Working Drawing Manual

Seismic Retrofitting Guidelines for Complex Steel Truss Highway Bridges

This manual, entitled Seismic Retrofitting Guidelines for Complex Steel Truss Highway Bridges (referred to as Guidelines in this document), collects and summarizes the state-of-the-practice, up to 2005, for retrofitting steel truss bridges on the highway system within the United States. These Guidelines are based on and are supplementary to the Seismic Retrofitting Manual for Highway Structures Part 1: Bridges (referred to in these Guidelines as the Bridge Retrofitting Manual), developed by the Multidisciplinary Center for Earthquake Engineering Research (MCEER), to be published by the Federal Highway Administration (FHWA) in 2006. The Bridge Retrofitting Manual divides ordinary highway bridges into two classifications, “essential” and “standard,” by their expected performance after a seismic event. Essential bridges are all bridges that are expected to function after a seismic event by continuing to carry traffic. Standard bridges are all other ordinary highway bridges, which may sustain minor to serious damage after a seismic event (but preserve life safety) and may need extensive repair or replacement. These Guidelines also define two classifications of highway steel trusses by their truss configurations: “seismically standard” trusses, which are “ordinary highway bridge” trusses; “seismically complex” trusses, which are the “unusual” types of highway steel trusses; and “long-span” highway steel trusses. All highway truss bridges that meet the classification of “essential bridges” in the Bridge Retrofitting Manual are automatically classified as “seismically complex” trusses in these Guidelines. As in the Bridge Retrofitting Manual, a performance-based seismic retrofit philosophy is used in these Guidelines with performance criteria specified for two earthquake ground motions: a lower level earthquake with a mean return period of 100 years, and an upper level earthquake with a mean return period of 1,000 years. For the “seismically standard truss” classification, a higher performance requirement is specified for the lower level earthquake than for the upper level earthquake. For the “seismically complex truss” classification, a higher performance requirement is specified for both lower level and upper level earthquakes, because seismically complex trusses have special structural configurations that behave under seismic excitation in a complex manner; thus they require a higher standard of seismic retrofit. These Guidelines are written primarily for practicing bridge design engineers who have some familiarity with the seismic retrofitting design of ordinary steel and concrete girder bridges. Experience in the applications of more advanced design techniques such as nonlinear analysis, soil-foundation-structure interaction, and experience with bridge construction methods are helpful in applying these Guidelines. U.S. customary units are used rather than SI units because they were used in the construction of most of the truss bridges that will require seismic retrofitting. Theses Guidelines comprise seven chapters on the technical application of the seismic retrofitting of steel truss highway bridges:
1 Introduction
2 Retrofitting Philosophy and Process
3 Screening and Prioritization
4 Structural Analysis
5 Design Parameters
6 Evaluation of Members, Connections and Subsystems
7 Retrofit Measures, Approach and Strategy
Three additional chapers provide supporting information:
8 Case Studies
9 Glossary
10 References and Bibliography

Frost Resistance of Building Materials, Proceedings of the 3'd Nordic Research Seminar in Lund

This report contains papers presented at a Research Seminar , or rather "workshop", organised by our Department. It is the third in a series. The previous seminars were held in 1993 and 19961• The seminar is "Nordic", by which is meant that the speakers came from the Scandinavian countries -Demnark, Norway, Sweden- and Finland. Certainly there are other Nordic countries in which frost is a real problem, but this time there were no participants from these countries. Most participants were invited personally and asked to give presentations. The seminar language was English making it possible also for participants from outside Scandinavia to take part. This time same German guest research students took part as "observers" and as contributors to the discussions.
The papers cover many aspects of frost damage. Some papers discuss the very important problem of mai sture uptake before and during a freeze/tha w test. Other papers treat the destruction mechanisms behind salt-frost scaling and internai frost attack. There are also papers dealing with the assessment of the service life of concrete exposed to frost action. Same papers present data from field exposure of specimens and from real structures. Altogether, the seminar gives a good picture of what is going on in frost research in the Nordic countries. Almost aU papers, however, treat concrete. There are many more building materials for which frost damage is a problem, but no papers were presented. This does not necessarily mean that work is not done on materials such as clay brick, natural stone, etc, but evidently the activities are much smaller than for concrete. One reason might be that it is much more difficult to find research funding for studies of these types of materials.

