Journal of Performance of Constructed Facilities

The condition assessment of existing buildings with special reference to the analysis of degradation level has been extensively and fruitfully applied in the field of maintenance and monitoring. This paper presents a methodology for detecting structural degradation of the building that can be implemented in a decision support system consisting in a platform connected with smart devices. The proposed procedure is suitable for calculating the degradation of the building through a set of key performance indices and an optimized analytic hierarchy process. In addition, the methodology is calibrated through the well-known Tuutti model to consider the damage evolution of reinforcements’ corrosion. The results show that this calibration increases the accuracy of the assessment but reduces the robustness of the method. Moreover, an optimal calibration point is identified by exploiting the results of a set of case studies performed in Italy, Portugal, and Brazil. Finally, the method is compared with a similar approach for the degradation analysis developed in the University of Brasilia.

Customized transport vehicles (CTVs) are usually required to travel along the bridge centerline at low speed. However, emergency situations might occur on the bridge during the passing of a CTV and result in partial closure of the traffic lane. To investigate whether the CTV could pass over multigirder bridges in a manner of lateral eccentric load, five critical CTVs were extracted from long-term recorded data, and the dynamic simulation analysis of 360 different CTV load cases was accomplished. Bending bearing safety assessments of small-to-medium-span multigirder bridges under lateral eccentric CTV loads were conducted and the applicability of specified axle weight limits analyzed by using a load rating method, in which the partial factor of CTV load effect is optimized considering the balance between failure cost and benefit. The results show that when the lateral eccentric distance is not greater than 2.5 m, all safety indices are lower than 0.879 and the bending bearing capacities of multigirder bridges are deemed to meet safety requirements. The safety indices of bridges under fully loaded critical CTVs are lower than 0.977, and the specified CTV axle weight limits are applicable when the lateral eccentric distance reaches 2.5 m. To prevent the structure from entering the plastic stage, the lateral eccentric distances of C-IV and C-V, which denote the fourth and fifth vehicle type, are suggested to be less than 2.0 m when they pass over prestressed T-beam bridges.

An orthotropic steel deck (OSD) has a complicated structure, and its fatigue life is mainly determined by various welding details. Fatigue assessment of deck-to-rib welded joints under long-term train loads is an important concern for engineers. Using the stress range–number of cycles (S-N) curves that are recommended by existing specifications, it is difficult to consider welding residual stress. As a type of initial stress, welding residual stress reduces structural fatigue life by influencing the mean stress of the external cyclic load. However, the effect of mean stress is often overlooked by traditional welding fatigue theory. In this paper, a full-range S-N curve model of steel fatigue resistance integrating welding residual stress is proposed by adopting the Soderberg formula to equivalently transform the stress amplitude and mean stress. The Nanjing Dashengguan Bridge, a six-line railway steel arch bridge and the longest steel arch bridge in the world, is used as an example to demonstrate the fatigue life evaluation procedure of the proposed model in detail. First, the distribution of the welding residual stress of deck-to-rib welded details is obtained based on a refined finite-element model (FEM), and its accuracy is verified experimentally. Second, the partial welded joint model is embedded into the whole multiscale FEM of the steel deck. The structural/real stress spectrum of the welded details under a passenger/freight train is obtained by integrating the coupling effect of the train load stress and residual stress. Finally, fatigue life evaluation of the deck-to-rib welded details of the Dashengguan Bridge is carried out based on the proposed S-N curve model, integrating the residual stress and annual train volume. The results show that (1) the longitudinal residual stress (${\sigma }_Z$) on the top and bottom surfaces of the deck vary with its welding direction respectively (perpendicular or parallel); (2) the maximum value of the real stress under the coupling effect of train load stress and residual stress is less than the yield strength ($f_y$), so the influence of mean stress on the fatigue life of welded joints should still be considered; and (3) the fatigue life calculated by the proposed model is more accurate and conservative than a common standard. In summary, the proposed model provides a basis for determining whether the Dashengguan Bridge can allow freight trains to pass.

