Accurate thermal properties are crucial for modeling the response of infrastructure to fire scenarios. While other researchers have contributed significant effort toward characterizing the thermal behavior of parallel-wire structural cable stays, no method has been derived explicitly for suspension bridge main cables, which are typically two orders of magnitude larger in cross section. These cables cannot be treated as monolithic steel sections due to the nature of their composition, and their thermal behavior is greatly influenced by voids and point contacts between their constituent cylindrical wires. This study derives the first empirically driven estimation of the effective bulk thermal conductivity of suspension bridge main cables using the data collected from thermal experimentation on a full-scale mock-up of the main cable panel (approximately 10,000 wires, 52 cm diameter, 6 m long) and gradient-based optimization of a representative finite-element model. Results show that the effective thermal conductivity of suspension bridge main cables is more than an order of magnitude smaller in the radial direction than in the axial direction and that the effective radial conductivity is an order of magnitude smaller than previous theoretical estimates have predicted. The resulting bulk conductivity serves as a useful tool for engineers and researchers because it allows a large, thermally complex geometry to be modeled as a simple monolith with orthotropic thermal conductivity properties.

The Oak Ridge National Laboratory is planning to build the Second Target Station (STS) at the Spallation Neutron Source (SNS). STS will host a suite of novel instruments that complement the First Target Station’s beamline capabilities by offering an increased flux for cold neutrons and a broader wavelength bandwidth. A novel neutron imaging beamline, named the Complex, Unique, and Powerful Imaging Instrument for Dynamics (CUPI2D), is among the first eight instruments that will be commissioned at STS as part of the construction project. CUPI2D is designed for a broad range of neutron imaging scientific applications, such as energy storage and conversion (batteries and fuel cells), materials science and engineering (additive manufacturing, superalloys, and archaeometry), nuclear materials (novel cladding materials, nuclear fuel, and moderators), cementitious materials, biology/medical/dental applications (regenerative medicine and cancer), and life sciences (plant–soil interactions and nutrient dynamics). The innovation of this instrument lies in the utilization of a high flux of wavelength-separated cold neutrons to perform real time in situ neutron grating interferometry and Bragg edge imaging—with a wavelength resolution of δλ/λ ≈ 0.3%—simultaneously when required, across a broad range of length and time scales. This manuscript briefly describes the science enabled at CUPI2D based on its unique capabilities. The preliminary beamline performance, a design concept, and future development requirements are also presented.