scholarly journals Assessment of the Lateral Vibration Serviceability Limit State of Slender Footbridges Including the Postlock-in Behaviour

2020 ◽  
Vol 10 (3) ◽  
pp. 967 ◽  
Author(s):  
Rocío G. Cuevas ◽  
Javier F. Jiménez-Alonso ◽  
Francisco Martínez ◽  
Iván M. Díaz
Keyword(s):  
Limit State ◽  
Sudden Onset ◽  
Design Guidelines ◽  
Comfort Level ◽  
Lateral Vibration ◽  
Vibration Serviceability ◽  
Current Design ◽  
Common Criterion ◽  
Lock In Effect ◽  
Lock In

The lateral vibration serviceability of slender footbridges has been the subject of many studies over the last few decades. However, in spite of the large amount of research, a common criterion has not been set yet. Although the human–structure interaction phenomenon is widely accepted as the main cause of the sudden onset of high amplitudes of vibration, the current design recommendations do not include an expression for the auto-induced component of the pedestrian action and, as a consequence, it is not possible to evaluate the footbridge comfort once the lock-in effect has developed. Hence, the purpose of this paper is to propose a general formulation, which allows the analysis of the different load scenarios that the footbridge will experience during its overall life cycle. An important advantage over most current design guidelines is that the procedure permits the evaluation of the comfort level of the footbridge, even with crowd densities above the “critical number”, and thus takes informed decisions about the possible use of external devices to control the vibration response, depending on the probability of occurrence of the problem. The performance of the proposed method is successfully evaluated through numerical response simulations of two real footbridges, showing a good agreement with the experimental data.

Flexural design of precast, prestressed ultra-high-performance concrete members

PCI Journal ◽  
2020 ◽  
Vol 65 (6) ◽  
pp. 35-61
Author(s):  
Chungwook Sim ◽  
Maher Tadros ◽  
David Gee ◽  
Micheal Asaad
Keyword(s):  
Prestressed Concrete ◽  
High Performance ◽  
High Performance Concrete ◽  
Limit State ◽  
Design Guidelines ◽  
Design Tool ◽  
Supplementary Cementitious Materials ◽  
Ultra High Performance Concrete ◽  
Concrete Members ◽  
Cylinder Strength

Ultra-high-performance concrete (UHPC) is a special concrete mixture with outstanding mechanical and durability characteristics. It is a mixture of portland cement, supplementary cementitious materials, sand, and high-strength, high-aspect-ratio microfibers. In this paper, the authors propose flexural design guidelines for precast, prestressed concrete members made with concrete mixtures developed by precasters to meet minimum specific characteristics qualifying it to be called PCI-UHPC. Minimum specified cylinder strength is 10 ksi (69 MPa) at prestress release and 18 ksi (124 MPa) at the time the member is placed in service, typically 28 days. Minimum flexural cracking and tensile strengths of 1.5 and 2 ksi (10 and 14 MPa), respectively, according to ASTM C1609 testing specifications are required. In addition, strain-hardening and ductility requirements are specified. Tensile properties are shown to be more important for structural optimization than cylinder strength. Both building and bridge products are considered because the paper is focused on capacity rather than demand. Both service limit state and strength limit state are covered. When the contribution of fibers to capacity should be included and when they may be ignored is shown. It is further shown that the traditional equivalent rectangular stress block in compression can still be used to produce satisfactory results in prestressed concrete members. A spreadsheet workbook is offered online as a design tool. It is valid for multilayers of concrete of different strengths, rows of reinforcing bars of different grades, and prestressing strands. It produces moment-curvature diagrams and flexural capacity at ultimate strain. A fully worked-out example of a 250 ft (76.2 m) span decked I-beam of optimized shape is given.