For large hydraulic structures such as concrete gravity dams, it is hard to collect the input signal from the bedrock. On behalf of identifying the modal frequency and damping ratio of a concrete gravity dam, the Random Decrement Technique (RDT) with the Hilbert-Huang Transform (HHT) were combined to derive the relationship between the nonlinear nonstationary signal and the modal parameter. This was achieved by the following process: (1) the original signal was filtered using a band pass filter to reflect structural intrinsic vibration characteristics; (2) the multiple intrinsic modal functions were then obtained using Empirical Mode Decomposition (EMD); (3) RDT was used for extracting free attenuation functions from the intrinsic modal functions afterward; and (4) finally, Hilbert Transform (HT) was used to the free attenuation functions, combined with the least squares fitting method, to gain the structure modal frequency and damping ratio. The feasibility of this method was verified using three earthquake acceleration records (2007 and 2008) from the Shuikou concrete gravity dam. For analyzing the accuracy, merits and demerits of this means, our consequences were compared with those obtained using the Peak Point Picking Method (PPP) in the frequency domain, the Autoregressive model with Exogenous (ARX) in the time domain, the Natural Excitation Technique (NExT) united with Hilbert-Huang Transform in the time-frequency domain, and Finite Element Method (FEM). Findings from this study indicate that the proposed approach can be utilized for nonlinear nonstationary signals well.

Various ductile sheet materials are currently being considered to retrofit existing concrete walls to mitigate the effects of external blast. In this paper, the blast mitigation of the soft and rigid sheet retrofit systems of reinforced concrete walls is studied. Different types of thin sheet retrofits, such as steel, rubber, polyurea, and polymer-fiber composite sheets, were examined by using a series of full-scale quasistatic tests to evaluate their static resistance. Finite-element modeling was performed to study the straining action of the wall elements, including the retrofit system. Nonlinear single-degree-of-freedom dynamic analysis was performed to calculate the blast response and study the mitigation effects of the various sheet materials considered. Experimental results showed that all retrofits exhibited significant energy absorption after a support rotation of 10°. Finite-element models were able to closely predict the static resistance function of these retrofitted walls. Parameters such as friction coefficient, end-connection gap due to slack in the sheet, and connection stiffness were investigated. It was found that by increasing the initial gap to account for slack, the membrane action is delayed, which increases the ductility of the wall and the area under the resistance-displacement curve. Increasing the friction and the stiffness of the end-connection increased the resistance and the overall energy absorption of the retrofitted wall system.

This paper presents modal parameter estimation work on a steel railway bridge at three different temperature conditions using ambient vibration test data. The bridge was built at the end of the 19th century using the available technology of its time. It is composed of six spans, each 30 m long, with a total length of 180 m. It is slightly curved in the horizontal plane with a radius of 300 m, and has a vertical grade of 2.5%. Modal parameters of the bridge were estimated using two different output-only system identification methods. The identified results obtained under different temperature conditions were compared in assessing the effects of temperature variation in the identification results. A comparative study in assessing method-to-method and test-to-test variability was also conducted. A three-dimensional finite-element model of the bridge was developed. In order to match the experimentally obtained modal parameters with the numerical ones, a trial-and-error–based model updating study was conducted. This way, a benchmark model of the 199+325 steel railway bridge was obtained for future capacity assessment, prediction, and sensitivity-based model updating work.

A new optimization method for optimal charge scheme calculation is proposed to reduce undesired phenomenon in ring blasting, including brow damage, overcrushing, and bulking yield, which are caused by the unreasonable distribution of blasting energy. First, all the feasible charge schemes are calculated by a traversal algorithm. Then fragment size value is predicted according to the blasting simulation program, which is based on a modified Harries mathematical model. Finally, the optimal charge scheme is selected by the $X_{50}$ and $X_{90}-X_{10}$ of fragment size value of the muck pile. The program is developed by Visual LISP on the AutoCAD platform. A case study illustrates the optimization procedure, and some field tests were conducted in Tonglvshan copper mine and Fankou mine to verify the feasibility of the program. The optimization method can play a positive role in brow protection. It can also obviously improve the muck pile fragment-size distribution.

Fiber Bragg grating (FBG) sensors emerged as a relatively new strain-sensing technology for civil engineering applications. This study presents a field test to assess the feasibility of FBG sensors in monitoring the strain profile of prestressed high-strength concrete (PHC) pipe piles during installation. Two open-ended PHC pipe piles were instrumented with FBG sensors and then driven into the ground using a hydraulic jacking machine. To measure the strain profile along the test piles, nine FBG sensors were arranged in a single optical fiber and then mounted on one pile at the opposite side to monitor the strain at different levels as a function of wavelength shift. The procedure for installing the FBG sensors along the PHC pipe piles is introduced first. Next, the distribution of the axial forces and average side shear stresses that were evaluated from the strain measurements of the FBG sensors are discussed. The field test results indicate that the FBG sensor system was suitable for monitoring the strain state of PHC pipe piles during installation. The axial forces and side shear stresses along the test piles were influenced significantly by the penetration depth and the local soil resistance.

