Part 1 Memorials: Robert L'Hermite and his legacy, M.Fickelson the impact of Robert L'Hermite on the evolution of creep and shrinkage theory, Z.P.Bazant a tribute to Douglas McHenry, B.Bresler Hubert Rusch and his legacy, H.Hilsdorf. Part 2 State-of-the-art in mathematical modelling of creep and shrinkage in concrete: physical mechanisms and their mathematical description, J.F.Young et al material models for structural creep analysis, Z.P.Bazant et al creep and shrinkage analysis of structures, O.Buyukozturk et al finite element analysis of creep and shrinkage, C.A.Anderson et al probabilistic models, T.Tsubaki et al conclusions for structural analysis and for formulation of standard design recommendations. Part 3 Summaries of discussions from the symposium: physical mechanisms and their mathematical description, U.Schneider material models, P.E.Roelfstra structural analysis, V.Kristek finite element analysis, L.Cedolin uncertainty of creep and shrinkage predictions, S.G.Reid current research in material modelling, J.W.Dougill current research in structural analysis, B.Espion. Appendices: list of lectures and papers presented at the symposium list of participants.

Mathematical modeling of creep and shrinkage of concrete

The term Ultra-High Performance Concrete (UHPC) refers to a relatively new class of advanced cementitious composite materials whose mechanical and durability properties far surpass those of conventional concrete. This class of concrete has been demonstrated to facilitate solutions that address specific problems in the United States highway bridge infrastructure. Initial material development research on UHPC began more than two decades ago. First structural deployments began in the late 1990s. First field deployments in the U.S. highway transportation infrastructure began in 2006. For this study, UHPC-class materials are defined as cementitious-based composite materials with discontinuous fiber reinforcement that exhibit compressive strength above 21.7 ksi (150 MPa), pre- and post-cracking tensile strength above 0.72 ksi (5 MPa), and enhanced durability via a discontinuous pore structure. This report documents the state of the art with regard to the research, development, and deployment of UHPC components within the U.S. highway transportation infrastructure. More than 600 technical articles and reports covering research and applications using UHPC have been published in English in the last 20 years, with many more published in other languages. The report includes information about materials and production, mechanical properties, structural design and structural testing, durability and durability testing, and actual and potential applications. The report concludes with recommendations for the future direction for UHPC applications in the United States.

https://rosap.ntl.bts.gov/view/dot/26387/dot_26387_DS1.pdf

Ultra-High Performance Concrete: A State-of-the-Art Report for the Bridge Community

Finite element modeling of push-out tests for large stud shear connectors

Improved strength and durability of fly ash-amended concrete by microbial calcite precipitation

Flexural behaviour of pre-cast concrete sandwich composite panel – Experimental and theoretical investigations

This paper describes newly developed precast concrete sandwich panels. The panels use a new system of fiber reinforced plastic (FRP) connectors, developed at the University of Nebraska's Center for Infrastructure Research, for transferring shear forces from one concrete wythe to the other The use of FRP as the connector material increases the thermal efficiency of the panels compared to panels that contain steel or concrete connectors. The geometry and material properties of the new connector provide sufficient strength and stiffness for a significant transfer of shear between the two concrete wythes. The results of structural tests are analyzed and design recommendations are presented. Description of an accompanying thermal performance testing of these panels is also included. For full-scale specimens were tested in a vertical position. Two of the specimens contain the new FRP connectors, and two contain steel truss connectors. Measurements of load versus panel deflection and load versus connector stress are provided. The ultimate strength of the panels containing the new connector were found comparable to the strength expected of fully composite panels. The design of panels containing the proposed FRP connecting system can be undertaken ina manner similar to that composite panels. Ultimate strength of the panels can be computed assuming full composite action between the concrete wythes, it sufficient shear connectors are provided and the panels are not over-reinforced.

Full scale testing of precast concrete sandwich panels

The effect of confining entire members or parts of members, such as beams and columns, is known to strengthen the bond between the concrete and reinforcement. In this paper, the effect of confining the grout that surrounds isolated, single reinforcing bars on the bond strength between the bar and the grout is investigated. Grout-filled steel pipe splices with differnet parameters and geometrical design were prepared and loaded in axial tension until failure. The test specimens are described and the test results are presented, with discussion and analysis in light of existing theory. The experimental results show that a generic and inexpensive reinforcing bar splice for field connection of precast concrete members can be achieved using grout-filled standard steel pipe.

Grout-filled pipe splices for precast concrete construction

A new precast concrete sandwich panel system with a high thermal resistance and optimum structural performance has been developed. A hybrid truss provides the connector in this panel system - the diagonals are fiber-reinforced plastic bars and the chords are prestressed steel strands. Each connector consists of a fiber-reinforced plastic bar fabricated in a deformed spiral shape through which a pair of prestressing strands is threaded to provide anchorage in the concrete wythes. The developed shear connecting system is described together with its advantages. An experimental and analytical investigation of the connecting system was conducted. The experimental program included testing of small scale specimens by push-off loading, small scale panels by flexural loading. The analytical investigation included finite element modeling of the tested small scale specimens and comparisons with theory of elasticity solutions. Experimental and analytical results from finite element modeling and from theory of elasticity equations correlated well and showed that the developed panel system meets the objectives of the research and is expected to have a promising future.

A new structurally and thermally efficient precast sandwich panel system

Maher K. Tadros Cheryl W. Prewett Professor of Civil Engineering and Director Center for Infrastructure Research University of Nebraska Omaha, Nebraska Precast Concrete Sandwich Panels (PCSP), used as exterior walls in multi-unit residential, commercial, and warehouse buildings, are structurally and thermally efficient building elements, and they are in use worldwide; yet, there is very limited available information on the various design, production and construction philosophies. This paper presents the PCSP systems most widely used in North America and Europe as exterior walls for low rise commercial and warehouse buildings. The constituents of these panels are described, and some of the limited available research results are discussed. The theory of analysis for volume change effects is explained and numerical examples are given. A discussion of issues in need of further research is provided. Some widely used PCSP systems in North America and Europe are described in Appendix A, and the names of producers are included for further reference.

http://www.pci.org/uploadedFiles/Siteroot/Publications/PCI_Journal/1991/DOI_Articles/jl-91-november-december-8.pdf

State-of-the-Art of Precast Concrete Sandwich Panels

Shear studs used in composite steel bridge construction are typically 19.1 mm (34 in.) or 22.2 mm (78 in.) in diameter. This paper presents the development and implementation of the 31.8 mm (114in....

Maher K. Tadros

Papers

Full scale testing of precast concrete sandwich panels

Grout-filled pipe splices for precast concrete construction

A new structurally and thermally efficient precast sandwich panel system

State-of-the-Art of Precast Concrete Sandwich Panels

Large shear studs for composite action in steel bridge girders