Ultimate Bearing Strength of Post-tensioned Local Anchorage Zones in Lightweight Concrete

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dc.contributor.authorAxson, Daniel Peteren
dc.contributor.committeechairRoberts-Wollmann, Carin L.en
dc.contributor.committeememberCharney, Finley A.en
dc.contributor.committeememberCousins, Thomas E.en
dc.contributor.departmentCivil Engineeringen
dc.date.accessioned2014-03-14T20:40:25Zen
dc.date.adate2008-09-09en
dc.date.available2014-03-14T20:40:25Zen
dc.date.issued2008-05-21en
dc.date.rdate2009-09-09en
dc.date.sdate2008-06-23en
dc.description.abstractCurrently, NCHRP Report 356 has published an equation to estimate the ultimate strength of the local zone in normal weight concrete. The local zone is the area of concrete directly ahead of the bearing plate. The equation can be broken into two distinct parts: unconfined bearing strength of concrete enhanced by the A/A<sub>b</sub> ratio and the enhancement of strength due to the presence of confining. Research has shown that the strength enhancement of the A/Ab ratio and confining reinforcing is less in lightweight concrete than in normal weight concrete. To determine the strength of the local zone in lightweight concrete 30 reinforced prisms, 2 unreinforced prisms, and concrete cylinders were tested. The dimensions of the prisms were 8 in. x 8 in. x 16 in. and the cylinders were 4 in. x 8 in. cylinders. The simulated reinforcing in the prisms extended only through the top 8 in. of the prism and consisted of either ties or spirals with different spacing or pitch, respectively. To determine the effect of the A/A<sub>b</sub> ratio for each spacing or pitch arrangement of the reinforcing, one of two different size bearing plates were used. From the testing performed in this research and other research, it is apparent that the NCHRP equation is unconservative when estimating the ultimate strength of the local zone in lightweight concrete. By modifying both parts of the NCHRP equation it is possible to conservatively predict the ultimate strength of the local zone in lightweight concrete. Also investigated in this thesis are equations to predict the splitting cylinder strength and modulus of elasticity of lightweight concrete. For a sand-lightweight concrete, as defined by ACI 318-05 Building code and Commentary, the splitting tensile strength can be accurately predicted by multiplying the square root of the compressive strength by 5.7.en
dc.description.degreeMaster of Scienceen
dc.identifier.otheretd-06232008-215305en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-06232008-215305/en
dc.identifier.urihttp://hdl.handle.net/10919/33711en
dc.publisherVirginia Techen
dc.relation.haspartAxson.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectLightweight Concreteen
dc.subjectPost-tensioningen
dc.subjectModulus of Elasticityen
dc.subjectTensile Strengthen
dc.titleUltimate Bearing Strength of Post-tensioned Local Anchorage Zones in Lightweight Concreteen
dc.typeThesisen
thesis.degree.disciplineCivil Engineeringen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

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