6926475944

st co ner et e. Crack propege-

Key Word*. Bridges, Paneli, Pri tk>n. Moving loads

Time and aconomkc factort favor compotite precast deck bridges ovar conventionel cast-in-piace decki. Altbough both systems hava baan uead succetsfully for many yaars, the precast system exhfck« mora ragular cracking patterns than tha cast-in-płace system. Based on field measurements of deflectton patterns, both under static and dynamie moving vehicia loads, laboratory tasting on ^>«cinneni subjected to cycłk loads, ampla cores obtained from the structure, and fintte element model ing. tha causes of crack i ng have baan idantifiad. Differentiel craap and dtrinkaga and. where applkable. tha lack of positłve baaring of tha precast penels ovar tha girdars all contribute In different proportions to tha crack ing. Prelkninary avaloation of the effects of crack-ing, suggestions on how to improva tha performance of the deck system, and description of continuing work on laboratory tasting is presantad. A rapid automatic data acquisition system is deserad for obtaining field and iaboratory data.

84-1581

Bridge Pile Dunage upon Ve«el Impact

K.N. Derucher

Stevens Inst. of Tech., Hoboken, NJ 07030, Com-puters Struć., 18 (5), pp 931-935 (1984) 8 figs, 4 refs

Ph.D. Thesis, Lehigh Univ., 268 pp (1983) DA8329476

Key Words: Bridges, Structural members, Joints (junctions), Rivated joints, Fatigue Hfe

The fatigue reiistance of old rivated truss bridge mambars and joints is investigeted. Clamping forces in rivats and friction between interfacing płatas are eon lider ad not de-pendable and ignored. The componerrti of riveted details are subsequently resolved into piane stress platas. Emphasis is placed on developing an analytical procedurę for asti-mating fatigue crack propagation Hfe of riveted truss details. The analysis of member stresses is conducted by finłte element modeling of a bridge spen as a thrae dimensionel spece frame. Redistribution of stresses in truss bridge members when one develops a crack is examined by assuming the reduction of cross section occurs throughout the member length. By using singular isoparametric piane stress elements, the fracture mechanics stress intensity factor for cracks emanating from rivet holes is evaluated through a virtual crack extension method. Two types of details are studied: riveted built-up truss members with no transfer of load between component plates and riveted truu joints where rivets transfer loads by bearing.

BUILDINGS

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Bridge

Key Words: Pila structures, Bridges, Ships, Collision research (ships)

Many pierś of bridges that span navigable waters are inerea* ingly subjected to veseel impact. Many of these bridge pierś ara co ner eta and ara constructed such that the piling system and tha bridga pier ara ona. Depending upon the size and tha materiał of tha pile and upon vessel impact there may be a failura wrthin tha pila itself or at the pila-piar intersection. If tha impact is great enough, tha failura or fracture may ba a complata one, and the pier moves horlzontałly and/or yertkalfy. Thus, failure of the bridga may result while the pier is still intact. A naw bridga may be built or rehabilrtated using tha exłsting pier whkh may now be inadequate. In many casas tha amount of piling failure is dłff icult to assess. A procedura hat baan devek>ped to determine the amount of pier movement (failura of tha pilas) that might occur. The procedura usas a modłfication of two existing Computer programs (a ket ara > pila program and a pile group program).

84-1582

Fitigae Reństance of RWeted Steel Truss Members and Joints

Chun Kyung Seong

84-1583

The Effect of the Angłe of Incidence on Residential Acoustical Insulation

F.L. Hall and N. Bechrakis

McMaster Univ.. Hamilton, Ontario. Canada L8S 4L7, Noise Control Engrg. J.. 22 (2), pp 42-47 (Mar/Apr 1984) 1 table, 15 refs

Key Words: Buiłdings. Noise reduction, Airports

The effectiveness of acoustical insulation in residential housing near airports may vary during an aireraft flyover, depending on tha relatłva locetion of the flight pathsand tha housing, because the angle of incidence of sound wavas effects transmission loss. Altarnatively, the number of reflected paths in normal residential araas may ba so great es to ovarride any such effect. This papar tests these two possibilłtias using field data collected for 20 rooms. Tha results show that the meen value of tha decrease in insulation during an aireraft flyover is ciosa to 5 d8. For thosa casas where the aireraft passat directly over tha housa, the lowast insulation valuet occur at the time when the outdoor sound due to tha aireraft isat its highest level.

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