Journal of Performance of Constructed Facilities

The rate of corrosion of the reinforcing bars is one of the important parameters required to estimate the residual service-life of a reinforced concrete (RC) bridge deck. In the present study, first, the linear polarization resistance technique was used to measure the corrosion rates of plain mild steel and cold twisted deformed (CTD) bar specimens, which were typically used in the older existing bridges. To consider the variability of a corrosion rate, the frequency distributions of the corrosion rates for the two types of bars were determined. Next, a probabilistic approach was adopted for assessing an existing RC girder-and-slab road bridge deck, subjected to corrosion of bars attributable to air-borne chlorides. A computational model was developed using the Monte Carlo simulation method, to assess the reduction in the flexural capacity of a typical girder. It was observed that the reduction in the mean capacity and the dispersion of the capacity with respect to time, were high with the measured statistical parameters of the corrosion rate of CTD bars.

Structural failures occur worldwide. Various investigations have concluded that the primary causes of failure were design and construction errors within the building process. However, the exact factors that played a significant role were not clear. Therefore, the primary focus of this study is to improve structural safety by determining the influencing factors for structural safety within the design and construction process. First, a theoretical framework was developed, based on safety science and management literature. In particular, the concept of critical success factors, the factors within projects that are essential to reach the stated goals, appeared to be useful for this research. The factors mentioned in the literature played a role within some documented structural failures in the Netherlands. Based on this framework, a questionnaire was established. In this questionnaire, participants from the building industry were asked to indicate the extent to which factors from the theoretical framework were present in successful and less successful projects. In addition, they were asked to select the greatest determining factors for structural safety, in their opinion, from a list of possible factors. The results were statistically analyzed. Factors concerning the interrelations between various project partners had the largest impact on structural safety: communication and collaboration, control mechanisms, allocation of responsibilities, structural risk management, safety culture, and knowledge infrastructure. These factors will be designated the critical factors for structural safety, which are essential to assure structural safety within projects.

Because most of the research conducted in the area of blast-resistant and retrofit designs of cold-formed steel studs has focused on high threat levels, a need exists to examine moderate blast level protection. The main objective of this paper is to evaluate and upgrade the capacities of conventionally connected cold-formed steel stud-track systems for blast-resistant design. This objective was achieved by performing quasi-static experiments on full-length (3 m) wall samples to investigate the effect of stud and track gauges, screw sizes, and screws layout on the resistance of the wall. A numerical model was developed and verified using the experimental results. Because the model showed excellent agreement with the experimental results, it was used to perform a series of simulation tests. The finite-element model, along with a failure criterion that was developed to predict the failure point of the simulated tests, provided an economical alternative way to investigate the resistance. Valuable recommendations to enhance the resistance behavior of conventional stud-track wall systems are provided.

The New Galata Bridge connects the two sides of the entrance of the Golden Horn in Istanbul city of Turkey and as a bascule-type bridge, has four flaps, each having a span of 42 m. The bridge has replaced the original Galata Bridge, which gave service from 1912 to 1985. After the new bridge was constructed, serious cracks in steel stringers and near the counterweight blocks were observed during maintenance. As a result, modifications around these areas were made. In this study, fracture and fatigue analyses for cracks occurred in the original structural system were performed. For this purpose, a three-dimensional (3D) finite-element model of the third flap was prepared. Detailed computer analyses were carried out based on original drawings. The stress intensity factor values for cracks were evaluated by using 3D finite-element models and submodels of the bridge. To describe the notch toughness of the material in the vicinity of the cracks, a series of Charpy V-notch (CVN) tests were conducted. The results of the finite-element analyses were compared with the experimental evaluation results. The cracked locations of the bridge were clearly observed in computer model results. Based on these results, recommendations were provided.

Deformation and expansion joint movement of bridges are among the problems that widely exist in bridge engineering practice. Therefore, it is very important to monitor deformation of bridges and to timely process and analyze the measured data to ensure their safety. Mansoura Bridge, located at El-Mansoura City in Egypt, is selected to demonstrate the utilization of bridge deck deformation monitoring data to analyze and evaluate its safety based on global positioning system (GPS) measurements. The wavelet principal component analysis (WPCA) and spectrum methods are used to establish the time and frequency domain of bridge deformation and analyze the behavior and movement of the bridge under working traffic loads. The following conclusions are obtained in this study: (1) the WPCA can be used to eliminate the GPS observation errors; (2) the three-dimension spectrum gives much richer information for dynamic response; and (3) the deformation and expansion joint movement of Mansoura Bridge are safe under current loads.

