Acoustic emission (AE) testing was deployed on details of two large steel Interstate Highway bridges: one cantilever through-truss and one trapezoidal box girder bridge. Quantitative measurements of activity levels at known and suspected crack locations were made by monitoring AE under normal service loads (e.g., live traffic and wind). AE...
Scour is by far the primary cause of bridge failures in the United States. Scour and other hydraulic effects are particularly threatening because the deterioration is often invisible, hidden beneath turbid water. Many scour monitoring methods attempt to measure the development of scour pockets themselves. However, this is difficult due...
Kosnik, D. E., Northwestern University . Infrastructure Technology Institute, Department of Civil Environmental Engineering, Robert R. McCormick School of Engineering Applied Science. (2008). A new approach to acoustic emission testing of difficult-to-reach steel bridge details. Evanston, Illinois: Infrastructure Technology Institute/Department of Civil & Environmental Engineering.
This paper describes application of AE monitoring techniques to localize the sources of large noises in civil structures. These noises occur during operation of moveable portions of a structure in such things as lift bridges and moveable sports stadium roofs. The use of straightforward AE monitoring techniques can provide clear...
This paper describes the details of installation and operation of a commercially- available wireless system to measure response of an interior cosmetic crack in a residential structure over a period of a year. Wireless data loggers managed the response of low power draw potentiometers that measured micrometer changes in crack...
This paper describes the technology and methods deployed in the continuous autonomous remote monitoring of cracks in interior and exterior walls of a residence near a limestone quarry. The objective is to quantitatively compare crack response due to blast-induced ground motion to that induced by diurnal temperature changes, weather fronts,...
In this paper vibratory crack response is compared to that produced by volumetric changes in foundation soils induced by natural events. These natural phenomena include changes in the water table, changes in soil moisture, and formation of ice lenses to name a few. Previous papers have compared vibratory responses of...
This paper describes the technology and methods deployed in the continuous autonomous remote monitoring of cracks in interior and exterior walls of a residence near a limestone quarry. The object is to quantitatively compare crack response to blast-induced ground motion to that induced by diurnal temperature changes, weather fronts, and...
Micro-meter dynamic crack responses in a two story structure to rock blasting- and wind gust- excitation are compared to those induced by long term climatological effects. These measurements substantiate the conservancy of the 12.5 mm/s (0.5 in./s) blasting vibration control to protect residential structures against cracking. The test structure was...
A unique judicial opportunity allowed measurement of the response of three cracks in residential structure to blasting for underground aggregate mining. Instrumented cracks were located in the interior basement CMU mortar and upstairs dry wall as well as exterior brick work. The dynamic environment was unusual. Even though the blasting...
Crack and structural response to construction trench blasting was measured in a woodframe house with a stucco exterior. Blasts at distances between 232 m to 368 m produced peak particle velocities (PPV) and air blast over pressures (AB) of 9 mm/sec and 0.02 kPa (123 dB), respectively. Structural response velocities...
This paper describes qualification of devices to measure sub micro-meter changes in crack width, which is the basis of autonomous crack monitoring for control of blasting vibrations. Performance of LVDT, eddy current and potentiometer sensors to monitor long-term and transient displacements will be described. Potentiometers are attractive for wireless measurement,...
This paper describes developments of integrated tools for predicting, monitoring, and controlling ground movements associated with excavations in urban areas. Successful use of monitoring data to update performance predictions of supported excavations depends equally on reasonable numerical simulations of performance, the type of monitoring data used as observations, and the...
Successful use of monitoring data to update performance predictions of supported excavations depends equally on reasonable numerical simulations of performance, the type of monitoring data used as observations, and the inverse analysis techniques used to minimize the difference between predictions and observed performance. This paper summarizes each of these factors...
This paper presents the results of 159 finite element simulations conducted to define the effects of excavation geometry, i.e., length, width and depth of excavation, wall system stiffness, and factor of safety against basal heave on the 3-dimensional ground movements caused by excavation through clays. The results of the analyses...
Several three-dimensional effects were observed in the performance monitoring data collected during excavation for the Ford Engineering Design Center (FEDC) in Evanston, Illinois. These responses are related to lateral deformations of the soil around the excavation walls, forces in the cross-lot and diagonal bracing that supported the temporary wall and...
An empirical procedure for fitting a complementary error function (erfc) to settlement and lateral ground movement data in a direction parallel to an excavation support wall is proposed based on extensive optical survey data obtained around a 12.8 m excavation in Chicago. The maximum ground movement and the height and...
Gentrification - the process in which higher income (and often younger) households displace lower income residents of a city neighborhood - has been occurring in many urban neighborhoods over the last few decades. This process changes the demographics, and often the essential character, of the neighborhood. As a result, we...
The paper deals with the behavior of fluid cement pastes, formulated from Self Consolidating Concretes (SCCs), and the experimental correlation of fundamental rheological properties, such as the yield stress and the viscosity, with measurements from field tests, such as the mini-cone slump flow test. As a matter of fact, several...
In this paper, the correlation of reflection loss measured by an ultrasonic shear wave reflection
method and the microstructure in cement-based material is investigated. Three cement pastes
(Portland cement type I) with different water-cement ratios (0.35, 0.50 and 0.60) cured at 25
°C were examined. The ultrasonic shear wave reflection...