Stud shear connectors for composite beams

The published results of push tests were analysed statistically in order to determine the main parameters that affect the strength of stud shear connectors. The results of the statistical analysis were used to design a series of seventy-nine push tests. A finite element analysis program was developed which allowed for the interaction between the tensile and compressive failure of concrete and hence predicted the variation in the bearing strength of concrete prisms of varying size and with varying amounts of lateral restraint, when subjected to concentrated loads. A combination of-theoretical and empirical analyses was used to determine the load at which the stud broke, the strength of concrete prisms which were subjected to patch loads of varying size and eccentricity and hence the strength of concrete slabs, the effect of lateral forces and transverse reinforcement on the strength of the stud and the slab, the-strength of shear connections in which the reinforcement is looped around the stud and the load-slip curve for a stud shear connection

Derivation of normalized pressure impulse curves for flexural ultra high performance concrete slabs

In previous studies, a finite-difference procedure was developed to analyze the dynamic response of simply supported normal reinforced concrete (NRC) slabs under blast loads. Ultra high performance concrete (UHPC) is a relatively new material with high strength and high deformation capacity in comparison with conventional normal strength concrete. Therefore, the finite-difference procedure for analysis of conventional reinforced concrete members against blast loads needs to be significantly adapted and extended to accommodate UHPC. In this paper, an advanced moment-rotation analysis model, employed to simulate the behavior of the plastic hinge of an UHPC member, is incorporated into the finite-difference procedure for the dynamic response analysis of reinforced UHPC slabs under blast loads. The accuracy of the finite-difference analysis model that utilized the moment-rotation analysis technique was validated using results from blast tests conducted on UHPC slabs. The validated finite-difference model was then used to generate pressure impulse (PI) curves. Parametric studies were then conducted to investigate the effects of various sectional and member properties on PI curves. Based on the simulated results, two equations were derived that can be used to normalize a PI curve. Further numerical testing of the normalization equations for UHPC members was then undertaken. The generated normalized PI curve, accompanied by the derived normalization equations, can be used for the purposes of general UHPC blast design.Jonathon Dragos; Chengqing Wu; Matthew Haskett; and Deric Oehler

Experimental and Analytical Studies of Size Effects on Compressive Ductility Response of Ultra- High-Performance Fiber-Reinforced Concrete

Ultra-high-performance fiber-reinforced concrete (UHPFRC) has gained a great deal of increasing interest in structural engineering applications, particularly where high ductility, strength, and high impact resistance are of prime concern. This study focuses primarily on the size effects ductility characteristics of UHPFRC with varying fiber concentrations subjected to uniaxial compressive load. It shows how to process the data from compression cylinder tests to extract the size-dependent strain at peak stress to provide a generic size-dependent stress-strain analytical model. Furthermore, a numerical flexural segmental moment-rotation approach is applied to incorporate an analytical model to quantify apparently disparate UHPFRC member strength and ductility. Tests have shown that it is not the enhancement in the material concrete compressive strength but the phenomenal brittle ductility nature, observed as a result of increasing the slenderness of the specimen; in contrast, a substantial increase in ductility was achieved after crushing of concrete due to the addition of fibers. A size-dependent analytical approach has estimated good fit with the experimental and other published results. Finally, numerical simulation using a segmental approach at the ultimate limit state of rotation dealing with flexural ductility is significantly influenced by the increase in slenderness factor of the specimens and fiber concentrations

Flow and Strength Characteristics of Ultra-high Performance Fiber Reinforced Concrete: Influence of Fiber Type and Volume-fraction

Ultra-High Performance Fiber Reinforced Concrete (UHPFRC) has emerged all of the concrete in the construction industry because of its high strength, durability, serviceability and excellent ductility recently. Due to its high production cost, UHPFRC restricts its large-scale structural application. The conventional UHPFRC preparation consists of expensive materials such as specially graded sands which require complex mixing and curing process. The aim of this paper is to determine flow and strength properties of UHPFRC with the variation of fiber type and fiber volume-fraction. The UHPFRC composition was selected with four different fiber volume fractions (Vf = 0%, 1%, 2%, and 3%) of three different steel fibers at varying curing ages of 7, 28, 56 and 90 days within an identical mortar matrix. The paper provides an overview on the workability properties of UHPFRC followed by the presentation of compressive strength test results with different fibers and its volume-fraction with varying curing ages. The higher fiber volume-fraction resulted in a lower flow, and consequently an improvement of compressive strength observed up to 3% volume-fraction of fibers at 56 days curing. Finally, test results are compared and discussed with regard to the main variables: fiber volume-fraction, types of fiber; and curing ages of the specimens

Composite Steel and Concrete Structural Members Fundamentals Behaviour

xxxvii, 549hlm ; 25c

Mechanisms in composite structures / by Deric John Oehlers.

"December 2004"Includes bibliographical references.1 v. (various pagings) :Title page, contents and abstract only. The complete thesis in print form is available from the University Library.On understanding fundamental mechanisms that control the behaviour of composite structures.Thesis (D.E.)--University of Adelaide, School of Civil and Environmental Engineering, 200

Details of tests on steel and FRP plated continuous reinforced concrete beams

Sung-Moo Park and Deric J. Oehler

The effect os steel yielding on CFRP plated steel member by partial interaction theory

The reliability in strengthening concrete or steel structures using Carbon Fibre Reinforced Polymer (CFRP) depends on the success of the stress transfer between the two materials. This paper presented a simple numerical approach to simulate the stress transfer by applying partial interaction theory. The numerical approach uses a local bond–slip (τ–δ) model obtained from a previous experimental work. Pull tests were conducted on a dog–bone shaped steel specimens to initiate yielding of the steel. Results from the tests and published data compared with the numerical values show good correlations. These provide useful insights in the existence of full and partial interaction regions along the bonded length of the CFRP.Ibrisam Akbar, Deric Oehlers, Mohamed Ali Sadakkathull