scholarly journals The Effects of Deteriorated Boundary Conditions on Horizontally Framed Miter Gates

Metals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 37
Author(s):  
Guillermo A. Riveros ◽  
Felipe J. Acosta ◽  
Christine M. Lozano ◽  
Eileen Glynn
Keyword(s):  
Analytical Solutions ◽  
Steel Structures ◽  
River System ◽  
Limit States ◽  
Design Life ◽  
Fundamental Understanding ◽  
Bolt Failure ◽  
Shear Cracking ◽  
Different Levels ◽  
The U.S

The U.S. navigable infrastructure is a system of waterways dependent upon hydraulic steel structures (HSS) to facilitate the passage of ships and cargo. The system is linear in the sense that if one HSS is impassable, the entire river system is halted at that point. The majority of the HSS in this system were built in the first half of the 20th Century, and over seventy percent of them are past or near past their design life. Miter gates are critical HSS components within the system and many are showing signs of structural distress from continued operation past their design life. Common distress features include shear cracking within the pintle socket, partially missing Quoin blocks, fatigue fracturing, and bolt failure in the pintle region. This article focuses on gaining a fundamental understanding of the consequences of quoin block deterioration on a miter gate. The work was conducted by developing a computational model of a miter gate with different levels of quoin block deterioration. This model was validated using analytical solutions. The deterioration results demonstrated that the miter gate thrust diaphragm and quoin post experienced changes in their limit states due to deterioration. The results also demonstrated that the miter gate could overcome up to 10% of quoin block deterioration.

scholarly journals Classical and innovative methods of fatigue and fracture repairs in navigation steel structures

2021 ◽  
Author(s):  
Lozano Christine ◽  
Riveros Guillermo
Keyword(s):  
Fatigue Cracking ◽  
Steel Structures ◽  
Load Carrying Capacity ◽  
Limit States ◽  
New Methods ◽  
Innovative Methods ◽  
Design Life ◽  
Load Carrying ◽  
Fatigue And Fracture ◽  
The U.S

Most of the hydraulic steel structures (HSS) in the U.S. have reached or have past their design life, which leads to unsatisfactory performance. Welded connections with low fatigue resistance, poor weld quality, unanticipated structural behavior, or unexpected loading due to the deterioration of the design boundary conditions are the causes of fatigue cracking. The purpose of this report is to identify and evaluate the traditional and new methods used for fatigue and fracture repairs in navigation steel structures to restore their load carrying capacity and fatigue and fracture resistance. The final objective was to generate a guidance report comprising of recommended and more efficient repair methods for the different fatigue limit states observed in navigation steel structures.

scholarly journals Partial factors for cross-section resistance of elements in steel structures

2013 ◽  
Vol 12 (2) ◽  
pp. 213-220
Author(s):  
Marian Giżejowski ◽  
Zbigniew Stachura
Keyword(s):  
Cross Section ◽  
Steel Structures ◽  
Partial Cross Section ◽  
Live Load ◽  
Practical Application ◽  
Limit States ◽  
Resistance Factors ◽  
Safety Requirements ◽  
Permanent Load ◽  
Load Component

Issues related to safety requirements for steel elements subjected to different stress resultants in reference to limit states design philosophy according to Structural Eurocodes PN-EN and national codes PN-B are dealt with in the paper. The calibration of partial cross-section resistance factors is discussed on the basis of elements of steel floor structures where the permanent load component and the live load component of variable actions are the only components of load combinations. Final conclusions for their practical application in the codification process are formulated and values of partial factors for cross section resistance are proposed.

scholarly journals The Effect of slit-friction hybrid damper on the Performance of Dual System

2019 ◽  
Vol 13 (1) ◽  
pp. 271-280
Author(s):  
Azadeh Khoshkroodi ◽  
Hossein Parvini Sani
Keyword(s):  
Time History ◽  
Steel Structures ◽  
Repair Cost ◽  
Friction Dampers ◽  
History Analysis ◽  
Different Types ◽  
Moment Resisting ◽  
Hybrid Damper ◽  
Large Earthquakes ◽  
Different Levels

