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Connection Details for PBES

Appendix E: Glossary

The following terms are used in this document. The description of each term is written in the context of this document.

additivesSubstances (typically chemical) that are added to a grout mixture to counteract the natural tendency of grouts to shrink.
air release groutsA type of grout that does not rely on a chemical reaction to achieve expansion. The additive reacts with water to release air and cause expansion of the grout.
anchor rodsSteel rods that are used to transfer loads from the superstructure to the substructure. Often referred to as "anchor bolts", anchor rods differ in that they do not have a hexagonal head. Anchor rods are normally specified according to ASTM F1554.
approach slabsStructural slabs that span between the bridge abutments and the approach fill. They are used to span across the potential settlement of the approach roadway fills directly behind the abutments.
backwallA structural wall element that retains the backfill soils directly behind the beam ends on a bridge abutment.
barrierA structural wall element that is used to contain aberrant vehicles. They can be used on the bridge (parapet), or on the approach roadway.
batchingThe process of combining and mixing the materials to form concrete.
bearingA structural element that connects the bridge superstructure to the substructure, while allowing for movements such as thermal expansion and contraction.
bleed water (grout)Water that seeps out of the surface of a grout due to expansion of a grout in a confined or semi-confined area.
blockoutsVoids that are cast in prefabricated concrete elements that are used in connecting the elements in the field.
breastwallA wall that is typically non-structural that covers the beam ends at the corners of the bridge abutments. Sometimes referred to as "cheekwalls" by some states.
bridge deckA structural slab that spans between support elements (typically beams and girders) on a bridge. Bridge decks can be made of many materials, including reinforced concrete, steel, timber, fiber reinforced polymers, etc.
cable restrainersStructural elements that are used to restrain a bridge superstructure from excessive lateral movement during seismic events. The goal being to prevent the superstructure from falling off the substructure, which is a very common form of failure during seismic events.
camberA geometric adjustment of a bridge beam that is designed to compensate for the the vertical deflection of the beam when subjected to dead loads. Camber is typically built into steel beams during fabrication. Camber is in inherent side effect of prestressed girder construction.
carbon fiberA materials that is used in fiber reinforced polymer elements (FRP) to provide the structure performance. These fibers are oriented parallel to the direction of stress.
cast-in-place concreteConcrete that is cast on site (as opposed to cast in a fabrication plant).
cheekwallA wall that is typically non-structural that covers the beam ends at the corners of the bridge abutments. Sometimes referred to as "breastwalls" by some states.
cofferdamAn enclosure used to retain water in order to create a dry work environment. Typically used for bridge pier construction in rivers.
composite beam actionThe process of connecting the bridge deck to the beams or girders to form a combined structural element.
compositesThe combining of multiple structural materials to form a structural element.
compressive strengthThe value of uniaxial compressive stress reached when a material fails.
concreteA construction material that consists of cement (commonly portland cement), coarse aggregates (such as gravel limestone or granite), fine aggregates (such as sand), and water. Often other materials are added to improve the structural properties such as chemical admixtures and other cementitious materials (such as fly ash and slag cement).
concrete/steel hybrid decksA structural bridge deck system that combines structural steel elements with composite concrete to create a prefabricated deck system.
confinement steelReinforcing steel used to contain the concrete core of a column when subjected to plastic deformations brought on by seismic loading.
consistencyThe state of a mixture of materials where the formulation is of uniform quality.
constructabilityThe extent to which a design of a structure provides for ease of construction yet meets the overall strength requirements.
construction jointsJoints in structures that are used to facilitate the construction of a portion of the structure. Construction joints typically have reinforcing steel passing from one side of the joint to the other.
construction stagesA process of building a bridge in segments in order to maintain traffic during construction.
continuity connectionA connection used to connect two longitudinal bridge element (beams) to form a continuous bridge system. Typically these connections are only designed to resist live load.
continuous spansA structural system where the beams span across more than two supports without joints.
contraction jointsJoints in structures that are used to allow the concrete elements to shrink without causing excessive cracking. Contraction joints typically do not have reinforcing steel passing from one side of the joint to the other.
conventional constructionConstruction methods that do not include large scale prefabrication.
cover concreteA layer of concrete placed around reinforcing steel to prevent the corrosive attack from water and other elements.
critical pathThe portion of the sequence of construction activities which represents the longest overall duration. This in turn determines the shortest time possible to complete a project.
cross frameA transverse structural element connecting adjacent longitudinal flexural components used to transfer and distribute vertical and lateral loads and to provide stability during construction. Sometimes synonymous with the term "diaphragm".
crownThe apex of the roadway cross slope.
curing compoundsChemical compounds that are used to prevent the rapid evaporation of water from concrete during curing.
