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BRIDGE TERMS - L |
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L-abutment |
L-abutment - a cantilever abutment with the stem flush with the toe of the footing, forming an L in cross section laced column - a column built up from several members with lacing lacing - small flat plates used to connect individual sections of built up members; see LATTICE lagging - forms used to produce curved surfaces; see FORMS lamellar tear - incipient cracking between the layers of the base material (steel) laminated timber - small timber planks glued together to form a larger member lap joint - a joint between two members in which the end of one member overlaps the end of the other lateral bracing - the bracing assemblage engaging a member perpendicular to the plane of the member; intended to resist lateral movement and deformation; also provides resistance against raking of primary parallel elements in truss bridges and girder bridges; see BRACING lattice - a crisscross assemblage of diagonal bars, channels, or angles on a truss; also known as latticing, lacing lattice truss - in general, a truss having its web members inclined but more commonly the term is applied to a truss having two or more web systems composed entirely of diagonal members at any interval and crossing each other without reference to vertical members leaching - the action of removing substances from a material by passing water through it lead line - a weighted cord incrementally marked, used to determine the depth of a body of water; also known as sounding line leaf - the movable portion of a bascule bridge which forms the span of the structure lenticular truss - a truss having parabolic top and bottom chords curved in opposite directions with their ends meeting at a common joint; also known as a fish belly truss levee - an embankment built to prevent flooding of low-lying land light-weight concrete - no-fines concrete, aerated concrete, or concrete made of lightweight aggregate link - a hanger plate in a pin and hanger assembly whose shape is similar to an eyebar, i.e., the head (at the pinhole) is wider than the shank link and roller - an adjustable device or assemblage consisting of a hinged strut-like link fitted with a roller at its bottom end, supported upon a shoe plate or pedestal and operated by a thrust strut serving to force it into a vertical position and to withdraw it therefrom; when installed at each outermost end of the girders or the trusses of a swing span their major function is to lift them to an extent that their camber or droop will be removed and the arms rendered free to act as simple spans; when the links are withdrawn to an inclined position fixed by the operating mechanism the span is free to be moved to an open position live load - a dynamic load such as vehicular traffic that is applied to a structure suddenly; also accompanied by vibration or movement affecting its intensity load - the weight carried by a structure load indicating bolt - a bolt whose head carries small projections on its underside, which compress as the bolt is tightened; gives a direct indication of the bolt tension that has been achieved load rating - an office exercise to determine the ability of a bridge to carry load based on the conditions reported by an inspector longitudinal bracing - bracing that runs lengthwise with a bridge and provides resistance against longitudinal movement and deformation of transverse members loss of prestress - loss of prestressing force due to shrinkage and creep of the concrete or creep of the prestressing tendon and loss of bond low-carbon steel - steel with 0.04 to 0.25% dissolved carbon; also called mild steel lower chord - the bottom horizontal member of a truss |
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