A clock tower in St. Albert, Alberta, Canada, was outfitted with a remote monitoring system to record the vertical deformations of its masonry cavity wall enclosures due to temperature and moisture changes. Monitoring the deformations of masonry wall enclosures is a unique application that is expected to provide new information on the causes of distress of brick veneers, which has traditionally been attributed to excessive expansion of the brick. Preliminary observations for clay brick veneer masonry suggest that reversible moisture-related strains could be significant and that radiation-induced temperature spikes could be much higher than what is accounted for by current design standards and codes. Most observed reversible moisture-induced strains were within the limits prescribed in the Canadian masonry standard and the national building code of Canada.

This paper follows the development of an inspection and diagnosis system for the external cladding of pitched roofs (ECPR) and shows the results of that study with respect to the design stage. It mainly focuses on how errors associated with the design stage influence the durability of ECPR and, consequently, the service life of buildings. Design errors are a constant feature in ECPRs and a statistical-based approach founded in a significant sample was felt to be the best way to fill the remaining gaps in the knowledge of this specific area, because there are no similar studies on pitched roofs in the literature. Therefore, the pathological situation, the diagnosis methods and the repair options of pitched roofs are characterized for the first time in terms of the influence of the design of pitched roofs through quantitative indicators and for eight different types of claddings. Only an improvement of the quality of design plans of ECPRs can lead to a significant decrease of their anomalies and to a maximization of their service life.

The current number of deficient U.S. bridges makes the evaluation of bridge condition paramount to a state highway department in developing a bridge management system. State DOTs routinely visually inspect bridges on 24-month cycles. Findings from these inspections are numerically summarized by bridge inspectors for bridge condition ratings and additionally documented with inspector notes and pictures. However, bridge inspections include a human factor, which introduces bias and subjectivity. Consequently, bridge inspection values are tainted with nonuniformity. This article presents gigapixel technology as an inexpensive quality assurance/quality control tool that can easily be implemented by a state DOT for their bridge inspections. The process includes developing gigapixel panoramas of a bridge that can later be reviewed by bridge engineers trained for this task. The proposed approach is used to supplement visual bridge inspection to improve quality control among bridge inspections. This approach promotes uniformity between bridge sites by reviewing multiple bridges by the same group of engineers; the methodology streamlines the documentation included in bridge inspections. In addition to bridge inspections, the technology has the potential for use in a health monitoring program through cataloging images and/or developing time-lapse videos as a culmination of multiple panoramic images.

The Beaver Creek Bridge on U.S. Highway 6 is a single-span bridge and a pilot project for glass fiber–reinforced polymer (GFRP) precast bridge decks in Utah using accelerated bridge construction (ABC). The Utah Department of Transportation decided to evaluate GFRP bars as an alternative to steel bars for reinforcing the bridge deck. The precast concrete panels were 12.62-m long, 2.08-m wide, and 235-mm thick and were reinforced entirely with GFRP bars. The bridge deck panels were lifted from the underside at four points using steel cables inside steel tubes or nylon straps instead of embedded steel anchors. Two of the 24 panels used to construct the bridge deck were instrumented with strain gauges. Experimental strain measurements showed that the panels exhibited acceptable levels of strain that were below concrete cracking limits. By comparison, similar laboratory panels with identical thickness and reinforcement that were lifted with four embedded anchors from the panel top experienced cracks on the underside of the panels. A finite element model confirmed the experimental results by predicting that the bridge deck panels would not crack during four-point lifting from the underside.

Calcium carbonate deposits are known to clog tunnel drainage systems and clogging is a major concern to tunnel operators worldwide. After analyzing several industrial solutions for treating calcium carbonate, experiments were conducted to evaluate the use of substrate modification and magnetic fields in inhibiting calcium carbonate deposition. For substrate modification tests, laboratory experiments showed the least amount of deposits on polytetrafluoroethylene and polydimethylsiloxane coatings, while polyvinyl chloride (PVC) pipes showed the most. Simulated tunnel drainage test results showed PVC pipes inclined at large gradients and PVC pipes with installed magnets to have slightly less calcite deposits than PVC pipes without magnets. The amount of deposits suggested the influence of magnetic fields to be minor and secondary relative to water velocity.

As a result of previous laboratory tests suggesting an effect of magnetic fields on the deposition of calcium carbonate, tunnel operators in Seoul, South Korea, assigned three tunnel sites, Namsan #3 tunnel and subway tunnel segments near stations 750 and 542, to evaluate the effectiveness of magnetic fields in inhibiting calcium carbonate deposition. Field tests conducted over several months revealed no significant effect from the use of magnets. Observations from one site suggested the use of magnets to be a clogging hazard, as iron compounds would assemble around the magnet. From these results, the application of magnetic fields to inhibit calcium carbonate deposition in tunnel drainage systems is not recommended.