curbA structural element that is constructed at the edge of bridge deck that is used to contain rain water runoff. Curbs are often combined with structural railings to retain vehicles.
debondingThe process of disconnecting prestressing strand from the surrounding concrete in a prestressed concrete element. This is done to control stresses in prestressed elements (typically at the at the ends).
deckThe structural portion of a bridge that is directly beneath the wheels of passing vehicles.
dewateringThe process of removing water from an excavation that is below the water table.
diaphragmA transverse structural element connecting adjacent longitudinal flexural components used to transfer and distribute vertical and lateral loads and to provide stability during construction. Sometimes synonymous with the term "cross frame".
differential camberA variation on the camber of two adjacent beams. See "camber".
dimensional growthThe phenomenon that results in the change in overall structure width or length when multiple elements are butted together. This is brought on by a build up of element side variations or tolerances that are a result of the fabrication process.
distribution directionA direction that is normally parallel to the supporting members and is perpendicular to the direction of beam action in reinforced concrete slabs that are designed for one-way slab action.
drilled shaftsA deep foundation unit, wholly or partly embedded in the ground, constructed by placing fresh concrete in a drilled hole with or without steel reinforcement. Drilled shafts derive their capacity from the surrounding soil and/or from the soil or rock strata below its tip. Drilled shafts are also commonly referred to as caissons, drilled caissons, bored piles, or drilled piers.
dry pack groutA form of grout that has very stiff consistency that is placed by packing the material into voids by hand and hand tools.
effective prestressThe stress or force remaining in the prestressing steel after all losses have occurred.
elastomeric bearing padsA type of structural bearing that is comprised of neoprene or natural rubber. Sometimes combined with internal steel plates, fiberglass sheets, or cotton duck sheets.
emulation designA design method where a prefabricated connection is designed and detailed to act as (or emulate) a conventional concrete construction joint.
epoxy adhesive anchoring systemsA method of embedding reinforcing steel or steel rods into hardened concrete to form a structural connection. The process involves a drilled hole and a chemical adhesive.
epoxy groutsGrout materials with chemical adhesives used in place of cementitious materials.
ettringite expansive groutEttringite is crystal that forms as a result of the by product of reactive chemicals that can be interground into the cement in expansive grouts to produce non-shrink grout.
exodermic bridge deckA bridge deck system that is composed of a steel grid deck combined with a top layer of concrete to form a composite system. This system differs from filled grid decks in that the concrete is placed above the top of the grid to maximize the composite action between the steel and the concrete.
expansion jointsJoints in structures that are used to allow the concrete elements to expand and contract with temperature variation without causing excessive cracking. Expansion joints are similar to contraction joints except they are normally wider and often include a compressible material to allow for thermal expansion. They also do not have reinforcing steel passing from one side of the joint to the other.
fiber reinforced polymers (FRP)A structural matrix of materials used to produce a structural element. FRP is commonly made reinforcing fibers that are combined with polyester, epoxy or nylon, which bind and protect the fibers from damage, and transfers the stresses between fibers. FRPs are typically organized in a laminate structure, such that each lamina (or flat layer) contains an arrangement of unidirectional fibers or woven fiber fabrics embedded within a thin layer of light polymer matrix material. The fibers, typically composed of carbon or glass, provide the strength and stiffness.
filled steel gridsA bridge deck system that is composed of a steel grid deck combined that is either fully or partially filled with concrete.
flowable fillA material used to rapidly fill a void in embankment backfills or under structures without compaction. It normally has high flow characteristics. It is commonly made up of sand, water and a minor amount of cement.
flying wingwallsWalls used to retain embankment soils at the corners of abutments that are cantilevered from the end or rear of the abutment as opposed to being supported on a footing.
foam block fillA material used to rapidly fill embankments where low unit weight materials are desired. This is often used over highly compressible soils such as clays.
full-depth precast concrete deck slabsA bridge deck system that is composed of reinforced concrete elements that when placed, make up the full structural deck system.
gantry craneA crane type that is characterized by two or more legs supporting an overhead beam with a traveling trolley hoist.
gas generating groutA type of non-shrink grout that expands due to the production of gas during the curing process. The gas is generated by adding reactive materials to the mix (often aluminum) to produce the gas.
girder-floorbeam bridgesA bridge framing system that is composed of main girders that run parallel to the roadway combined with transverse floorbeams that support the deck. Often the system includes stringer beams that run between floorbeams (parallel to the roadway).
glue laminated woodA structural framing material that consists of multiple layers of dimensional lumber glued together to form a large timber element.
groutA material (often cementitious or epoxy) that is used to fill voids between elements.
grouted reinforcing splice couplersA proprietary product used to join precast concrete elements by connecting reinforcing steel bars at the ends of the elements. They consist of a steel casting sleeve that is filled with grout. The reinforcing bars are inserted into the ends of the casting and developed by the interaction of the grout with the sleeve.
