Engineering Commons^™

Circular Reinforced Concrete Columns Damaged By Fire And Retrofitted With Cfrp And Steel Jacketing, Jia Xu

Dissertations - ALL

In recent decades, the post-fire behavior of reinforced concrete (RC) columns with normal and high-strength concrete has become an important research topic. Numerous studies have demonstrated that RC columns exhibit good fire resistance owing to the thermal properties of concrete. Therefore, reinforced concrete structures rarely collapse within a finite fire duration and can be successfully repaired. Along with the increasing number of skyscrapers, high-strength concrete (HSC) has played an equally important role as normal-strength concrete (NSC) in the industry. In this study, the thermal behavior of RC columns with NSC and HSC exposed to ISO 834 standard fire for various …

Characterization Of Vibration Effects On The Internal Structure And Strength Of Regular And High Strength Recycled Concrete, Jovanca Smith, Rekha Rampit, R. Parey

International Conference on Durability of Concrete Structures

There is a need for more in depth understanding of the consolidation effect of concrete on its durability, especially in tropical climates. During placement of fresh concrete in molds vibration is required to prevent quality problems such as honeycombs and desegregation. Nevertheless, precise monitoring of concrete vibration time has been avoided by construction professionals. This results in concrete durability reduction of appropriately designed concrete due to variation in aggregate settlement, air void content and change in water to cement ratio. In this study, the effects of vibration time on concrete strength, aggregate segregation, and physical properties were experimentally investigated on …

Hydrocarbon Pool Fire Performance Of Fiber Reinforced Polymer (Frp) Strengthened And Thermally Insulated Bridge Girders, Eyosias Solomon Beneberu

Civil Engineering Dissertations

Highway bridges encounter various extreme load hazards, such as earthquake, flood, blast, collision, wind and fire during their design lives. The effect of accidental, natural or man-made fire on bridges is one of the least investigated which may be due to the assumption that bridge fire has a low probability of occurrence. However, a bridge failure survey showed that fire had caused more bridge collapse in the USA than earthquakes. The main objective of the current research is to study concrete bridges in general, and fiber reinforced polymer (FRP) strengthened bridge girders in particular against fire hazard. The research is …

Normal-Strength And High-Strength Concrete Columns Under Cyclic Axial Load And Biaxial Moment, Mehdi Zarei

Dissertations

The technique of using Carbon Fiber Reinforced Polymer (CFRP) materials to repair and strengthen various concrete members has become popular in the structural retrofitting field as an effective way to enhance the strength and ductility of concrete members due to its superior mechanical properties. In this study a method was introduced to study the behavior of concrete columns with and without CFRP jackets under constant axial load and variable lateral load. The lateral load was applied monotonically and cyclically. To predict the behavior of concrete columns under monotonic and cyclic compressive loadings, a computer code was developed to produce the …

High Strength Steel Fiber Reinforced Flow-Able Or Scc Concrete With Variable Fiber By Volume Fractions For Thin Plate And Shell Structures, Abebe Berhe

UNLV Theses, Dissertations, Professional Papers, and Capstones

The purpose of this study is to incorporate discrete, short, mechanically deformed, small diameter steel fibers into high strength concrete with f'c > 70 MPa (10 ksi) in an attempt to reduce and partially eliminate the need for steel rebar in concrete construction. By introducing steel fibers to high strength concrete mixture, the overall tensile, compressive and shear strength of the mixture can be improved immensely thus, replacing portions or major parts of the longitudinal, temperature and shrinkage reinforcements. The reduction or elimination of longitudinal and transverse reinforcements in the construction of structural or non-structural members can result in savings in …

Effect Of Replacement Of Normal Weight Coarse Aggregate With Oil Palm Shell On Properties Of Concrete, Hilmi Mahmud

Hilmi Mahmud

Oil palm shell (OPS) is a waste from the agricultural sector and is available in large quantities in the tropical regions. This paper investigates the effect of the replacement of normal weight coarse aggregate by oil palm shells on the compressive strength, density, modulus of elasticity, workability and water absorption. The gradation of substitution was 0, 28, 55, 83 and 100 %. Two mixes based on high strength concrete (HSC) with binder (cement + silica fume) content of 550 and 600 kg/m 3 were used. The results show that the compressive strength, density and modulus of elasticity decrease and workability …

Production Of High Strength Concrete Incorporating An Agricultural Waste- Rice Husk Ash, Hilmi Mahmud

Hilmi Mahmud

Rice husk which is an agricultural waste, constitutes about one-fifth of the 500 million tonnes of rice produced annually worldwide. Normally, the residue is disposed off by burning at the mill sites and the resultant rice husk ash (RHA) is dumped on a waste land. This generates environmental, pollution and land dereliction problems. Under controlled burning and if sufficiently ground, the highly reactive ash that is produced can be used as a supplementary cementing material or in the production of high strength concrete (HSC). This paper shows that it is relatively easy to produce high strength Grade 80 concrete incorporating …

Application Of Ultra-High Performance Concrete To Bridge Girders, Maher K. Tadros Ph.D., P.E., George Morcous Ph.D.

Mid-America Transportation Center: Final Reports and Technical Briefs

Ultra-High Performance Concrete (UHPC) is a new class of concrete that has superior performance characteristics compared to conventional concrete. The enhanced strength and durability properties of UHPC are mainly due to optimized particle gradation that produces a very tightly packed mix, extremely low water to powder ratio, and use of steel fibers. The unique strength and durability properties of UHPC make it an attractive material for precast prestressed bridge girder construction. However, commercial UHPC mixes currently available in the US market cost about 10 times the cost of conventional concrete mixes, in addition to the need for special mixing and …

Uniaxial And Triaxial Behavior Of High Strength Concrete With And Without Steel Fibers, Xiaobin Lu

Dissertations

This study first presents an extensive experimental research program on the true uniaxial and triaxial compression behavior for both high strength concrete (HSC) and steel fiber reinforced high strength concrete (SFHSC). The experimental study mainly focuses on the octahedral shear stress strain relationship of those two types of concrete, which is adopted as the basis to develop a new incremental constitutive model. Emphasis is also put on the investigation of the variation of tangent Poisson's ratio under not only uniaxial but also triaxial stress conditions. The effect of cyclic loading on this parameter is also addressed.

According to this research, …