Rapidly aging bridges are a serious problem plaguing the transportation industry. Bridges are subjected to accumulative damage due to environmental effects, traffic, and inappropriate management, which commonly render them structurally deficient over the course of their service life. There are drawbacks inherent to traditional visual inspection methods, including costliness and inefficiency. This paper proposes an innovative damage assessment method based on dynamic fingerprints and data fusion techniques for bridge performance evaluation. Numerical simulation is first applied to obtain dynamic fingerprints under various damage scenarios, then an ambient excitation modal test is conducted to acquire field modal data. Several data fusion techniques are then applied; Bayesian fusion, rough set theory, and Naïve Bayes classifier are combined to make full use of their advantages for convenient and efficient damage evaluation. The proposed method allows for quick detection of the existence, location, and severity of damage for the sake of highly efficient structural condition assessment. Two typical concrete continuous bridges are used to validate the effectiveness of the proposed method. One is a short-span bridge suffering minor damage, and the other is a large-span bridge suffering moderate damage. The results presented here may represent very useful information for the management and maintenance of existing bridges.

The rapid expansion of urban road systems inevitably results in engineering challenges when new road construction requires the safe crossing of existing roads. Therefore, there has been increased interest in box culvert jacking construction and specifically in the novel jacking method of box culvert shield jacking that combines the principles of box jacking and shield tunneling and is a safe approach for underpass projects. In this study, an underpass of a new road running under an existing highway in Zhengzhou, China was constructed using the box culvert shield jacking method. The objectives of the study were to introduce the novel construction and to investigate the development of the settlement characteristics of the existing highway. A numerical analysis was used to establish a three-dimensional numerical model, which was validated by field measurements. The results showed that (1) the novel box jacking method is safe, feasible, and successful; (2) along the jacking direction, the highway settlement gradually decreased from the entrance (south) to the exit (north); (3) during the process of jacking, the settlement behavior of the existing highway underwent three stages, namely slow growth, rapid growth, and a steady stage. A parametric study included investigations of the length of the shield and the lag distance between the central soil and the shield face. These results provide information for similar projects and help to improve box jacking construction.

Occupant behavior has proven significant impact on building performance. The research on carbon emissions has therefore recommended the integration of the technical and behavioral disciplines in order to accurately predict buildings’ carbon emissions. Although various models have been developed that consider the actions of occupants based on quantitative data, few efforts link the impact of occupant behavior to selected energy strategies while also considering the economic, technological, and environmental impacts. This research developed a dynamic model to simulate the interaction of occupant behavior with various energy-efficiency scenarios to reduce carbon emissions. The model will help test the effectiveness of certain energy-efficiency scenarios before implementation. This paper illustrates the structure and the application of the proposed model. The model results show that behavioral change can contribute enormously to carbon emissions reduction even without the installation of more-energy-efficient improvements.

Based on field investigations and model tests on Gouhou concrete-face sand-gravel dam (CFSGD) breach case, a simplified numerical model for CFSGD breach was developed. The two major highlights of the model are the adoption of total-load nonequilibrium transport equation to simulate the erosion process of sand gravels with a wide range of gradation, and the establishment of an analogy to simulate the failure process of each concrete-face slab under various loads during the dam breaching process. The analysis of the case study of Gouhou dam breaching was used to verify the proposed model, and the results showed relative errors of less than $\pm 15\%$ for the output of breach parameters. The sensitivity analysis indicated that the soil erodibility and grain-size distribution significantly affect the prediction of breach flow of the dam.

This paper presents a simplified model to evaluate progressive collapse response of steel beam–column substructures in a midspan column removal scenario. The model accounts for the influence of the span:depth ratio of the beam on progressive collapse behavior of substructures. The model was carefully validated against results obtained from rigorous numerical analyses. A single-story analogy was proposed to derive explicit expressions for progressive collapse–resisting capacity curves based on the energy conservation principle. The expressions covering the full range of loading—including interaction between the bending moments and beam axial load—and problem variables likely to be encountered in practice were derived. These explicit expressions can be applied in a step-by-step manner for tracing nonlinear behavior up to failure.