Supplementary Cementing Materials for Use in Blended Cements

Provides information on using fly ash, slag, silica fume and natural pozzolans in the manufacturing of blended cements and the effects of these materials on cement and concrete.
Blended cements have been used extensively in Europe but are not common in North America, where supplementary cementing materials are generally added directly to concrete. However, interest in blended cements in North America is growing because of such advantages to the manufacturer as increased production capacity, reduced CO2 emissions and reduced fuel consumption. Blended cements offer a number of potential advantages to the user as well. These include optimized chemistry for sulfate resistance, optimized particle size distributions for low water demand and the desired reactivity, optimized strength gain characteristics, and superior quality control. However, these benefits are not an automatic result of combining clinker with one or more supplementary cementing materials. There is a distinct possibility of making blended cements that are inferior to portland cement if they are not optimized. This report describes the characteristics of the various components that can be used in blended cements and discusses in detail the mechanisms by which they affect each other and the behavior of concrete.By R.J. Detwiler, J.I. Bhatty, and S. BhattacharjaContents1. Introduction2. Materials 2.1 Blended Cement Standards 2.2 Portland Cement Clinker 2.3 Fly Ash 2.3.1 Production and Availability 2.3.2 Definitions and Classifications 2.3.3 Characterization 2.3.4 Need for Improved Specifications 2.3.5 Reactivity 2.3.6 Processing of Fly Ash 2.4 Blast Furnace Slag 2.4.1 Production 2.4.2 Availability 2.4.3 Characterization 2.4.4 Specifications 2.4.5 Reactivity 2.4.6 Processing 2.5 Condensed Silica Fume 2.5.1 Production 2.5.2 Characterization 2.5.3 Availability 2.5.4 Specifications 2.6 Natural and Manufactured Pozzolans 2.7 Limestone 2.8 Rice Husk Ash 2.9 Cement Kiln Dust 2.10 Supplementary Cementing Materials 2.10.1 Pozzolanic properties 2.10.2 Physical effects 2.10.3 Possible impurities3. Behavior of Cement and Concrete Containing Supplementary Cementing Materials 3.1 Workability 3.1.1 Rheology 3.1.2 Effect of Fly Ash 3.1.3 Effect of Slag 3.1.4 Effect of Silica Fume 3.2 Setting and Hydration 3.2.1 Hydration of Cement 3.2.2 Effect of Supplementary Cementing Materials 3.2.2.1 Slag 3.2.2.2 Fly ash 3.2.2.3 Silica fume and rice husk ash 3.3 Compressive Strength 3.3.1 Effect of Supplementary Cementing Materials 3.3.2 Silica Fume 3.3.3 Slag 3.3.4 Fly Ash 3.4 Volume Changes 3.4.1 Plastic Shrinkage 3.4.2 Drying Shrinkage 3.4.3 Soundness 3.4.4 Creep 3.5 Durability 3.5.1 Pore Structure and Permeability 3.5.1.1 Curing at normal temperatures 3.5.1.2 Curing at elevated temperatures 3.5.2 Sulfate Resistance 3.5.3 Carbonation 3.5.4 Corrosion of Reinforcement 3.5.4.1 Mechanism of corrosion in concrete 3.5.4.2 Effect of supplementary cementing materials on corrosion 3.5.5 Alkali-Silica Reactivity 3.5.6 Frost Resistance 3.5.6.1 Mechanisms 3.5.6.2 Effect of silica fume 3.5.6.3 Effect of fly ash 3.5.6.4 Effect of slag 3.6 Interaction with Chemical Admixtures 3.6.1 Water Reducers 3.6.2 Air-entraining Agents 3.6.3 Set-controlling Admixtures4. Optimization 4.1 Background 4.2 Blended Cement Standards 4.2.1 Prescriptive vs. Performance 4.2.2 Building Acceptance 4.3 Obtaining the Desired Properties 4.3.1 Strength and Strength Gain 4.3.2 Durability 4.4 Applications 4.4.1 Checklist for Establishing Criteria 4.4.2 Pavements 4.4.3 Marine Structures 4.4.4 High-rise Buildings 4.4.5 General-use Cement5. Conclusions and Recommendations

Water Resources Systems