haunchThe material between the top of a beam element and the bottom of the bridge deck that gaps the space between the two elements (also referred to as the  web gap  in some states).
high early strength concreteA concrete mixture that gains strength rapidly in order to accelerate construction.
integral abutmentA bridge abutment type that is made integral with the bridge superstructure through a combined shear and moment connection. They are often constructed with a single row of piles that allow for thermal movement and girder rotation. Soil forces behind the abutments are resisted through the strut action of the superstructure.
integral abutment connectionThe connection between the superstructure and the integral abutment substructure that can resist both shear and moment.
integral pier connectionThe connection between the superstructure and the pier substructure elements that can resist both shear and moment.
keeper assembliesDevices that are placed on top of substructures to prevent lateral movement of the bridge superstructure. They are often used to resist lateral seismic forces. They can be constructed with structural steel or reinforced concrete.
leveling boltsBolt assemblies embedded in prefabricated elements that are used to make grade adjustments in the file during construction.
match castingA process of joining two precast concrete elements with high precision. This is done by casting one element against the adjoining element in the fabrication yard, separating them, and then re-joining them in the field. The field connection is normally made with thin epoxy adhesives combined with post-tensioning
mechanical splicesDevices used to connect reinforcing steel through mechanical means. Examples of these systems include grouted sleeves, wedge assemblies, and threaded bar ends.
mechanically stabilized earth (MSE) retaining wallsA soil-retaining system, employing either strip or grid-type, metallic, or polymeric tensile reinforcements in the soil mass, and a facing element that is either vertical or nearly vertical. In this system, the soil mass is engaged by the strips to become a gravity type retaining wall.
mild reinforcementSteel bars or grids within concrete elements that are used to resist tension stresses. Mild reinforcement normally consists of deformed steel bars or welded wire fabric.
modular block retaining wallsA soil-retaining system employing interlocking soil-filled timber, reinforced concrete, or steel modules or bins to resist earth pressures by acting as gravity retaining walls.
near site fabricationA process of constructing prefabricated elements near the bridge construction site in order to minimize problems with shipping of large components.
non-shrink cementitious groutA structural grout used for filling voids between elements that is formulated with cement, fine aggregates and admixtures. The admixtures are used to provide expansive properties of the material during curing. This expansion counteracts the natural tendency of cement grouts to shrink during curing.
one-way slabA reinforced concrete slab system that primarily spans between two parallel support members. In this system, the majority of the reinforcing runs perpendicular to the support members.
open grid decksA bridge deck system that is composed of an open steel grid spanning between supporting members.
parapetA structural element that is constructed at the edge of bridge deck that is used to contain aberrant vehicles.
partial-depth precast concrete deck panelsA bridge deck system that consists of relatively thin precast concrete panels that span between supporting members that are made composite with a thin layer of sitecast reinforced concrete. The precast panel makes up the bottom portion of the structural slab. The site cast concrete makes up the remainder of the structural slab.
pier boxA prefabricated system that includes a precast concrete box that is placed over driven piles or drilled shafts. The box becomes the form to contain site cast reinforced concrete. Often pier boxes are used in water applications to form a cofferdam for the footing concrete.
pier capA structural beam spanning between pier columns.
pier columnThe vertical structural element in a bridge pier
pile bent pierA bridge pier without a footing that is comprised of driven piles or drilled shafts supporting a pier cap.
pile cap footingA footing that is supported by driven piles or drilled shafts.
plastic hingeA method of dissipating lateral seismic forces by allowing portions of reinforced concrete pier columns to bend beyond the yield point. Stability of the structure is maintained by providing adequate confinement reinforcement.
post-tensioning ductsA form device used to provide a path for post-tensioning tendons or bars in hardened concrete
post-tensioning (PT)A method of prestressing in which the tendons (strands or bars) are tensioned after the concrete has reached a specified strength.
precast concreteConcrete elements that are cast in a location other than their final position on the bridge.
prefabricationThe process of building bridge elements prior to on-site construction in order to accelerate the construction of the bridge.
prestressed concreteConcrete components in which force is introduced into the element during fabrication to produce internal stresses that are normally opposite of the anticipated stresses in the completed structure. Prestressing can be accomplished with pretensioning or post-tensioning.
pretensioningA method of prestressing in which strands are tensioned before the concrete is placed, and released after the concrete has hardened to a specified strength.
quality assurance and quality control (QA/QC)The process of inspection and control during fabrication to ensure that the specified quality is achieved.
reflective crackingA crack that can form in site cast concrete that is placed over a joint between two elements below the pour.