Collapse of a 15.7-m-deep excavation in very sensitive organic soft clay in Hangzhou, China, is presented in this paper. The collapse of the excavation caused the break and/or inclination of the retaining walls, the wracking of the supporting system, significant sinking of a major road adjacent to the excavation site, and also the break in a water main beneath the road. After the collapse, the ground disturbance due to the collapse was investigated by cone penetration tests (CPTs) and field vane shear tests (VSTs). A simplified method, based on the CPT and VST test results, was used to evaluate the strength reduction ratio (SRR) of the in situ soils. According to the SRR values of the soils at different depths, the lower boundaries of the severely disturbed soils were determined and a possible slip failure surface passing through the bottom of the severely disturbed soils was justified. The factors of safety (FOSs) against basal heave of the excavation calculated from various methods were 1.05, 0.74 and 0.89, respectively. These computed values were much smaller than the corresponding recommended values. The stability number $N$ of the excavation was calculated to be 7.4. The overall FOS was studied using the shear strength reduction technique based on a finite-element method (FEM) program. The FEM analysis results indicated that the FOS of the excavation was 0.97, and the computed slip failure surface fit well with that from the soil disturbance investigation. The failure mechanism of the excavation was then justified to be a basal heave. The main reasons leading to the collapse and lessons learned from the collapse are discussed. The investigation of the failure provides experiences and lessons for deep excavation design in very sensitive organic soft clay.

Bridge failure as a result of scour may cause a serious disaster because it tends to occur suddenly and without prior warning. Although the scour depth around a bridge pier is an important index to evaluate the condition of the bridge, it is difficult to measure directly because the bridge foundation is under water. In addition, the safety level of the bridge could be arbitrary, depending on the environment and bridge. In this study, an approach that combines a finite-element simulation and support vector machine (SVM) is used to determine the scour safety level of a bridge through the variation in the natural frequency of the bridge structure. A series of finite-element simulations is implemented with different environmental scenarios to obtain bridge natural frequencies. Moreover, SVM is used to classify the data and provide a safety level for a bridge scour prewarning. At the same time, a five-fold cross-validation and two-step grid search technique are introduced to optimize the SVM parameters. Finally, the examination results are presented that show the high performance of the SVM classification.

A regional bridge failure database was used to determine the bridge failure rate with associated causes. Using a sample population from one DOT over a 25-year period, the average number of bridge failures was approximately $1/\mathrm{4,700}$ annually with a 95% confidence interval from $1/\mathrm{6,900}$ to $1/\mathrm{2,700}$ annually. The number of bridge failures per year was modeled with a geometric distribution that requires a constant failure rate. Based on a validation analysis with bridge failures from six separate DOTs, other DOTs have bridge failure rates within the determined sample population 95% confidence interval. Analysis of the failed bridges by year of construction shows no apparent era of construction that is more susceptible than another to failure. Correspondingly, the determined constant failure rate ascertained in the model selection indicates that the changes in bridge design specifications and maintenance regulations do not appear to have significantly reduced bridge failure rates. Based on the data extrapolation, the estimated average annual bridge failure rate in the United States is between 87 and 222 with an expected value of 128.

A new, practical mechanical prestressing system was developed to prestress carbon-fiber-reinforced polymer (CFRP) sheets. The system is used for strengthening reinforced concrete members. The main features of the system are as follows: (1) the prestressing forces are applied manually without using hydraulic jacks, (2) the prestressing level of the CFRP sheets can be controlled by using an electronic load cell, (3) the system is light weight and can be installed without using heavy lifting equipment, (4) the CFRP sheets are extended to the ends of the member where high shear stresses occur, and (5) releasing of the prestressing CFRP sheets is accomplished under a slow strain rate. An experimental program was conducted to check the validity and efficiency of the prestressing system by testing three reinforced concrete beams. One of these beams was used as a control beam, whereas the others were strengthened with prestressed CFRP sheets. Results show that the system is efficient and practical for prestressing CFRP sheets to strengthen reinforced concrete beams. The cracking and yielding loads increased with an increase in the prestressing level.