Aims: The aim of the present paper is to evaluate the behavior of slit friction hybrid dampers (SFHD) on steel structures. Therefore, the behavior moment resisting steel frames of structures in original stats and structures equipped with hybrid damper with two different types of behavior was analyzed and evaluated. Background: The recent study evaluated the combined effect of shear-friction dampers and slit dampers with measurements of non-uniform strips in seismic protection for different levels of energy. The recent study was carried out a about hybrid dampers, consisting of friction and split dampers in response to small and large earthquakes. Previous results have shown the ability of inactive hybrid systems in improving the reaction of structures to traditional lateral-systems. Kim and Shin showed that structures consisted of hybrid dampers needed less repair cost and time. Methods: Pushover and time history were carried out on original structures and structures equipped with dampers, in 5 and 10 stories structures. Results: Analysis about the probability of collapse showed about 30% and 84%. Conclusion: According to the result, by adding the SFHD, increased stiffness by 17% in retrofitted structures such as drift and displacement of roof decreases by 27% and 20% in push over analysis, respectively. Also, displacement in time history analysis up to 55% reduces in average. Also, the results of the IDA show that adding the SFHD to structures significantly increases by 55% the spectral acceleration capacity in structures.

Transitional Leadership

2017 ◽  
Author(s):  
Thomas G. Bradbeer
Keyword(s):  
Korean War ◽  
Second World War ◽  
World War ◽  
Military Academy ◽  
Chief Of Staff ◽  
The Korean War ◽  
Eighth Army ◽  
Second World ◽  
Different Levels ◽  
The U.S

Matthew B. Ridgway was an influential American airborne commander during the Second World War and led United Nations forces during the Korean War. A 1917 graduate of the U.S. Military Academy, Ridgway served multiple tours in Latin America and Asia as a junior and mid-grade officer. A protégée of General George Marshall, he commanded the Eighty-Second airborne division during the invasions of Sicily, Italy, and France. During the Battle of Bulge and the invasion of Germany, he served as commander of the newly created Eighteenth Airborne Corps. Years later, during the Korean War, Ridgway transitioned from a staff position as a deputy to Army Chief of Staff Lawton Collins to become commander of the Eighth Army in Korea, and then commander of all U.N. forces in the Korean theatre. Ridgway's career, especially his leadership during the two wars, provides insights on the officer skills needed to effectively transition to different levels of command.

scholarly journals Calibrating Partial Factors – Methodology, Input Data and Case Study of Steel Structures

2019 ◽  
Author(s):  
Vitali Nadolski ◽  
Árpád Rózsás ◽  
Miroslav Sýkora
Keyword(s):  
Input Data ◽  
Structural Reliability ◽  
Construction Materials ◽  
Steel Structures ◽  
Structural Performance ◽  
Limit States ◽  
Different Types ◽  
Load Effects ◽  
Previous Design

Partial factors are commonly based on expert judgements and on calibration to previous design formats. This inevitably results in unbalanced structural reliability for different types of construction materials, loads and limit states. Probabilistic calibration makes it possible to account for plentiful requirements on structural performance, environmental conditions, production and execution quality etc. In the light of ongoing revisions of Eurocodes and the development of National Annexes, the study overviews the methodology of probabilistic calibration, provides input data for models of basic variables and illustrates the application by a case study. It appears that the partial factors recommended in the current standards provide for a lower reliability level than that indicated in EN 1990. Different values should be considered for the partial factors for imposed, wind and snow loads, appreciating the distinct nature of uncertainties in their load effects.

