Experimental fire performance of unloaded stay-cables for bridge infrastructure

2021 ◽  
Author(s):  
Benjamin Nicoletta ◽  
John Gales ◽  
Panagiotis Kotsovinos
Keyword(s):  
Heat Transfer ◽  
Thermal Expansion ◽  
Steel Wire ◽  
Pool Fire ◽  
Image Correlation ◽  
Galvanized Steel ◽  
Fire Performance ◽  
Cable Structure ◽  
Stay Cables ◽  
Resilient Infrastructure

<p>The performance-based fire protection design of cable-supported bridge structures is becoming more common as stakeholders desire more resilient infrastructure. Currently, there exist significant knowledge gaps regarding the fire performance of structural steel cables. The study herein examines the thermal response of several varieties of unloaded steel-stay cables during exposure to a non- standard methanol pool fire. Eight stay-cables varying in configuration (locked and spiral coil), diameter (22,6 mm – 140 mm), and alloy (stainless and galvanized steel) are supported above a 0,6 m x 0,48 m methanol pool fire for duration of approximately 35 minutes. Thermocouples are instrumented at the top, core, and soffit of the cable structure at four different cross-sections to monitor heat transfer during and post-fire. Digital image correlation (DIC) is applied in conjunction with narrow-spectrum illumination to monitor the cable surface without optical interference from flames. Global and individual wire strains are calculated from the DIC analysis to quantify thermal expansion. Temperature data throughout the cable structure presents insight into the heat transfer of steel wire-rope elements. Preliminary results indicate individual wire thermal expansion is similar to that of the global cable structure and that interaction between adjacent wires may limit individual wire expansion. This implies thermal expansion may not be consistent until the cable cross-section is of uniform temperature.</p>

Designing and Validating Parallel Wire Suspension Bridge Wire Strands for Neutron Diffraction Stress Mapping

2017 ◽  
Vol 905 ◽  
pp. 123-130
Author(s):  
Adrian Brügger ◽  
Seung Yub Lee ◽  
İsmail Cevdet Noyan ◽  
Raimondo Betti
Keyword(s):  
Neutron Diffraction ◽  
Steel Wire ◽  
National Laboratory ◽  
Suspension Bridge ◽  
Galvanized Steel ◽  
Element Analysis ◽  
Parallel Wire ◽  
Oak Ridge ◽  
Contact Points ◽  
Suspension Bridge Cables

Suspension-bridge cables are constructed from strands of galvanized steel wire. They are failure-critical structural members, so a fundamental understanding of their mechanics is imminently important in quantifying suspension bridge safety. The load-carrying capabilities of such strands after local wire failures have been the subject of many theoretical studies utilizing analytical equations and finite-element analysis. Little experimental data, however, exists to validate these models.Over the past five years we have developed a methodology for measuring stress/strain transfer within parallel wire strands of suspension bridge cables using neutron diffraction [1,2]. In this paper we describe the design and verification of parallel cable strands used in our studies. We describe the neutron diffraction strain measurements performed on standard 7-wire and expanded 19-wire models in various configurations at both the Los Alamos National Laboratory Spectrometer for Materials Research at Temperature and Stress (LANL SMARTS) and at the Oak Ridge National Laboratory VULCAN Engineering Materials Diffractometer (ORNL VULCAN). Particular attention is placed on the challenges of aligning and measuring multibody systems with high strain gradients at body-to-body contact points.

The York-Arup cable experiments: Implications for the fire design of cable-supported bridges

2021 ◽  
Author(s):  
Benjamin Nicoletta ◽  
John Gales ◽  
Panagiotis Kotsovinos
Keyword(s):  
Thermal Strain ◽  
Experimental Studies ◽  
Thermal Response ◽  
Structural Response ◽  
Fire Performance ◽  
Stay Cable ◽  
Stay Cables ◽  
Bridge Structures ◽  
Recent Trends ◽  
High Level

<p>Recent trends towards performance-based fire designs for complex and critical structures have posed questions about the fire resilience of bridge infrastructure. There are little-to-no code requirements for bridge fire resistance and practitioner guidance on the subject is limited. Research on the fire performance of cable-supported bridge structures is scarce and knowledge gaps persist that inhibit more informed fire protection designs in a variety of bridge types. There have been few numerical or experimental studies that investigate the fire performance of steel stay-cables for use in cable-supported bridges. The thermal response of these members is critical as cable systems are highly dependent on the response of individual members, such as in the case of an anchor cable for example. The study herein examines the thermal response of several varieties of unloaded steel- stay cable during exposure to a non-standard methanol pool fire and the implications for the structural response of a cable-supported bridge. Experimental thermal strain data from fire tests of various stay-cables is used to inform high-level insights for the global response of a cable-supported bridge. Namely, the effects of cable thermal expansion on the overall cable system is approximated.</p>

Natural Convection in an Enclosure With Blend of Micro Encapsulated Phase Change Materials

2013 ◽  
Author(s):  
Yasmin Khakpour ◽  
Jamal Seyed-Yagoobi
Keyword(s):  
Heat Transfer ◽  
Thermal Expansion ◽  
Natural Convection ◽  
Phase Change ◽  
Latent Heat ◽  
Phase Change Materials ◽  
Numerical Study ◽  
Pure Water ◽  
Operating Conditions ◽  
Effective Density

This numerical study investigates the effect of using a blend of micro-encapsulated phase change materials (MEPCMs) on the heat transfer characteristics of a liquid in a rectangular enclosure driven by natural convection. A comparison has been made between the cases of using single component MEPCM slurry and a blend of two-component MEPCM slurry. The natural convection is generated by the temperature difference between two vertical walls of the enclosure maintained at constant temperatures. Each of the two phase change materials store latent heat at a specific range of temperatures. During phase change of the PCM, the effective density of the slurry varies. This results in thermal expansion and hence a buoyancy driven flow. The effects of MEPCM concentration in the slurry and changes in the operating conditions such as the wall temperatures compared to that of pure water have been studied. The MEPCM latent heat and the increased volumetric thermal expansion coefficient during phase change of the MEPCM play a major role in this heat transfer augmentation.

Timber Pole Space Frames

1987 ◽  
Vol 2 (2) ◽  
pp. 77-86 ◽  
Author(s):  
Pieter Huybers
Keyword(s):  
Developing Countries ◽  
The Netherlands ◽  
Double Layer ◽  
Steel Wire ◽  
Galvanized Steel ◽  
Shrinkage Cracks ◽  
Space Frames ◽  
University Of Technology ◽  
Engineering Department ◽  
Under Construction

Timber poles are not often used for structural purposes in building, although they are a cheap material with good mechanical qualities. This is due to the fact that the poles often suffer from shrinkage cracks, which makes it difficult to transfer the load from one element to another in a way that is structurally sound. To overcome this particular problem, in the Civil Engineering Department of the Delft University of Technology a manually operated tool has been developed with which strong and tight lacings of galvanized steel wire can be strung around the poles in order to keep them together. This principle has been applied in spatial-type structures, where larger numbers of identical, relatively thin, poles of 10 cm diameter are interconnected to form double-layer grids. According to this principle a few prototype structures have been built and test-loaded, including the load-bearing frames of two agricultural buildings, one at Lelystad in The Netherlands and one at Winchester in England. A few others are under construction. The tool was originally designed for use in developing countries. For other countries a more industrialized way of producing the laced connections is considered.

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