The Capital Gains Lock-In Effect and Earnings Quality

2019 ◽  
Author(s):  
Stephen G. Dimmock ◽  
Fan Feng ◽  
Huai Zhang
Keyword(s):  
Earnings Quality ◽  
Capital Gains ◽  
Lock In Effect ◽  
Lock In

Front steering design guidelines formulation for e-scooters considering the influence of sitting and standing riders on self-stability and safety performance

2021 ◽  
pp. 095440702199217
Author(s):  
Milan Paudel ◽  
Fook Fah Yap
Keyword(s):  
Preventive Measures ◽  
Recent Trend ◽  
Dynamic Performance ◽  
Design Guidelines ◽  
Safety Performance ◽  
Design Parameters ◽  
Single Track ◽  
Standing Posture ◽  
Last Mile ◽  
Current Design

E-scooters are a recent trend and are viewed as a sustainable solution to ease the first and last mile problem in modern transportation. However, an alarming rate of accidents, injuries, and fatalities have caused a significant setback for e-scooters. Many preventive measures and legislation have been put on the e-scooters, but the number of accidents and injuries has not reduced considerably. In this paper, the current design approach of e-scooters has been analyzed, and the most common range of design parameters have been identified. Thereafter, validated mathematical models have been used to quantify the performance of e-scooters and relate them with the safety aspects. Both standing and seated riders on e-scooters have been considered, and their influence on the dynamic performance has been analyzed and compared with the standard 26-in wheel reference safety bicycle. With more than 80% of the accidents and injuries occurring from falling or colliding with obstacles, this paper tries to correlate the dynamics of uncontrolled single-track vehicles with the safety performance of e-scooters. The self-stability, handling, and braking effect have been considered as major performance matrices. The analysis has shown that the current e-scooter designs are not as stable as the reference safety bicycle. Moreover, these e-scooters have been found unstable within the most common range of legislated riding velocity. The results corroborate with the general perception that the current designs of e-scooters are less stable, easy to lose control, twitchy, or wobbly to ride. Furthermore, the standing posture of the rider on the e-scooter has been found dangerous while braking to avoid any disturbances such as potholes or obstacles. Finally, the front steering design guidelines have been proposed to help modify the current design of e-scooters to improve the dynamic performance, hence the safety of the e-scooter riders and the surroundings.

scholarly journals Informal Reform of the United Nations Security Council

2018 ◽  
Vol 40 (1) ◽  
pp. 97-115
Author(s):  
Mariana Pimenta Oliveira Baccarini
Keyword(s):  
Cold War ◽  
United Nations ◽  
Security Council ◽  
United Nations Security Council ◽  
Decision Making Process ◽  
Institutional Perspective ◽  
The United Nations ◽  
Lock In Effect ◽  
The Cold War ◽  
Lock In

Abstract This article analyses attempts to reform the United Nations Security Council from a historical-institutional perspective. It argues that the possibilities for reform have suffered from a ‘lock-in’ effect that has rendered the UN resistant to change. On the other hand, the UN decision-making process has evolved since its establishment, especially since the end of the Cold War, in response to new power aspirations, making it more representative and legitimate. The Security Council has also undergone continuous informal reform that has allowed it to adapt to new times.

Complaint behaviour in multichannel retailing: a cross-stage approach

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Marta Frasquet ◽  
Marco Ieva ◽  
Cristina Ziliani
Keyword(s):  
Online Survey ◽  
Latent Class ◽  
Service Failure ◽  
Service Recovery ◽  
Content Type ◽  
Multichannel Retailing ◽  
Synergy Effects ◽  
Lock In Effect ◽  
Lock In ◽  
Post Purchase

PurposeThis paper analyses how the purchase channel and customer complaint goals affect the sequential choice of post–purchase complaint channels when customers experience a service failure followed by a service recovery failure (double deviation).Design/methodology/approachAn online survey involving a scenario manipulation was conducted with 577 apparel shoppers. The study employs multi-group latent class analysis to estimate latent customer segments within both online and offline groups of shoppers and compare latent classes between the two groups.FindingsThe results show that the purchase channel has a lock-in effect on the complaint channel, which is stronger for offline buyers. Moreover, there is evidence of channel synergy effects in the case of having to complain twice: shoppers who complain in store in the first attempt turn to online channels in the second complaint attempt, and vice versa. Complaint goals shape the choice of complaint channels and define different shopper segments.Originality/valueThe present study is the first to adopt a cross-stage approach that analyses the dependencies between the purchase channel and the complaint channel used on two subsequent occasions: the first complaint after a service failure and the second following a service recovery failure.