The majority of operation and maintenance challenges in building projects are attributed to the decisions made during the design phase. The timely involvement of the maintenance team in the design development and review stages provides a potential for reducing maintainability problems during the functional life of buildings. This paper identifies and assesses the significant water supply and drainage systems’ design defects that commonly occur in the building projects in Saudi Arabia as a consequence of the lack of maintenance feedback to the design team. These defects were identified based on knowledge from the published literature and professional practice. The research reported in this paper endorsed the importance of all the recognized defects based on the appraisal of the executives of the campus maintenance departments in the 13 public Saudi Arabian universities renowned for operating and maintaining substantial building stock. The paper then presents a series of validated maintainability design review checklists by the survey participants, derived to reduce the occurrence of the identified defects. These checklists are available for consideration by design professionals at two main design completion stages, i.e., (1) 60%, and (2) 90%. This paper is of practical value to design professionals aiming to design maintainable building projects, and maintenance managers striving to provide the most efficient level of service to occupants and property owners.

Tongue-and-groove plank wood decking is a product that is commonly used in post and beam timber construction to transfer gravity loads on roofs and floors. Little research or development has been done on plank decking since the 1950s and 1960s. An experimental program was undertaken at the University of Ottawa’s structural laboratory to better understand the behavior of plank decking under concentrated loads. Destructive tests were conducted on plank decking systems to investigate their failure mode characteristics and to quantify their capacity. The failure mode of a decking system under a concentrated load was consistent with a combination of failure in the decking boards and the tongue-and-groove joints. Significant load sharing was observed for plank decking under concentrated loads and it was found that the assumption of basing the design capacity on that of one board was invalid. Placing sheathing on top of a decking system to create a diaphragm action had a very significant and positive effect on both the stiffness and ultimate capacity of the decking system, which currently is ignored in design. The increase in stiffness and capacity can be attributed to the sheathing aiding in distributing the concentrated load to the unloaded decking elements and preventing the failure of the tongue-and-groove joints.

This paper uses finite-element techniques to investigate the performance of buried tunnels subjected to surface blasts incorporating fully coupled fluid-structure interaction and appropriate material models that simulate strain-rate effects. Modeling techniques are first validated against existing experimental results and then used to treat the blast-induced shock-wave propagation and tunnel response in dry and saturated sands. Results show that the tunnel buried in saturated sand responds earlier than that in dry sand. Tunnel deformations decrease with distance from the explosive in both sands, as expected. In the vicinity of the explosive, the tunnel buried in saturated sand suffered permanent deformation in both axial and circumferential directions, whereas the tunnel buried in dry sand recovered from most of the axial deformation. Overall, response of the tunnel in saturated sand is more severe for a given blast event and shows the detrimental effect of pore water on the blast response of buried tunnels. The validated modeling techniques developed in this paper can be used to investigate the blast response of tunnels buried in dry and saturated sands.

Cable replacement is one of the key technologies used in the successful operation and maintenance of cable-stayed bridges. Removing cables causes structural variations. Selecting a replacement method affects bridge safety during the cable replacement process. A sensitivity analysis was applied to assess the variations of force and deflection in the Sutong Bridge, China. Reasonable methods for both the quantity and position of replacing cables were provided; the bending strain energy changes induced by the cable removal were also analyzed to study the effects of different cable replacement sequences. Comparison of different cable removal schemes showed that both the induced cable force and beam stress change had their most significant influence on the nearest cables to those removed ones. Practically, the largest peak value of cable force increment appeared when removing the shortest cables. The peak value was practically identical with little apparent variation when removing one cable in the central span. The largest beam stress variation arose because of the longest cables (or their nearest neighbors) being removed. The maximum deflection of the tower top had a decreased tendency when the removed cable became short. The bending strain energy also decreased in a similar fashion. Based on the analysis results, replacing one cable from the side span and replacing four cables asymmetrically was recommended, and a replacement sequence running from the shortest cable to longest cable proved to be optimal.

The main goal of this study is to use the factor method to evaluate the service life of ceramic external cladding. An interesting possibility is that a tool may be developed to aid the planning of maintenance operations, to reduce costs, and to ensure a better performance of the cladding system. The method relies on field work data on the state of repair of the façades, based on a survey of 195 façades in the Lisbon area. The factors affecting durability are singled out and quantified through several scenarios with the aim of optimizing the weighting coefficients. The degradation model has provided consistent results for most of the variables influencing the cladding’s loss of performance. Adequate knowledge on the durability of a component allows correctly designing the details and planning the maintenance operations that the component requires. These in turn are part of a broader perspective that involves reductions in costs and environmental impact, exactly the challenges that service life prediction proposes to overcome.