reinforced closure poursA method of connecting two prefabricated elements by casting a segment of reinforced concrete between two elements. The connection is often made using lap splices or mechanical reinforcing connectors.
reinforced concreteConcrete elements with reinforcing steel cast into the concrete to form a structural element. The steel is normally used to resist tension stresses in the element.
reinforcing steelSteel placed in concrete elements (either be mild reinforcement of prestressing steel).
saturated surface dry (SSD) conditionA condition that is normally specified for concrete surfaces that are to be grouted. Saturated Surface Dry describes the condition of the concrete surface in which the pores are filled with water; however no excess water is on the surface. This condition minimizes the absorption of water from the grout into the surrounding concrete.
segregationA condition where the distribution of course or fine aggregates in the concrete or grout mix become nonuniform.
self-propelled modular transporter (SPMT)A high capacity transport trailer that can lift and move prefabricated elements with a high degree of precision and maneuverability.
shear keyA shaped joint between two prefabricated elements that can resist shear through the geometric configuration of the joint.
shear studsHeaded steel rods that are welded to elements to provide composite action between two bridge elements. Typically used between beams and the deck slab.
sheetingA structural system used to retain earth and water and allow for excavation during the construction of a bridge substructure.
shims packFlat plates placed between two prefabricated elements used to provide a specified separation. Shims are also used to make vertical grade adjustments. Shims are typically made of steel or polymer sheets.
shrinkage (grout)A property of cementitious concretes and grouts that occurs during curing where the material reduces in size.
spandrel wallA wall that is constructed on the sides of earth filled arch structures that are used to retain the fill soils.
spiral reinforcementTransverse reinforcement used in reinforced concrete columns to resist shear. Spirals are also used for confinement of the concrete core as a plastic hinge forms.
steel stay-in-place formsCorrugated steel sheeting that is used to support the wet concrete in a bridge deck during construction, and left in place in the permanent structure.
strength directionA direction that is normally perpendicular to the supporting members and is parallel to the direction of beam action in reinforced concrete slabs that are designed for one-way slab action.
stress laminated timber deck bridgesA timber bridge deck that is comprised of multiple layers of dimension lumber placed on edge and connected with transverse prestressing. Shear transfer between the laminations is accomplished through friction.
stringersThere are two common uses for this term.
  1. Longitudinal steel beams on short span multi-beam bridges.
  2. Secondary framing members on floor beam type bridges that span from floor beam to floor beam.
stub abutmentsA short cantilever type abutment that is constructed near the top of the approach embankment.
substructureThe portion of the bridge that is below the beam and/or deck elements. It typically includes piers, abutments, and walls.
superstructureThe portion of the bridge that is above substructure. It typically includes beams, girders, trusses, and the bridge deck.
surface preparation (grout)The process of preparing a concrete surface for grouting by cleaning or intentionally roughening the surface. This is done to improve the adhesion of the grout to the concrete. It typically includes sand blasting, water blasting, or hand tool cleaning.
sweepThe lateral curvature of a prefabricated element caused by fabrication form irregularities and/or internal stresses.
test pours and test mockupsA method of quality control whereas a contractor will build a model of a portion of the bridge structure that includes a void that requires grout placement. These are used to demonstrate proper grout placement in complex voids.
timber deck panelsPrefabricated timber panels that are made with glue laminated lumber.
toleranceSpecified allowable dimensional variations in prefabricated elements. The variations are a result of irregularities in formwork and minor deviations in measurements during fabrication.
transverse tiesReinforcement used in reinforced concrete columns to resist shear. Ties, if properly detailed, can also used for confinement of the concrete core as a plastic hinge forms.
tremie concrete pourConcrete that is placed underwater and within a cofferdam to resist the vertical pore pressure of the water below a footing during construction.
user costsCosts that incurred by users of a highway network when they are delayed due to construction activities.
variable web gapSee "Haunch"
water contentThe specified amount of water in a concrete or grout mix.
wearing surfaceThe top portion of the bridge deck that is directly below the vehicle tires. Often wearing surfaces are designed to be sacrificial and replaceable.
wet curingCuring is the process of retaining sufficient moisture (water) in freshly placed grout/concrete to complete the hydration reaction which occurs when water is introduced to Portland cement. Wet curing leaves the freshly placed grout/concrete in an environment of 100 percent humidity
working timeThe amount of time that a concrete or gout mix remains in a liquid or plastic state so it can be placed and consolidated.
yield strengthThe stress at which an elastic material begins to deform in a plastic manner. Prior to yield, the material will deform elastically and will return to its original shape when the applied stress is removed. If loaded beyond yield and then unloaded, the material will not return to its original shape.
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Updated: 06/27/2017
Federal Highway Administration | 1200 New Jersey Avenue, SE | Washington, DC 20590 | 202-366-4000