LOAD PATH REFORMULATION AROUND MULTIPLE RESTRICTIONS FOR AN INDUSTRIAL RETROFIT

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Tim Hogue
Keyword(s):  
Structural Steel ◽  
Regulatory Compliance ◽  
Lessons Learned ◽  
Industrial Plant ◽  
Structural Members ◽  
Load Path ◽  
Moment Frames ◽  
Load Paths ◽  
Construction Schedule ◽  
Existing Structure

Process, operational, and electrical restrictions inherent in the design of a regulatory compliance upgrade for an industrial plant, and overburdened existing structure, required an unusual structural retrofit. There were multiple restrictions on placement of structural members and multiple needs for additional strength in the existing members. To manage the constraints, the load path was reformulated to bypass problem areas and focus upgrade work on just a few locations. The key in selecting upgrade locations was determining where there was reserve capacity in the existing foundation. Two such locations were identified and super-bents were formed there using existing moment frames. Horizontal trusses were built to bridge between the super-bents. A super-bent included a new grade beam, with end bulbs surrounding existing column pedestals, column section augmentation, new heavy anchor bolts and new diagonals to convert two parallel beams into a deep truss. Embedded structural steel was utilized in the grade beam end bulbs to distribute anchorage forces and develop reliable load paths around obstructed columns. Unusual uses of structural steel, work in obscured areas, unconventional structural systems and construction schedule interruptions led to an increase in construction management and inspection scope and complexity. CM lessons learned from the project involved better interaction of disciplines during design and greater input from engineering just prior to and during construction.

Learnings from the Field Implementation of a Novel Ultra-High Performance Concrete Beam End Repair on a Corroded Steel Girder Bridge in Connecticut

2021 ◽  
pp. 036119812110041
Author(s):  
Alexandra Hain ◽  
Arash E. Zaghi
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Implementation Process ◽  
Lessons Learned ◽  
Load Path ◽  
Ultra High Performance Concrete ◽  
Steel Girder Bridge ◽  
Aging Steel ◽  
Girder Bridge ◽  
The University

Corrosion at steel beam ends is one of the most pressing challenges in the maintenance of aging bridges. To tackle this challenge, the Connecticut Department of Transportation (DOT) has partnered with the University of Connecticut to develop a repair method that benefits from the superior mechanical and durability characteristics of ultra-high performance concrete (UHPC) material. The repair involves welding shear studs to the intact portions of the web and encasing the beam end with UHPC. This provides an alternate load path for bearing forces that bypasses the corroded regions of the beam. The structural viability of the repair has been extensively proven through small- and full-scale experiments and comprehensive finite element simulations. Connecticut DOT implemented the repair for the first time in the field on a heavily trafficked four-span bridge in 2019. The UHPC beam end repair was chosen because of the access constraints and geometric complexities of the bridge that limited the viable repair options. Four of the repaired beam ends were fully instrumented to collect data on the performance of the repaired locations before casting, during curing, and for approximately 6 months following the application of the repair. This paper provides an overview of the successful repair implementation and presents the lessons learned during construction. Select data from the monitored beam ends are presented. It is expected that this information will provide engineers with a better understanding of the repair implementation process, and thus provide an additional repair option for states to enhance the safety of aging steel bridges.

scholarly journals Influence Of Large Non-Metallic Inclusions On Bending Fatigue Strength Hardened And Tempered Steels

2015 ◽  
Vol 15 (3) ◽  
pp. 33-40
Author(s):  
T. Lipiński ◽  
A. Wach ◽  
E. Detyna
Keyword(s):  
Fatigue Strength ◽  
Structural Steel ◽  
Treatment Options ◽  
Fatigue Tests ◽  
Relative Volume ◽  
Heat Processing ◽  
Industrial Plant ◽  
Boron Steel ◽  
Metallic Inclusions ◽  
Steel Sections

Abstract The article discusses the effect of large oxide impurities (a diameter larger than 10 μm in size) on the fatigue resistance of structural steel of high purity during rotary bending. The study was performed on 7 heats produced in an industrial plant. The heats were produced in 140 ton electric furnaces. All heats were desulfurized. The experimental material consisted of semi-finished products of high-grade, carbon structural steel with: manganese, chromium, nickel, molybdenum and boron. Steel sections with a diameter of 18 mm were hardened from austenitizing by 30 minutes in temperature 880°C and tempered at a temperature of 200, 300, 400, 500 and 600°C for 120 minutes and air-cooled. The experimental variants were compared in view of the heat treatment options. Fatigue tests were performed with the use of a rotary bending machine at a frequency of 6000 cpm. The results were statistical processed and presented in graphic form. This paper discusses the results of the relative volume of large impurities, the fatigue strength for various heat processing options.