Debris hazard causes most of the casualties and injuries in terrorist or accidental explosions. It is defined as high-velocity fragments originating from structural components and building envelope systems induced by a blast wave. Unreinforced masonry (URM) walls, which are commonly used as a building envelope system, tend to break into sharp fragments under blast loading, especially when the explosion is at close range. Therefore, it is of great significance to develop effective protective techniques to mitigate the local damage and fragments of URM walls under close-in explosions. In this paper, a new method of utilizing a dry-suspended stone slab system as a protective measure for mitigating local damage to and fragmentation of URM walls under close-in explosions was proposed. The proposed method uses the dry-suspended stone slab system as a blast wave stopper to reduce the blast load acting on the URM wall through the blast wave interaction with the stone slab and blast-induced fragments, thus mitigating the local damage and fragments of URM wall. In order to investigate the effectiveness of the dry-suspended stone slab system, four experiments were carried out to study the local damage and fragments of URM walls protected by the dry-suspended stone slab system and a commercial blast-resistant panel under different close-in blast scenarios. The experimental results were compared with each other and with results of previous tests of unprotected URM walls under the same blast scenarios. The results showed that both the dry-suspended stone slab system and the commercial blast-resistant panel are effective in mitigating local damage to and fragmentation of URM walls under close-in explosions. When the trinitrotoluene (TNT) charge increased from 1 to 6 kg with the standoff distance unchanged (400 mm), the dry-suspended stone slab system performed much better than the commercial blast-resistant panel in decreasing the crushing or spalling damage of the URM wall, indicating that the proposed dry-suspended stone slab system can be used as a protective measure to mitigate the local damage to and fragmentation of URM walls under close-in explosions.

Owing to long building life cycles, facility management (FM) entails a significant responsibility. Furthermore, it is difficult to effectively manage the numerous operation and maintenance (O&M) data generated during the building life cycle, especially for large commercial office buildings. Without this, the facility managers in the operational role cannot achieve a high performance of buildings. However, relatively little research has been conducted on systematic O&M data management processes or methodologies. As a fundamental approach to O&M data management, considerable attention has been given to the analysis on their patterns and trends, specifically based on locational space. The building information modeling (BIM) is a relevant solution for O&M data management that can easily handle data based on locational space. The objective of this study is to develop a practical O&M data management system that employs location-based data analysis. This study has established a data-processing methodology and developed a computerized system using BIM technology. The system allows more accurate cost management and customized O&M work planning and execution, supporting timely decisions for building renovation. As a pioneering work, this study contributes to O&M data management research by establishing an O&M data hierarchy for location-based analysis and by presenting the system’s algorithm and framework. Additionally, the result of this research—a location-based O&M data management system (i.e., LOMDS)—facilitates more accurate and effective O&M data analysis, thereby helping optimize O&M decision making for large commercial office buildings.

The maintenance of heritage buildings can be extremely complex; usually, practitioners face many difficult decisions regarding when and how to intervene. The data recovered over time of the conservation and rehabilitation of heritage buildings could represent a new input to aid stakeholders’ decision-making concerning an efficient planning of the maintenance activities to carried out during the buildings’ service life. This study evaluated the impact of maintenance activities in the functionality of heritage buildings through the analysis of historical records concerning the maintenance activities performed on a set of heritage buildings from the 13th and 14th centuries through the 21st century. A sample of 390 historical records were analyzed, recovered from a set of 20 parish churches in the province of Seville in southern Spain. This study assessed the variations observed in the functional service life (buildings’ performance) of the heritage buildings under analysis according to the different interventions and maintenance actions performed over time. The knowledge of the past behavior of the constructions over time and the impact of the different maintenance activities performed allowed finding some patterns in the data. The results obtained in this study, and the lessons learned from past actions, allow promoting the increase of the stakeholders’ knowledge concerning the impact of maintenance activities in heritage buildings, thus aiding the adoption of more technically informed and sustainable maintenance actions in the future.