Existing research on progressive collapse of building structures mainly focuses on concrete and steel frame structures. To investigate the progressive collapse resistance of high-rise RC frame shear wall structures, two typical 15-story building models are designed with equivalent overall lateral resistance to seismic actions. However, the structural layouts in resisting the lateral forces are quite different for the two buildings. Building A is a weak wall-strong frame structure, whereas building B is a strong wall-weak frame system. Three-dimensional (3D) finite-element models of the two structures are established using fiber beam and multilayer shell elements. The progressive collapse resistances of the frames and the shear walls in both structures are evaluated under various column (shear wall) removal scenarios. Results demonstrate that there is a difference in progressive collapse prevention performance for different structural layouts. The progressive collapse resistance tends to be inadequate for the strong wall-weak frame system. Such a system is subsequently redesigned using the linear static alternate path (AP) method proposed in GSA guideline, through which the reliability and efficiency of the method are confirmed. The outcome of this study has provided a reference for progressive collapse prevention designs of typical and representative high-rise RC frame shear wall structures.

Aftershock ground motions are essential for the study of aftershock synthesis into seismic risk. However, the number of available aftershock records is limited, which necessitates that the methods for synthesizing aftershocks to be developed. This paper aims to propose a methodology to synthesize aftershocks based on the information of the mainshocks, which is able to incorporate the uncertainties of ground motions and can be utilized in seismic risk analysis. The proposed method is illustrated by application to risk analysis for two nonductile RC frame buildings and is validated by comparing with the results obtained from using as-recorded mainshock-aftershock (MS-AS) sequences. The results calculated when only mainshocks are considered are also studied to investigate the MS-AS effects. The paper shows that the synthesized MS-AS sequences using the proposed method can yield results statistically close to the as-recorded sequences. The results also reveal that only considering the mainshock will underestimate the seismic risk but the underestimation is limited.

A bridge-deterioration approach is to predict the condition ratings and the deterioration pattern of bridge elements for determining optimal maintenance strategies and estimating future funding requirements. To effectively predict long-term bridge performance, an advanced integrated deterioration approach has been developed that incorporates a time-based model, a state-based model with the Elman neural network (ENN) and a backward prediction model (BPM). The proposed approach involves the categorization of the selected inspection records by bridge components, material types, traffic volume, and the construction era. The primary advantage of such categorization is to group similar components together, thereby identifying the common deterioration patterns. A selection process embedded in the proposed approach offers the ability to automatically select the most appropriate model for predicting future bridge condition ratings. To demonstrate the advantage of the proposed approach in predicting long-term bridge performances, case studies are performed using available inspection records. To compare the performance of the proposed approach against the standard Markovian-based deterioration procedure in predicting future bridge condition ratings, a total of 40 bridges with 464 bridge substructure inspection records are selected and used as input. The predicted outcomes are validated by a cross-validation process, which demonstrates that the proposed approach is more accurate than the standard Markovian-based procedure.

The side-by-side box-beam bridge is the bridge of choice for short to medium span bridges due to ease of construction, favorable span-to-depth ratios, aesthetic appeal, and high torsional stiffness. The bridge can be constructed in an accelerated fashion, and classified among the systems that qualify accelerated bridge construction (ABC). This bridge is losing favor primarily because of persisting performance issues such as cracking between the beams that reflects to the deck surface. This is in spite of design changes, primarily for resolving the performance issues, since the 1950s. However, performance problems, specifically the longitudinal deck cracking reflecting from the shear keys, still persists. Reflective deck cracking is identified as the leading cause for triggering other distresses that create safety concerns. Significant recommendations in literature to mitigate reflective cracking include: (1) using full-depth grouted shear keys and transverse posttensioning, and (2) incorporating a cast-in-place concrete deck and seven-day moist curing of the deck. The most recent design in Michigan incorporates all these recommendations. Hence, the evolving Michigan Department of Transportation (MDOT) side-by-side box-beam bridge superstructure design procedure was examined, and major design changes were identified. In evaluating the impact of changing design details, numerous in-service bridges were inspected. The list of inspected bridges includes a representative age sample of 15 in-service bridges, a replacement bridge prior to traffic loading, and a demolition project. The distress types, states, and progression were documented from the inspection of in-service bridges. Unfortunately, with full-depth shear keys, high levels of transverse posttensioning, and a 150 mm (6 in.) thick seven-day moist cured cast-in-place concrete deck, Michigan still experiences reflective longitudinal deck cracking. Inspection of a bridge under construction showed that the grout-beam interface cracking develops within a couple of days after grouting and the deck cracking well before the bridge is opened to traffic. The synthesis of all data yielded that the design changes failed to mitigate longitudinal cracking on side-by-side box-beam bridges. The motivation of this article is twofold: first is to analyze and identify the reasons for the reflective cracking. The second motivation is the scientific curiosity of solving a problem that has troubled the bridge engineers for over 60 years.