that support or resist loads.

• Structural engineering software – Computer programs used for structural analysis and design.

• Structural engineering theory – The fundamental principles and concepts underlying structural engineering practice.

• Structural fracture mechanics – The study of the initiation and propagation of cracks in structures.

• Structural health monitoring – The process of assessing the condition of a structure over time.

• Structural insulated panel – A composite building material consisting of an insulating foam core sandwiched between two structural facings.

• Structural integrity and failure – The study of how structures maintain their load-carrying capacity and the mechanisms by which they fail.

• Structural loads – Forces, deformations, or accelerations applied to structural components, causing stresses, strains, and displacements. Their assessment is crucial for safe design. Mechanical structures like aircraft and ships have their own specific load considerations. Engineers often refer to published regulations, contracts, or specifications, and adhere to accepted technical standards for acceptance testing and inspection.

• Structural material – Materials used in the construction of structures.

• Structural mechanics – The branch of mechanics that deals with the behavior of solid structures under load.

• Structural pipe fitting – Components used to connect pipes in structural applications.

• Structural robustness – The ability of a structure to withstand unforeseen events or abnormal loads without disproportionate collapse.

• Structural steel – Steel specifically manufactured for use in construction, characterized by its high strength and ductility.

• Structural steel design – The principles and practices involved in designing structures using steel.

• Structural system – The arrangement of structural elements that collectively resist loads.

• Strut channel – A C-shaped metal channel used in framing and support systems.

• Subbasement – A level below the main basement of a building.

• Subframe – A secondary frame that supports a primary structure or component.

• Sublimation – The transition of a substance directly from the solid to the gas state.

• Subsumption architecture – A hierarchical approach to robot control.

• Surface tension – The tendency of liquid surfaces to shrink into the minimum surface area possible.

• Superhard material – Materials that are extremely hard, typically ranking high on hardness scales.

• Surveying – The science and art of determining the terrestrial position of points and the distances and angles between them.

• Suspension bridge – A type of bridge where the deck is hung from vertical suspenders attached to large main cables.

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• T-beam – A structural element with a T-shaped cross-section, often used as a beam or in composite construction.

• Tainter gate – A type of adjustable gate used in dams and spillways.

• Technical standard – A document that establishes specifications, procedures, or criteria for products, processes, or services.

• Tensile force – A pulling force acting along the axis of a flexible medium.

• Tensile modulus – See Young's modulus.

• Tensile strength – The maximum stress a material can withstand while being stretched or pulled before breaking.

• Tensile structure – Structures that employ tension as their primary load-bearing mechanism, such as tensile membrane structures.

• Tensile testing – A method used to determine a material's tensile strength and ductility.

• Tension member – A structural element subjected to tensile forces.

• Thin-shell structure – A structure made from a thin, curved material that derives its strength from its shape.

• Tie (cavity wall) – A metal or plastic connector used to tie the inner and outer leaves of a cavity wall together.

• Timber framing – A construction method using heavy timber posts and beams to create the structural frame of a building.

• Topology optimization – A mathematical method that optimizes material layout within a given design space for a given set of loads and constraints.

• Torque – A twisting force that tends to cause rotation.

• Torsion – The twisting of an object due to an applied torque.

• Torsional vibration – Vibrations involving twisting or rotational motion.

• Toughness – The ability of a material to absorb energy and deform plastically before fracturing.

• Transient load – A temporary load applied to a structure, such as an impact or blast.

• Trimmer – A beam or joist used to frame an opening in a floor or roof.

• Tripod (foundation) – A foundation system consisting of three legs supporting a central column.

• Truss – A structural framework of interconnected members, typically forming triangles, used to span large distances.

• Truss connector plate – Metal plates used to join members in a wooden truss.

• Twin bridges – Two parallel bridges built side-by-side.

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• Ultimate tensile strength – The maximum tensile stress a material can withstand before fracturing.

• Universal beam – See I-beam.

• Universal column – A type of structural steel section with an H-shaped cross-section, used as columns.

• Valve – A device that regulates, directs, or controls the flow of a fluid.

• Vibration – An oscillatory motion of a body or system about an equilibrium point.

• Voussoir – A wedge-shaped masonry unit used in the construction of arches and vaults.

• W-beam – See I-beam.

• Weld access hole – A notch cut into a joint to allow for proper welding.

• Windpost – A vertical steel member used to support masonry walls against wind loads.

• Wood preservation – Treatment of wood to protect it from decay and insect attack.

• Woodworking joints – Methods of joining pieces of wood together.

• X-bracing – A type of bracing system where diagonal members form an 'X' shape, providing stability.

• Yield – The point at which a material begins to deform plastically under stress.

• Young's modulus – A measure of a material's stiffness or resistance to elastic deformation under tensile or compressive stress. Also known as the modulus of elasticity.

• Zero Defects – A quality management principle aiming to eliminate errors and defects.

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