Analysis of Structural Steel Renewal Locations in Ship Repairing

2021 ◽  
Vol 37 (01) ◽  
pp. 1-36
Author(s):  
Arun Kr Dev ◽  
Makaraksha Saha
Keyword(s):  
Structural Steel ◽  
Prior Information ◽  
Idle Time ◽  
Structural Members ◽  
Related Information ◽  
Routine Work ◽  
Operational Life

Structural steel renewal in ship repairing is a routine work throughout the service/ operational life of a ship. Prior information about the renewal quantity helps the shipowners to allocate an appropriate budget and the shipyard to prepare the proper ship repairing schedule. It, in turn, helps the shipowners make a financial commitment for cargo. Likewise, prior information about the location of steel renewal works can help the shipowners to prepare the ship before going to the shipyard and the latter to plan for the required logistics. By doing so, the shipowners would be able to save cost in terms of less idle time in the shipyard. The latter can also increase the revenue in terms of minimizing mobilization time. Structural steel renewal location-related information for 123 cargo ships of various ages, deadweights, and types were collected from a single shipyard. Data of renewal locations of selected structural members were analyzed and presented in both tabular and graphical forms. The intention was to show the behavior of renewal locations with respect to the ship’s dimension appropriate for respective structural members, age, and length of the ship. In this article, the authors have attempted to identify and establish the possible root causes that influence the renewal locations and also to investigate and suggest the potential interrelationships between renewal locations, age, length, and type.

Load Path Transmission in Joining Elements

2021 ◽  
Vol 883 ◽  
pp. 73-80
Author(s):  
Christian Steinfelder ◽  
Sven Martin ◽  
Alexander Brosius ◽  
Thomas Tröster
Keyword(s):  
Path Analysis ◽  
Fe Model ◽  
3D Analysis ◽  
Tensile Shear ◽  
Load Path ◽  
Element Analysis ◽  
Transmission Path ◽  
Future Design ◽  
Load Transmission ◽  
Load Paths

The mechanical properties of joined structures are determined considerably by the chosen joining technology. With the aim of providing a method that enables a faster and more profound decision-making in the spatial distribution of joining points during product development, a new method for the load path analysis of joining points is presented. For an exemplary car body, the load type in the joining elements, i.e. pure tensile, shear and combined tensile-shear loads, is determined using finite element analysis (FEA). Based on the evaluated loads, the resulting load paths in selected joining points are analyzed using a 2D FE-model of a clinching point. State of the art methods for load path analysis are dependent on the selected coordinate system or the existing stress state. Thus, a general statement about the load transmission path is not possible at this time. Here, a novel method for the analysis of load paths is used, which is independent of the alignment of the analyzed geometry. The basic assumption of the new load path analysis method was confirmed by using a simple specimen with a square hole in different orientations. The results presented here show a possibility to display the load transmission path invariantly. In further steps, the method will be extended for 3D analysis and the investigation of more complex assemblies. The primary goal of this methodical approach is an even load distribution over the joining elements and the component. This will provide a basis for future design approaches aimed at reducing the number of joining elements in joined structures.

An Educational Elasticity Problem With Friction, Part 3: General Load Paths

1983 ◽  
Vol 50 (1) ◽  
pp. 77-84 ◽  
Author(s):  
J. Dundurs ◽  
M. Comninou
Keyword(s):  
Elasticity Problem ◽  
Exact Nature ◽  
Load Path ◽  
Initial State ◽  
Concentrated Force ◽  
Load Paths

This concluding paper treats general load paths when the two components of the concentrated force are allowed to change independently with time. It is shown that there are two kinds of dependence on the load path. For certain directions of the forward tangent, the dependence is strict in that the deformations depend on the full details of the path. For other directions, however, the dependence is loose, and the deformations do not depend on the exact nature of the path as long as the forward tangent falls within given bounds. The problem also shows that, given an initial state, the load space can be subdivided into different regions each corresponding to a certain mode of deformations.

scholarly journals The Route That Forces Take

2008 ◽  
Vol 130 (09) ◽  
pp. 39-42
Author(s):  
James G. Skakoon
Keyword(s):  
Human Factor ◽  
Mechanical Design ◽  
Design Tool ◽  
Engineering Analysis ◽  
Force Transmission ◽  
Load Path ◽  
Analytical Design ◽  
Load Paths ◽  
Potential Problems ◽  
Factor Design

This article discusses that visualizing the load path in a design can uncover areas open to improvement. Planning the force transmission path during mechanical design is hardly dazzling engineering analysis, but explicitly doing so will improve your designs. By visualizing the transmission of forces, one can eliminate unnecessary parts, strengthen the design, and identify potential problems for further analysis or correction. Visualizing the path of transmitted forces for cables is pretty easy; forces follow the tension cables. But it is only slightly more complex with compression and shear involved. Although design is never a strictly linear progression, reviewing and refining the load path should be a formal part of the design process. Troubles with the load path in user-centered device design may become obvious with testing, but thinking about load paths as a human factor design issue can save time and effort. It is not a highly analytical design tool, but visualizing and refining load paths in structures and mechanisms is extraordinarily useful for designers, and it’s simple.

scholarly journals Alternative Load Path Analysis for Assessing the Geometric Agreement of a Cable-Stayed Bridge with Steel Truss Girders