Theoretical and Experimental Study on the Ultimate Strength of Corrugated Bulkheads

1997 ◽  
Vol 41 (04) ◽  
pp. 301-317
Author(s):  
Jeom K. Paik ◽  
Anil K. Thayamballi ◽  
Min S. Chun
Keyword(s):  
Ultimate Strength ◽  
Lateral Pressure ◽  
Limit State ◽  
Plate Thickness ◽  
Experimental Information ◽  
Design Guidelines ◽  
Design Parameters ◽  
Collapse Mechanism ◽  
Ultimate Limit State ◽  
Analytical Formulation

The objectives of the present study are to obtain experimental data on collapse strength of steel corrugated bulkhead models and also to develop a simple analytical formulation for ultimate strength useful in the design of corrugated bulkheads under static lateral pressure. Collapse tests on nine mild steel corrugated bulkhead models having five bays of corrugations are carried out, varying the corrugation angle, the plate thickness and the type of loading (axial compression and/or lateral pressure). Using the test data, the characteristics of the collapse mechanism for corrugated bulkheads are investigated. For purposes of rapid first cut estimates of strength, a new and simple analytical formulation for predicting the ultimate strength of corrugated bulkheads under hydrostatic pressure is derived based on an assumed stress distribution over the corrugation cross section at the ultimate limit state. The modeling error associated with the new formulation is established by comparing its predictions with the experimental results. The development of ultimate strength based design guidelines and the effect of design parameters such as the corrugation angle on ultimate strength of a corrugated bulkhead are then discussed. All experimental information and strength data are tabulated, which is a benefit in itself.

Germany's Repeal of the Corporate Capital Gains Tax: The Equity Market Response

2004 ◽  
Vol 26 (s-1) ◽  
pp. 73-97 ◽  
Author(s):  
Courtney H. Edwards ◽  
Mark H. Lang ◽  
Edward L. Maydew ◽  
Douglas A. Shackelford
Keyword(s):  
Abnormal Returns ◽  
Economic Effects ◽  
Capital Gains ◽  
Capital Gains Tax ◽  
Cross Sectional ◽  
Price Response ◽  
Corporate Capital ◽  
Market Values ◽  
Lock In Effect ◽  
Lock In

In late 1999, the German government made a surprise announcement that it would repeal the large and long-standing capital gains tax on sales of corporate crossholdings effective in 2002. The repeal has been hailed as a revolutionary step toward breaking up the extensive web of crossholdings among German companies. The lock-in effect from the large corporate capital gains tax was said to act as a barrier to efficient acquisition and divestiture of German firms and divisions. Many observers predicted that once the lock-in effect was removed, Germany would experience a flurry of acquisition and divestiture activity. Several other industrialized countries were poised to follow suit, with similar proposals pending in France, Japan, and the United Kingdom. This paper provides evidence of the economic impact of the repeal by examining its effect on the market values of German firms. While event studies of tax legislation can be difficult, our study is aided by the fact that the repeal was both a surprise and was announced separately from other tax reform proposals. In addition, we provide cross-sectional evidence on the economic magnitude of the repeal, assess the likely beneficiaries from the repeal, and predict which sectors are most likely to experience a surge in acquisition and divestiture activity following the repeal. Our results suggest that the economic effects are highly concentrated. We find a positive association between firms' event period abnormal returns and the extent of their crossholdings, consistent with taxes acting as a barrier to efficient allocation of ownership. However, the reaction is limited to the six largest banks and insurers and their extensive minority holdings in industrial firms. These six large firms have a combined market capitalization equal to 22 percent of all 394 firms in this study. We also find evidence of a positive stock price response to the announcement for industrial companies held by these financial firms, consistent with shareholders in those firms benefiting from the likely reduction in investor-level tax burdens and expected increased efficiency following the tax law change.

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