Sediments, which constitute the surface of the Earth, start their journey to rivers with the energy obtained from rainfalls, fl oods and other natural processes. Due to transport of sediments, rivers develop with various appearances and functions, and play a crucial role in the activities of human beings and the life cycles of other species.
River sediment, as a conventional topic for river management, has been the topic of continuing research since ancient times, and since then significant progresses in river sediment research has been made. Nowadays, river sediment is much more connected to the activities of mankind and other species, following the increasing awareness of the co-existence of humans and nature.
Advances in River Sediment Research comprises the proceedings of the 12th International Symposium on River Sedimentation (ISRS2013, Kyoto, Japan, 2-5 September 2013). The book contains two keynote papers and 274 peer-reviewed regular contributions from all over the world, and covers recent accomplishments in theoretical developments, numerical simulations, laboratory experiments, field investigations and management methodologies of river sediment related issues. The book may serve as a reference book for graduate students, researchers, engineers and practitioners in disciplines of hydraulic, environmental, agricultural and geological engineering.
Code:
***************************************
Content of this section is hidden, You must be registered and activate your account to see this content. See this link to read how you can remove this limitation:
Safety, Reliability, Risk and Life-Cycle Performance of Structures and Infrastructures
Author: George Deodatis, Bruce R. Ellingwood, Dan M. Frangopol | Size: 470 MB | Format:PDF | Quality:Unspecified | Year: 2014 | pages: 5732 | ISBN: 1138000868
Safety, Reliability, Risk and Life-Cycle Performance of Structures and Infrastructures contains the plenary lectures and papers presented at the 11th International Conference on STRUCTURAL SAFETY AND RELIABILITY (ICOSSAR2013, New York, NY, USA, 16-20 June 2013), and covers major aspects of safety, reliability, risk and life-cycle performance of structures and infrastructures, with special focus on advanced technologies, analytical and computational methods of risk analysis, probability-based design and regulations, smart systems and materials, life-cycle cost analysis, damage assessment, social aspects, urban planning, and industrial applications. Emerging concepts as well as state-of-the-art and novel applications of reliability principles in all types of structural systems and mechanical components are included. Civil, marine, mechanical, transportation, nuclear and aerospace applications are discussed.
The unique knowledge, ideas and insights make this set of a book of abstracts and searchable, full paper USBdevice must-have literature for researchers and practitioners involved with safety, reliability, risk and life-cycle performance of structures and infrastructures.
Code:
***************************************
Content of this section is hidden, You must be registered and activate your account to see this content. See this link to read how you can remove this limitation:
> Presents methodologies for reducing the variability of concrete performance
> Discusses the components of variability (materials, manufacturing, and testing) in terms of quality control
> Examines cost savings and increased business volume due to improved quality practices
> Considers variables such as material handling, mixing, transporting, delivery time, and temperature, and their effects on quality
> Explains how higher quality and lower variability helps with industry sustainability
Summary
Improve the Quality of Concrete, Improve the Quality of Construction
Quality measurement is not prevalent in the concrete industry and quality investment is not seen as potentially generating a positive return. Improving Concrete Quality examines how and why concrete quality should be measured, and includes instruction on developing specifications with the aim of improving concrete quality.
Reduce Concrete Variability: Reduce Costs and Increase Volume
The first part of the book considers the tangible and intangible benefits of improved quality. The later chapters explore concrete strength variability in detail. It provides a greater grasp of the variation in concrete, as well as a deeper understanding of how material variability affects concrete performance. The author discusses the components of variability (material, manufacturing, testing) and provides steps to measuring and reducing variability to improve the quality of concrete. The text also contains a chapter on data analysis for quality monitoring and test results.
Come Away with Practices and Tools That Can Be Applied Immediately:
> Provides techniques and how specifications can improve concrete quality
> Offers a clear understanding of the link between the materials (cement, SCM, aggregate, water, air), manufacturing, testing variability, and concrete quality
> Includes information on analyzing test data to improve quality
Improving Concrete Quality quantifies the benefits of improved quality, and introduces novel ways of measuring concrete quality. This text is an ideal resource for quality personnel in the concrete industry. It also benefits architects, engineers, contractors, and researchers.
Code:
***************************************
Content of this section is hidden, You must be registered and activate your account to see this content. See this link to read how you can remove this limitation:
FOOTFALL INDUCED VIBRATION IN LONGSPAN COMPOSITE STEEL BEAMS USED IN TWO PROJECTS AT THE UNIVERSITY OF AUCKLAND
Author: V.N.Patel and R.J.Built | Size: 1.3 MB | Format:PDF | Quality:Unspecified | Publisher: Steel Innovations Conference 2013 Christchurch, New Zealand 21-22 February 2013 | Year: 2013 | pages: 13
Floor vibration due to human activity has become increasingly recognised by structural engineers, architects, and building owners as an inherent issue in long-span steel framed floor systems. In the past, attention was primarily focused on strength and deflection serviceability limits. However, as designers seek to push the limits on structural spans, grid spacings and adopt light-weight, low damping structural steelwork floor systems, more detailed consideration is required of the design tools and processes available to analyse and predict the vibration performance of floor systems.
