Franklin Moon

In-Plane Behavior of Partially Grouted Reinforced Concrete Masonry Shear Walls

The objectives of this research were to experimentally establish the in-plane behavior of partially grouted (PG) reinforced concrete masonry shear walls and to assess the appropriateness of current seismic design provisions for such walls. To accomplish these, four PG special reinforced masonry shear walls (SRMSWs) were constructed based on the provisions of the Masonry Standards Joint Committee (MSJC) code and subjected to in-plane reversed cyclic displacements. The experimental test variables included mortar formulation, level of axial stress, and boundary conditions. The results of this study indicate that PG masonry shear walls respond similar to in-filled frames and provide little coupling between vertical reinforcing steels. Using these results along with those from past research, it is shown that the shear strength expression for reinforced masonry shear walls provided by MSJC (along with others) appears unconservative for PG masonry shear walls. In terms of displacement ductility, the results indicate that the response of PG SRMSW is consistent with the R factors provided by the 2006 International Building Code due to the required capacity design and increased shear demand provisions of the MSJC.

Experimental Vibration Analysis for Structural Identification of a Long-Span Suspension Bridge

Structural identification (St-Id) of long-span bridges by ambient vibration testing provides a starting point for quantitatively characterizing the actual in-service mechanical characteristics and behaviors of these complex constructed systems. However, various uncertainties involved in the experimental and identification processes impact the reliability of St-Id, especially if vibration testing is the sole experiment. Such uncertainties represent perhaps the most fundamental barrier to more widespread applications of measurements in civil engineering practice. The goal of this paper is to leverage a vibration test of a long-span suspension bridge to illustrate a number of possible strategies for coping with the uncertainties confronted when identifying the dynamic characteristics of large-scale constructed systems. The design and implementation of a field test in the context of St-Id are first presented to illustrate how uncertainties can be mitigated by following a disciplined approach to designing the experiment. Next, data preprocessing strategies including data inspection, time window selection, band-pass filtering, averaging, and windowing are proposed to reduce data errors. Three separate postprocessing methods, including Peak Picking, PolyMAX, and Complex Mode Indicator Function, are executed independently to verify the reliability of the data processing results. Experimental results for both the towers and suspended spans are correlated with simulations from three-dimensional finite-element analysis of the long-span bridge for St-Id.

Temperature-Based Structural Identification of Long-Span Bridges

AbstractTemperature-based structural identification (TBSI) is a quantitative structural evaluation approach that relies on responses resulting from temperature fluctuations. Through this approach, the transfer function that defines how thermal induced strains give rise to global displacements and restrained member forces can be captured. This input-output relationship is highly sensitive to mechanisms that pose modeling challenges, such as boundary and continuity conditions, and thus is quite valuable within the model updating process. The method follows the traditional structural identification (St-Id) framework with a priori modeling, experimentation, and model calibration steps appropriately modified to allow for the measurement and simulation of temperature-induced responses. TBSI was evaluated through the use of simulations and laboratory experiments and then implemented to identify an arch bridge. In addition, a comparative study was performed with an independent evaluation of the same bridge using ...

A data fusion approach for progressive damage quantification in reinforced concrete masonry walls

This paper presents a data fusion approach based on digital image correlation (DIC) and acoustic emission (AE) to detect, monitor and quantify progressive damage development in reinforced concrete masonry walls (CMW) with varying types of reinforcements. CMW were tested to evaluate their structural behavior under cyclic loading. The combination of DIC with AE provided a framework for the cross-correlation of full field strain maps on the surface of CMW with volume-inspecting acoustic activity. AE allowed in situ monitoring of damage progression which was correlated with the DIC through quantification of strain concentrations and by tracking crack evolution, visually verified. The presented results further demonstrate the relationships between the onset and development of cracking with changes in energy dissipation at each loading cycle, measured principal strains and computed AE energy, providing a promising paradigm for structural health monitoring applications on full-scale concrete masonry buildings.

