Review Category : Structural Testing

What is Ultrasonic Testing?

When doctors need to diagnose an internal medical issue, they use an X-ray machine or ultrasonic testing to non-invasively look inside the human body. When it comes to checking the potentially ailing components of a bridge, the engineers can use ultrasonic testing (UT), a non-destructive testing (NDT) method, to look inside the bridge. This allows them to view and understand a bridge’s welds and components for structural integrity before deterioration or internal flaws become a potential hazard.

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Are We Testing for Flow Properties Correctly?

The rheological (flow) properties of concrete are essential for the construction industry, because concrete, for different elements of a structure, is placed into the formwork while it is in its plastic state. The flow properties affect not only proper concrete placement, consolidation, and finishing but also the hardened state properties such as strength and durability. Concrete that is not correctly placed and consolidated may have defects, such as voids and honeycombing, and be prone to aggregate segregation. Improper placement and consolidation may result in reduced compressive strength and increased permeability, reducing the concrete’s durability and sustainability.

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As a general contractor or subcontractor working on a concrete structure, one of the most important tasks is ensuring that the concrete has been properly cured and its quality has been tested according to applicable standards. This is of the utmost importance for quality control and quality assurance purposes. Equally important is selecting an appropriate and accurate method for monitoring the strength of in-place concrete. Unfortunately, popular methods of testing concrete quality, especially compressive strength, are frequently subject to discrepancies.
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The rise in performance-based engineering, in which a structure is proportioned to meet certain predictable performance requirements, necessitates reasonable estimates of component behavior during earthquakes. It is customary to determine component properties via physical lab tests. For components such as concrete anchors, verification of the ultimate strength is required and quasi-static pull tests are sufficient. The situation is more involved for other components, such as beam-to-column assemblies, since an earthquake produces dynamic back-and-forth cyclic actions and the component is often expected to deform inelastically.
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Concrete and masonry members can experience cracking due to their low tensile strength. Cracking can occur for a variety of reasons, including loads, shrinkage, temperature, settlement, or stresses induced by seismic and wind activity. Figure 1 shows diagonal cracks in masonry walls caused by an earthquake. Since cracks can have a significant negative impact on anchor performance, the assumption that an anchor is situated in a crack is not conservative, especially during seismic behavior. For concrete members, building codes require the structural design to address the effects of cracks on post-installed and cast-in-place anchors. Anchors must be evaluated and the structural designer must determine design data. However, for masonry members, there is no provision for considering the impact of cracks on anchor performance. This article presents the results of an experimental program addressing testing and evaluation of anchorage performance in cracked masonry.
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Large Scale Research into Durability of Cross Laminated Timber (CLT) Connections

Moisture management plays an essential role in the serviceability and preservation of buildings, particularly when considering wooden structures. This is because wood’s durability can be compromised by the sustained presence of liquid water, while large moisture fluctuations can also impact dimensional stability and mechanical performance. Like any material, wooden structures perform excellently when designed and maintained properly, with many examples that have stood the test of time and lasted centuries (e.g., the Horyu-ji temple in Japan, stave churches in Norway, etc.). While moisture management principles are generally well understood for light frame construction, there are still many questions to be answered regarding moisture performance of large scale, “mass timber” structures, including how fast they wet and dry and how exposure affects long term durability.

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A Bluffer’s Guide

Wind tunnel testing is a ‘black box’ to many practicing structural engineers. This article strives to shine a small beacon inside the box and provide the reader with a foundation for asking sensible questions of wind tunnel laboratories. It is written from the author’s experience as a practicing wind engineer, an advocate for wind tunnel testing on major projects, and a client in receipt of wind tunnel test reports.

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Determining Existing Masonry Structural Properties

Design professionals rely on numbers. Some of the most important numbers represent the design loads on a structure during an event with a certain probability of occurring, and the resistance of the structure given its geometry, material properties, and connections. In a new structure, these quantities are generally known, specified, and listed on project documents. Design loads are determined by building codes and jurisdiction. Material properties are specified by the designer and verified through testing.

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Evaluating the Seismic Performance of Concrete Elements

Seismic assessment of earthquake-damaged buildings typically involves damage surveys and structural analyses. In this unique project, the evaluations also included the seismic testing of nine full-scale beam-column connections and two portions of shear wall slab connections, extracted from reinforced concrete buildings with minor damage. The concrete specimens had to be tested in less than a year. As the number of specimens and limited time exceeded the capacity of available testing facilities, a local warehouse was turned into a temporary testing facility.

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Non-destructive Testing (NDT) plays a critical role in the understanding of existing structures. Investigative techniques available offer practical, efficient, and cost-effective solutions to obtaining information on quality, construction, and performance that may be otherwise hidden to the naked eye. The use of NDT tools vastly reduces the need for exposing embedded structure through probing, and assists in making more informed decisions when samples or probes must be performed.
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