Selection from published criteria of an “acceptable” vibration limit is sometimes possible depending upon the intended use of the space and the availability of manufacturers’ data for any vibration sensitive equipment. Building Owners and User Groups often have little understanding or quantitative “feel” for what performance the proposed “acceptable vibration limit” actually represents.
The theoretical predication of vibration performance against actual measured performance can sometimes vary significantly. This can lead to dispute post-construction as to whether the floor has an “acceptable” level of vibration. Post construction remediation of a space that is deemed to be “too lively” is often difficult, therefore, it is important that the vibration design criteria proposed are discussed and agreed and the limits of theoretical predications of vibration performance are clearly understood by all parties at the outset.
Beca Carter Hollings and Ferner Ltd (Beca) are currently in the process of designing two projects at the University of Auckland, utilising long-span partial-composite cellular steel beams. Both buildings will utilise existing structural frame layouts and foundations. As the new structure is to be built on the existing foundations, there is a necessity to keep it as lightweight as possible. The question of vibration sensitivity has been raised as a potential issue as both buildings contain research laboratories. An in-depth investigation has been conducted into the factors affecting vibration performance in order to give the Client and User Groups confidence that footfall induced vibration will not be an issue with the proposed floor structure.
Code:
***************************************
Content of this section is hidden, You must be registered and activate your account to see this content. See this link to read how you can remove this limitation:
Over the last years, the trend in footbridge design has been towards greater spans
and increased flexibility and lightness. As a consequence, stiffness and mass have
decreased which has lead to smaller natural frequencies and more sensitivity to
dynamic loads. Many footbridges have natural frequencies that coincide with the
dominant frequencies of the pedestrian-induced load and therefore they have a potential
to suffer excessive vibrations under dynamic loads induced by pedestrians.
The main focus of this thesis was on the vertical and horizontal forces that
pedestrians impart to a footbridge and how these loads can be modelled to be used
in the dynamic design of footbridges. The work was divided into four subtasks. A
literature study of dynamic loads induced by pedestrians was performed. Design
criteria and load models proposed by four widely used standards were introduced
and a comparison was made. Dynamic analysis of the London Millennium Bridge
was performed using both an MDOF-model and an SDOF-model. Finally, available
solutions to vibration problems and improvements of design procedures were studied.
The standards studied in this thesis all propose similar serviceability criteria
for vertical vibrations. However, only two of them propose criteria for horizontal
vibrations. Some of these standards introduce load models for pedestrian loads
applicable for simplified structures. Load modelling for more complex structures,
on the other hand, are most often left to the designer.
Dynamic analysis of the London Millennium Bridge according to British and
International standards indicated good serviceability. An attempt to model the
horizontal load imposed by a group or a crowd of pedestrians resulted in accelerations that exceeded serviceability criteria.
The most effective way to solve vibration problems is to increase damping by installing a damping system. Several formulas have been set forth in order to calculate
the amount of damping required to solve vibration problems. However, more
data from existing lively footbridges is needed to verify these formulas.
Code:
***************************************
Content of this section is hidden, You must be registered and activate your account to see this content. See this link to read how you can remove this limitation:
Author: Delft University of Technology The Netherlands Faculty of Civil Engineering and Geosciences Department of Design & Construction Section of Structural Engineering Arup Brisbane, Australia Infrastructure, Civil Structures | Size: 18.6 MB | Format:PDF | Quality:Unspecified | Year: 2009 | pages: 140
The last few decades the community demands for more interesting bridges. Improvements in material properties, design methods, building techniques and the involvement of
architects led to longer and slender footbridges. These bridges tend to be more sensitive to dynamic forces induced by pedestrians, resulting in vibrations of the bridge deck. These vibrations can in some cases attain high proportions, especially when the walking pace of the pedestrians approaches the natural frequency of the bridge. Such a case could result in a situation where the pedestrian feel uncomfortable or even unsafe. This topic has thus become an important issue for the Serviceability Limit State of footbridges.
Some Codes of practice nowadays refer to this topic but it is still a developing field.