Governing issues and alternate resolutions for a highway transportation agency's transition to asset management

Whether the increasingly poor performance of transportation infrastructure, the budget shortfalls many owners are facing, or the increased demand for more accountability are considered, it is clear that a revolution related to the management of transportation infrastructure is long overdue. There is a broad consensus that this revolution will take shape through adapting and transitioning to the paradigm of asset management (AM). This paper firstly reviews the concept of AM applied to transportation infrastructure, identifies key attributes, and provides a brief overview of the on-going and planned transition to AM by two transportation agencies. Secondly, this paper provides an overview of the related paradigms of performance-based engineering, lifecycle cost analysis, and structural health monitoring, and their role within an integrated AM system. Finally, this paper identifies and discusses relevant issues that transportation infrastructure owners face when they embark on a transition to AM, and proposes an outline for a roadmap to guide this transition.

Advanced Visualization and Accessibility to Heterogeneous Monitoring Data

The proper management and visualization of data is crucial for the success of structural health monitoring (SHM). The article discusses how SHM is a promising tool for the better management of infrastructure. General principles for SHM data management are researched, established, and proposed by the authors, and an original solution for data management based on these principles is presented. The article discusses how data management is especially challenging when heterogeneous data are involved and combined with camera images. Various sensors based on different technologies can measure many parameters such as strain, tilt, weather, etc., whereas live cameras can visualize traffic response and all of the data streams can be registered both statically and dynamically. Data management is even more complex if multiple users access the data and have diverse backgrounds and interests (e.g., the owner/manager of the structure, operator, responsible engineer, and academic). The proposed principles were implemented in novel data management software and applied to a signature bridge for validation purposes. The article discusses how feedback from interested groups including managers, operators, engineers of record, and academics are used for validation.

Mitigating Epistemic Uncertainty in Structural Identification: Case Study for a Long-Span Steel Arch Bridge

Characterization of constructed civil-engineering systems through structural identification (St-Id) has gained increasing attention in recent years due to its potential to enable more effective infrastructure asset management and performance-based engineering. Although there have been recent advances that mitigate the challenges posed by aleatory (random) uncertainty, there are many remaining challenges associated with epistemic (bias) uncertainty that often have a more critical impact on the reliability of St-Id (especially with applications to constructed systems). The objective of this paper is to illustrate various sources of epistemic uncertainty and describe mitigation approaches by detailing the St-Id of a long-span steel arch bridge. This application includes a priori modeling, ambient vibration monitoring, data processing, feature extraction, and finite-element (FE) model correlation. Following a description of the St-Id, the impact of various modeling uncertainties on the calibrated FE model is ...

A new impact testing method for efficient structural flexibility identification

Traditional multi-reference impact testing (MRIT) has the merit of identifying not only the structural modal parameters but also structural flexibility. However, it requires a large number of sensors mounted on the entire structure which leads to expensive experimental costs. A new mobile impact testing method is proposed in this paper for a more efficient flexibility identification of bridges. In the proposed method, the structure under investigation is subdivided into smaller sub-structures which are tested independently. Then the experimental data collected from all sub-structures are integrated by taking the interface measurement as a reference for flexibility identification of the entire structure. The new impact testing method only requires limited instrumentation, thus it can be performed rapidly and efficiently. In particular, the signal processing procedure developed in the proposed method is able to identify the full flexibility matrix of the entire structure from the sparse FRF matrices of the sub-structures. Numerical and experimental examples studied successfully verify the effectiveness of the proposed method by comparing its results with those from the traditional MRIT method for structural flexibility identification and deflection prediction. (Some figures may appear in colour only in the online journal)

Impacts of Epistemic Uncertainty in Operational Modal Analysis

AbstractField experimentation on constructed systems demands consideration of many mechanisms of epistemic and aleatory uncertainties as well as human errors and subjectivity. This is especially true in operational modal analysis (OMA) applications that aim to identify the dynamic properties of a structure. Although statistics and probability theory are sufficient for quantifying aleatory uncertainty and bounding the resulting errors in OMA results, there is much debate as to whether the same tools may also be used to quantify epistemic uncertainty. This study explored a framework for better understanding the distinctions and impacts of these two types of uncertainties in OMA and how human errors and subjectivity may be classified. A physical laboratory model was designed to simulate four key sources of epistemic uncertainty that represented the primary test variables: structural complexity (changing boundary conditions, nonlinearity), ambient excitation characteristics (magnitude, directionality, and ban...

Special Issue on Real-World Applications of Structural Identification and Health Monitoring Methodologies

Although the importance of civil infrastructure is universally recognized, the funding to maintain the U.S. system has proven insufficient over the last several decades. As has been reported recently by ASCE, an estimated