Seismic retrofit of structures using rotational friction dampers with restoring force

2020 ◽  
Vol 23 (16) ◽  
pp. 3525-3540
Author(s):  
Asad Naeem ◽  
Jinkoo Kim
Keyword(s):  
Ground Motions ◽  
Design Procedure ◽  
Steel Structures ◽  
Friction Damper ◽  
Heavy Duty ◽  
Limit States ◽  
Restoring Force ◽  
Friction Dampers ◽  
Torsional Spring ◽  
Capacity Spectrum

In this study, the seismic performance of a rotational friction damper with restoring force is presented. The torsional spring friction damper consists of rotational friction pads with the heavy duty torsional springs attached on both sides of the friction damper. An analytical model and a design procedure for the damper are developed using capacity spectrum method. A parametric study is carried out to investigate the influence of the torsional spring in the response of the structure when subjected to ground motions. The seismic performances of steel structures retrofitted with the torsional spring friction damper and conventional rotational friction dampers are evaluated using fragility analysis, which shows that the structure retrofitted with the torsional spring friction damper has the smallest probability of reaching the specific limit states.

Limit States Design and Partial Factors γM0 and γM1 in Metal Eurocodes

2016 ◽  
Vol 821 ◽  
pp. 774-781
Author(s):  
Ivan Balaz ◽  
Yvona Kolekova
Keyword(s):  
Steel Structures ◽  
Limit States ◽  
Current Value

Overview of values and definitions of material partial factors γM0 and γM1 used in all 20 parts of Eurocodes EN 1993 Design of steel structures [1] and in all 5 parts of EN 1999 Design of aluminium structures [2]. Applications of the γM0 and γM1 partial factors values and definitions in all clauses of EN 1993. Comparison of safety levels of former Czechoslovak standards (ČSN) with current Eurocodes. Proposals for correction of definitions and applications of γM0 and γM1 partial factors in all clauses of EN 1993. The overview and corrections enable to do better choice from five official options aiming to change current value γM1 = 1,0 valid in EN 1993-1-1 for buildings, which were presented at CEN/TC250 SC3 meetings in October 24th 2014 and in March 19th 2015 in Berlin.

An assessment of CSA standard equations for beam column design

1981 ◽  
Vol 8 (2) ◽  
pp. 130-136 ◽  
Author(s):  
S. U. Pillai
Keyword(s):  
Steel Structures ◽  
Limit States ◽  
Beam Columns ◽  
Detailed Procedure ◽  
Standard Lead ◽  
Column Design

Comparisons are made between results of 81 recent tests on beam columns subjected to unsymmetrical and biaxially eccentric loads and the capacities predicted by design equations recommended by CSA standard S16.1-M78 — Steel Structures for Buildings — Limit States Design. It is concluded that the general provisions of the standard lead to satisfactory designs whereas the detailed procedure given in the Appendix of the standard may lead to a higher proportion of unsafe results.

scholarly journals Meta-Strategic Lobbying: The 1998 Steel Imports Case

2005 ◽  
Vol 7 (1) ◽  
pp. 1-24 ◽  
Author(s):  
Douglas A. Brook
Keyword(s):  
Steel Industry ◽  
The United States ◽  
Factors Affecting ◽  
Policy Choices ◽  
Strategic Approach ◽  
Almost All ◽  
Governmental Response ◽  
Comparative Examination ◽  
Different Levels ◽  
The U.S

In 1998, the domestic steel industry in the United States devised and executed a complex and sophisticated effort to achieve an effective non-market response to a sudden, persistent, and damaging surge of imported steel. This campaign lasted until 2002, when President George W. Bush invoked Section 201 of the U.S. trade laws to impose tariffs on imports of most steel products. This case of the steel industry's trade policy campaign provides an opportunity to examine selected models of protection-seeking industries and lobbying to ask why and how the steel coalition achieved this extraordinary governmental response. These questions are explored though a descriptive case of the steel industry's protection-seeking campaign followed by a comparative examination of previous models of protection-seeking firms, and lobbying to achieve protectionist policies. A comparison with selected models of the determinants of protection-seeking and factors affecting lobbying strategies show that most, almost all, were present in the steel case. In fact, a meta-strategic approach that transcends the customary understanding of lobbying is suggested in a complex policy environment. Such an environment can be characterized by: the need to influence multiple governmental entities – legislative, regulatory, executive; the desire for multiple outcomes with varying levels of specificity – laws or resolutions, administrative rulings, policy choices; interactions between different levels and branches of government; employment of coordinated interrelated lobbying techniques; and simultaneity of these factors.

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