Dynamic analyses during the design phase have become inevitable. This report compares and evaluates three load models described in the codes (or proposal for the codes):
Proposal Annex C (to EN 1991-2:2003), the British National Annex (to EN 1991-2:2003) and the Australian Standard (AS 5100.2-2004). All three codes have different approaches to this topic. Proposal Annex C considers walking pedestrians (single and groups) and crowds and represent all of them by non moving harmonic loads. The British National Annex also considers joggers which have total different walking pattern. The fundamental difference with the load models described in Proposal Annex C is that the loads are represented by moving harmonic loads. So does the Australian Code, but this one only considers the model of a single pedestrian.
Code:
***************************************
Content of this section is hidden, You must be registered and activate your account to see this content. See this link to read how you can remove this limitation:
Research (academic and industrial) and healthcare facilities contain a number of equipment and procedures that are sensitive to footfall-induced vibrations. Vibration thresholds for these equipment and procedures impose demands on the structural design beyond the typical requirements for strength and serviceability. Vibration engineers typically conduct site measurements and numerical modeling of the floor to assist with the design. The development of practical and accurate numerical models for estimating floor responses is an important component of this process.
Variations in key modeling assumptions can produce impractical and potentially incorrect design recommendations. It is therefore important to be aware of the impacts of modeling assumptions on response predictions. These impacts can be effectively assessed through comparisons of experimental and full scale measurements with numerical prediction models.
In this study, measured floor vibration data from an existing laboratory are used for the development and evaluation of numerical prediction models for footfall vibrations. An existing vibration-sensitive laboratory floor was measured in three configurations: un-furnished pre-retrofit, unfurnished post-retrofit and furnished postretrofit.
Inaccuracies that can arise during floor vibration modeling are highlighted, in addition to the effects of changes to the structural system and the introduction of laboratory furnishings on footfall response levels.
Code:
***************************************
Content of this section is hidden, You must be registered and activate your account to see this content. See this link to read how you can remove this limitation:
***************************************
Content of this section is hidden, You must be registered and activate your account to see this content. See this link to read how you can remove this limitation:
Floor vibration serviceability has become an area of interest over recent years. Lightweight electronic offices, especially those with slender architectural forms, and high-technology buildings with low vibration environments can often have excessive floor vibration due to human walking. This can result in a floor which is not fit-forpurpose.
There exist a number of design guides which offer simplified formulae toanalyse these floors. However, the simplistic methods are often shown in be inaccurate and inappropriate. The alternative, finite element analysis (FEA), which is often considered more accurate, can be expensive to implement and time consuming. In addition, modelling techniques required for dynamic analyses are different to that required for static analysis. This is often overlooked, resulting in poor inaccurate models. An accurate, simplistic, method is required which is suitable for everyday design.
This paper examines the current simplified methods of predicting floor response to a single human walking. The inaccuracies are highlighted, as well as where the methodology is inappropriate. The paper also introduces new techniques and ideas to improve design guides in the future.
Code:
***************************************
Content of this section is hidden, You must be registered and activate your account to see this content. See this link to read how you can remove this limitation:
Several ski companies have recently introduced vibration damping
features in their product lines. These features are designed to improve the
performance of the ski and lessen felt shock. Three brands of vibration damping
systems were tested to determine the effectiveness of the damping features.
Similar skis without damping systems were also tested. The systems were tested
in the lab and on the hill. In the lab the systems were subjected to a variety of
random inputs and their responses recorded. On the hill the data was collected
from the ski and binding as the ski was being used. A portable data collection
system carried by the skier was employed to gather information. It was found that
two of the systems did reduce vibrations and transmitted shock over ranges of the
frequency spectrum. An error in the data collection process prevented a
determination of the effectiveness of the third damping system.
Code:
***************************************
Content of this section is hidden, You must be registered and activate your account to see this content. See this link to read how you can remove this limitation:
![[Image: 50726071617034703240.jpg]](https://pic.civilea.com/images/50726071617034703240.jpg)
![[Image: info.png]](http://postgen.civilea.com/icon/info.png){kind=icon}
![[Image: download.png]](http://postgen.civilea.com/icon/download.png){kind=icon}
![[Image: 00574129937457474208.jpg]](https://pic.civilea.com/images/00574129937457474208.jpg)
![[Image: 47174789033241831520.jpg]](https://pic.civilea.com/images/47174789033241831520.jpg)
![[Image: 25466995927597650187.png]](https://pic.civilea.com/images/25466995927597650187.png)
![[Image: 79158596676408726379.png]](https://pic.civilea.com/images/79158596676408726379.png)
![[Image: 71480356459463382109.png]](https://pic.civilea.com/images/71480356459463382109.png)
![[Image: 03279550113916258076.png]](https://pic.civilea.com/images/03279550113916258076.png)
![[Image: 84014676050752813094.png]](https://pic.civilea.com/images/84014676050752813094.png)