Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 19 of 19 for “"concrete creep"”.
-
The nanogranular origin of concrete creep : a nanoindentation investigation of microstructure and fundamental properties of calcium-silicate-hydrates
… per capita consumption of one cubic meter, concrete is the most manufactured material on Earth. But concrete subject to sustained load creeps, like chewing gum, at a rate that deteriorates the durability and lifespan of concrete infrastructure. While it is generally agreed that concrete …
-
Continuity of bridges composed of simple-span precast prestressed concrete girders made continuous
… composed of simple-span, precast, prestressed concrete girders made continuous via cast-in-place decks and diaphragms are continuous only for live loads and superimposed dead loads. The continuity diaphragms often crack due to time dependent effects in the girders. These cracks not only impair …
-
Stress changes in reinforced concrete members due to creep
Under sustained loads plain concrete and concrete members experience the phenomenon known as creep. Creep varies in rate and magnitude depending upon the nature and magnitude of load and upon the physical characteristics of the concrete. From a review of the literature, creep coefficients are …
-
Micromechanical modeling of concrete at early age
… characterization of Portland cement concrete at early age (less than 28 days). Concrete’s viscoelastic properties change significantly at early age due to solidification of its matrix component. Bažant’s solidification theory models concrete as a material solidifying in time. This …
-
Analysis of time-dependent effects on segmental prestressed concrete curved box-girder bridges
… The analysis accounts for the effects of concrete creep and shrinkage, prestressed steel relaxation, differences in age between concrete segments, sequence of construction and changes in geometry and support conditions. Deviations in the positions of new segments due to the deformation of …
-
Compliance, relaxation and creep recovery of normal strength concrete.
… the long term serviceability of reinforced concrete structures requires an appropriate description of the mechanical properties of concrete. Among the long duration properties of concrete are shrinkage and creep of concrete. At relative humidities less than 96--99% concrete shrinks. For …
-
Unbonded Monostrands for Camber Adjustment
Prestressed concrete structural members camber upwards or downwards depending upon the location of application of prestress force. Identical members do not camber equally due to variability of the factors influencing it. Differential camber in the beams, if significant, results in excessively tall …
-
Investigation of Time-Dependent Deflection in Long Span, High Strength, Prestressed Concrete Bridge Beams
Accurate camber prediction in prestressed concrete bridge beams is important to all parties involved in bridge design and construction. Many current prestress loss prediction methods, necessary for proper camber calculation, were developed many years ago and are predicated on assumptions that may …
-
Prediction of Time-Dependent Stresses and Deflections in Prestressed, Concrete Girders: From Start of Fabrication to End of Service Life
… of the camber in precast, prestressed, concrete girders. Large differences in the camber between adjacent girders lead to significant construction difficulties that often have financial and/or legal ramifications. Many factors affect the time-dependent deflections of these girders …
-
Creep and Shrinkage Effects on Steel-Concrete Composite Beams
Predicting the long-term behavior of steel-concrete composite structures is a very complex systems problem, both because obtaining reliable information on material properties related to creep and shrinkage is not straightforward and because it is not easy to clearly determine the correlation …
-
Macro and nanocreep of self-consolidating concrete
Self-consolidating concrete (SCC) is a concrete that can flow under its own weight, easily filling forms with highly congested reinforcement. Due to its fresh properties, there has been growing interest in using SCC in precast and prestressed applications. These applications are known to be …
-
Creep and fracture of self-consolidating concrete incorporating fly ash
Self-consolidating concrete (SCC) is a relatively new type of concrete that has the ability to flow under its own weight such that it can pass through tightly spaced reinforcement and fill corners of molds without the use of mechanical vibration. Due to the favorable plastic properties of SCC, …
-
Time-dependent response of flat plate structures under high sustained load
Reinforced concrete (RC) structures may be exposed to high levels of sustained stresses resulting from errors in construction or design, abnormal loading, and material degradation. Although most RC structures are designed to withstand service level load with a large safety factor, errors may cause …
-
Investigation of Long-Term Prestress Losses in Pretensioned High Performance Concrete Girders
… losses is important in the design of prestressed concrete bridges. Over-predicting prestress losses results in an overly conservative design for service load stresses, and under-predicting prestress losses, can result in cracking at service loads. Creep and shrinkage produce the most significant …
-
Time dependent flexural analysis of reinforced concrete members
Concrete is one of the most widely used building materials in the construction industry in the world. Time dependent behaviour of concrete is the major concern for the structural engineers due to its significant effect in the long term serviceability and durability. Reinforced concrete (RC) members …
-
Numerically Modeling Steel Continuous Bridges for Early Age Concrete Deck Cracking
… relatively short bridges, 180 to 190 ft. long. Concrete cracking occurs when concrete tensile stresses exceed the concrete’s tensile strength. Therefore, early age bridge deck cracking is evaluated in this thesis be monitoring induced concrete tensile stresses and comparing these values with the …
-
Self-Compacting Concrete for Prestressed Bridge Girders
Self-consolidating concrete (SCC), which is different from conventional concrete especially in its fresh state, is a highly workable concrete that flows through congested reinforcement under its own weight alone, filling the formwork without segregation of its constituent materials with a void-free …
-
Illinois integral abutment bridges: behavior under extreme thermal loading and design recommendations
… that time-dependent behaviors, such as concrete shrinkage, may significantly influence maximum pile stresses for some IABs. Also, shrinkage may induce additional axial loads in the superstructure. Specifically, IABs using PPCI girders may exhibit unusually high contraction displacements …
-
Entwicklung eines Berechnungsmodells für das Langzeitverhalten von Stahlbeton und textilbewehrtem Beton bei überwiegender Biegebeanspruchung
Tragwerke aus Stahlbeton weisen infolge des Kriechens und Schwindens des Betons ein zeitveränderliches Materialverhalten auf. Die Folge sind Umlagerungen der im Querschnittsinneren wirkende Kräfte und im Zeitverlauf zunehmende Verformungen. Zur Beurteilung dieses Langzeitverhaltens sind geeignete …