Journal of Performance of Constructed Facilities

Forum papers are thought-provoking opinion pieces or essays founded in fact, sometimes containing speculation, on a civil engineering topic of general interest and relevance to the readership of the journal. The views expressed in this Forum article do not necessarily reflect the views of ASCE or the Editorial Board of the journal.

Light-gauge cold-formed steel (CFS) is being used more and more as an economical and high performing construction material. In this paper, a numerical study of the seismic performance of an innovative light-gauge cold-formed steel midrise building designed using direct displacement design (DDD) is presented. This new system, termed a uniform truss construction system (UTCS), includes floor trusses, open panels, v-braced panels, columns, and connections between components. A series of reversed-cyclic tests of subassembly structures was conducted to provide the key information to understand the performance of the system under cyclic loading. The test data was then integrated into a numerical model for nonlinear time history analysis. A simplified shear element was developed to represent the panels as well as the floor diaphragm in the numerical model of the system. Nonlinear time history analysis of the building was conducted using a suite of 22 prominent earthquakes recorded from around the world. The results show that the building performs very well compared with the required performance criteria at the global level.

The financial resources available for infrastructure maintenance and rehabilitation are always limited, creating a need for efficient resources management and for the ability to predict maintenance actions throughout the infrastructure service period. In the context of bridges, management systems have been developed and are already implemented around the world. A much larger variety of maintenance problems and a small number of buildings per owner mean that building management systems are still quite rare. Efficient approaches to the management of building maintenance still need to be developed. The first step in a building management system (BdMS) is the collection of data through inspection procedures to detect and measure the defects, and to characterize the building, which is always a time-consuming task. Software solutions were specially developed within a recently developed BdMS to perform accurate and quick inspections of defects on building façades, using essentially the information obtained in a visual and photographic inspection. This paper describes additional software tools, showing how they help building inspection in terms of characterizing and quantifying several anomalies in façades.

Forensic structural engineering plays a critical role in identifying the cause of failure, providing advice in the immediate aftermath of catastrophic failures, and in some cases providing expert opinion in the event of legal disputes. Although many authors have addressed the challenges involved in training the next generation of forensic engineers and further developing the specialty of forensics, this paper examines how the fundamental nature of an engineer’s existing expertise can lead to cognitive entrenchment, and limit an investigator’s ability to respond to failure effectively. The paper argues that an experienced engineer’s design expertise must be substituted with forensic expertise to effectively investigate and respond to failure. The paper concludes by arguing that knowledge of, and experience in, the implementation of the scientific method should become a critical focus for experienced engineers wishing to make the transition to forensic investigation.

High-energy impact rollers (IR) have been increasingly used for earthworks by compacting on-site soils. The IR applies high energy to the ground and densifies deeper soils than conventional rollers and plate-type compactors. A trial program was implemented on the third runway of the Shanghai Pudong International Airport in China to validate the performance of the IR technology. Field monitoring and in-situ testing were undertaken during or after the IR compaction. The cone penetration data indicated that significant improvement in soil properties was measured up to a depth of 4 m after 20 to 25 passes of compaction. However, the improvement of the properties of the very soft silty clay at the depth of 1–2 m was limited. The vibration monitoring data suggested that the IR compaction with 12-t impact module would not cause damage to buildings at a distance of 9.5 m away from the boundary of the compaction path.

This paper describes the load test of a one-way reinforced concrete (RC) slab conducted according to the new ACI 437 load test standard and performed in a three-story apartment building constructed in 1947. The ACI 437 load test protocol and its acceptance criteria are reviewed and discussed. The experimental deflections measured during the load test are compared with the theoretical predictions provided by finite element method (FEM) analysis.

When occupants complain of lively floor motion due to human activity, it is often necessary to estimate the dynamic properties of the floor and ascertain the form and level of vibration response toward the goal of designing an effective retrofit solution. The most detailed and accurate experimental method is to determine the natural vibration modes using full experimental modal analysis, which requires substantial equipment including at least one floor shaker, and then determine the acceleration due to walking. However, due to cost and time constraints and possible unacceptable occupant disruption, it may not be possible to perform a full experimental modal analysis. An alternative testing procedure is to use a handheld spectrum analyzer to record floor accelerations due to heel drop and timed walking excitations. These measurements are then used to estimate the natural frequencies and vibration response level, respectively. This paper describes the procedure and compares results with experimental modal analysis techniques. The method is illustrated by a case study of an in-service floor and is shown to be economical, convenient, and effective.

In bridge engineering, laser-based measurement techniques show promise in assisting field tests due to their noncontact features. A case study of using laser-based remote sensing to help collect data during in situ testing for a bridge finite-element (FE) model validation is reported in this paper. The skewed two-span bridge in this study was constructed with nine high performance steel girders in two phases. A three-dimensional (3D) FE model of the bridge superstructure was developed based on the information provided by the design files. Various field tests were performed to validate the model: (1) light detection and ranging (LiDAR) scanning, (2) static truck load tests, and (3) laser Doppler vibrometer testing. The LiDAR scanner collected geometrical information of the actual bridge. It was also used to measure girder deflections during load testing. The fundamental frequency of the bridge vibration was obtained by using a laser Doppler vibrometer (LDV). In situ dynamic and static measurements were compared to the FE model results, thus offering validation of the analytical predictions. Such analysis of the bridge superstructure serves as a baseline for post construction investigations, with important implications especially for the long-term structural health monitoring of the system as a whole.