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Xiaobo Zheng ◽  
Gang Zhang ◽  
Yongfei Zhang ◽  
Leping Ren
Keyword(s):  
Computer Software ◽  
Element Model ◽  
Load Path ◽  
Brittle Damage ◽  
Cable Stayed Bridge ◽  
Load Paths ◽  
Vehicle Loading ◽  
Bridge Collapse ◽  
Steel Truss ◽  
Collapse Behavior

The geometric agreement, commonly hailed as load-transferring paths withinbridge structures, is significantly crucial to the bridge structural mechanicalperformance, such as capacity, deformation, and collapse behavior. This paperpresents a methodology dependent on alternative load paths to investigate thecollapse behavior of a double-pylon cable-stayed bridge with steel truss girderssubjected to excess vehicle loading. The cable-stayed bridge with steel trussgirders is simplified using a series-parallel load-bearing system. This researchmanifests that the enforced vehicle loading can be transferred to alternativepaths of cable-stayed bridges in different load-structure scenarios. A 3-Dfinite element model is established utilizing computer software ANSYS to explorethe collapse path of cable-stayed bridge with steel truss girders, taking intoaccount chord failure, loss of cables together with corrosion in steel trussgirders. The results show that chord failures in the mid-portion of the mainspan result in brittle damage in truss girders or even sudden bridge collapse. Further,the loss of long cables leads to ductile damage with significant displacement.The corrosion in steel truss girders has a highly slight influence on the collapsebehavior of cable-stayed bridge. The proposed methodology can be reliably usedto assess and determine the vulnerability of cable-stayed bridge with steeltruss girders during their service lifetime, thus preventing structural collapsesin this type of bridge.

1300 Tons Grouted Integrity Support Installation Case Study

2020 ◽  
Author(s):  
Beatriz Alonso Castro ◽  
Roland Daly ◽  
Francisco Javier Becerro ◽  
Petter Vabø
Keyword(s):  
North Sea ◽  
Structural Integrity ◽  
High Strength ◽  
Regulatory Compliance ◽  
Lessons Learned ◽  
Oil Field ◽  
The North ◽  
Future Production ◽  
Heavy Lift ◽  
The North Sea

Abstract The North sea Yme oil field was discovered in 1987, production started in 1996 and ceased after 6 years when it was considered no longer profitable to operate. In 2007 a new development was approved, being Yme the first field re-opened in the Norwegian Continental Shelf. The concept selected was a MOPUStor: comprising a jack-up unit grouted to a subsea storage tank. Due to compromised structural integrity and lack of regulatory compliance that came to light shortly after installation, the platform was required to be removed [1]. The remaining riser caisson and the future 1050 t wellhead module required a support to allow the re-use of the facilities and tap the remaining oil reserves. The innovative tubular frame support was designed as a braced unit, secured to the existing MOPUstor leg receptacles and holding a grouted clamp larger than typical offshore clamps for which design guidance in ISO is available. The existing facilities had to be modified to receive the new structure and to guide it in place within the small clearances available. The aim of this paper is to describe the solutions developed to prepare and verify the substructure for installation; to predict the dynamic behavior of a subsea heavy lift operation with small clearances around existing assets (down to 150 mm); and to place large volume high strength grouted connections, exceeding the height and thickness values from any project ever done before. In order to avoid early age degradation of the grout, a 1 mm maximum relative movement requirement was the operation design philosophy. A reliable system to stabilize the caisson, which displacements were up to 150 mm, was developed to meet the criteria during grouting and curing. In the stabilizer system design, as well as the plan for contingencies with divers to restart grouting in the event of a breakdown, the lessons learned from latest wind turbine industry practices and from the first attempt to re-develop the field using grouted connections were incorporated. Currently the substructure is secured to provide the long term integrity of the structure the next 20 years of future production in the North Sea environment.

Background information for some of the proposed earthquake design provisions for the 2005 edition of the National Building Code of Canada

2003 ◽  
Vol 30 (2) ◽  
pp. 279-286 ◽  
Author(s):  
Ronald H DeVall
Keyword(s):  
Structural Design ◽  
Building Code ◽  
Background Information ◽  
Load Path ◽  
Special Design ◽  
Load Paths ◽  
Irregular Structures ◽  
Earthquake Design ◽  
Importance Factor ◽  
Design Requirements

There are many changes proposed for the Earthquake Design Provisions of the 2005 edition of the National Building Code of Canada (NBCC). Among them are requirements for complete load paths, separation of stiff nonstructural elements, and the introduction of definitions of irregular structures and special design requirements associated with these irregularities. A new requirement for direction of loading is introduced, along with requirements for elements common to more than one lateral load resisting system. The effects of displacements are emphasized throughout the document, and revised provisions for drift limits are proposed. Revisions to the importance factor that integrate it into the proposed revised format for Part 4, Structural design, of the NBCC are given. Background information is presented.Key words: load path importance factor, irregular structures, direction of loading, special requirements, drift limits.

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