The drive toward innovative designs of structural systems assisted by more efficient materials has resulted in ever more slender spans and lighter weight constructions. This has also been accompanied by the growing trend of open-plan floor developments with fewer internal partitions. As a consequence, concerns are being increasingly expressed over excessive human-induced vibrations under normal in-service conditions. These floors might be considered as failing to meet the vibration serviceability criterion, even though in some cases they might satisfy the requirements of existing vibration design guidelines and tolerance limits. Thus, this paper outlines a thorough back analysis of three tested full-scale floors with finite-element modeling to evaluate the reliability of contemporary guidelines. It is demonstrated that current forms of design guidance could require significant improvements in the key aspects of walking load models, response prediction, and threshold tolerance in order to more reliably predict actual vibration response and corresponding vibration assessment.

Field investigations and laboratory tests were performed to determine the cause of engineering distress due to the swelling of lime-stabilized and phosphogypsum-stabilized soil and subsequent cracks on a roadway in China. An exploratory pit was excavated to inspect the damage state. The thickness and water content of the subbase before and after failure were compared. Laboratory compaction and expansion tests were performed to investigate the swelling behavior and the expansion potential of both the mixture from the in-situ subbase and the newly made mixture in the laboratory. It was found that the main reason for heaving in the roadway was due to the overuse of phosphogypsum in mixture of the subbase. In addition, continuous heavy rainfalls were the triggering factor for a series of chemical reactions that occurred among the mixtures in the water-rich surroundings. These combined factors resulted in the failure of the roadway subbase. This work reveals that the dosage of phosphogypsum must be controlled in a reasonable range when it is used in roadway engineering.

Immediately after the 2016 Kumamoto earthquake series, a detailed damage assessment of more than 2,500 wooden houses was conducted at Mashiki Town, Kumamoto. Severe structural and nonstructural components damages were observed for buildings designed after the 2000 building standard law. Results of the field investigation were used to identify vulnerable building type, and in October 2017, a full-scale, two-story, Japanese conventional post and beam wood townhouse was tested under the 2016 Kumamoto earthquake series recorded at the KiK-net station. A triaxial shake table testing facility located in Miki City, Japan, was used. The tested building survived the foreshock and mainshock of the Kumamoto earthquake, and the extent of damage reasonably agreed with the result of the survey around the KiK-net station. Results of the experimental tests will help designers and decision makers to understand the seismic response and damage of the test building and come up with mitigation alternatives.

This paper studies the structural responses and failure modes of a 1.5-MW horizontal-axis wind turbine under strong ground motions and wind loading. Ground motions were selected and scaled to match the two design response spectra given by the seismic code, and wind loads were generated considering tropical cyclone scenarios. Nonlinear dynamic time-history analyses were conducted and structural performances under wind loads as well as short- and long-period ground motions compared. The results show that under strong wind loads the collapse of the wind turbine tower is driven by the formation of a plastic hinge at the lower section of the tower. This area is also critical when the tower is subject to most ground motions. However, some short-period earthquakes trigger the collapse of the middle and upper parts of the tower due to the increased contribution of high-order vibration modes. Although long-period ground motions tend to result in greater structural responses, short-period earthquakes may cause brittle failure modes in which the full plastic hinge develops quickly in regions of the tower with only a moderate energy dissipation capacity. Based on these results, recommendations for future turbine designs are proposed.

Churches are an essential part of the historical and architectural heritage of several countries, and various earthquakes have highlighted the significant seismic vulnerability of ancient religious buildings. On August 24, 2016, a seismic sequence started in Central Italy with a magnitude 6.0 event. Nine events with magnitude ≥ 5.0 occurred between that date and January 18, 2017. Heritage churches were tremendously affected by the sequence, suffering relevant structural and nonstructural damage even far from the epicenters, as in the case of the fourteenth century church of San Francesco in the city of Amandola. The church was inspected several times during the sequence, and a survey was performed using an innovative structure-from-motion digital photogrammetric technique. Ambient vibration tests were carried out on the bell tower before and after the main event of the sequence, and the tower elastic behavior was reproduced by means of a three-dimensional finite-element model. Observed structural performance was interpreted in light of estimated ground motion and literature-obtained models for local mechanisms, with special emphasis on belfry and façade response, and a formula was proposed to account for frictional interlocking between orthogonal walls. Finally, recommendations were developed for troublesome nonstructural deficiencies.

An accident involving the collapse of a running tunnel along Nanjing metro occurred when the tunneling shield arrived at the receiving shaft. Then vertical ground freezing was adopted to recover the collapsed tunnel. However, another water inrush accident happened during the freezing work, leading to a sinkhole of area $15\times 20\mathrm{m}$. This kind of accident that occurred during a recovery process was unusual, so a forensic investigation was conducted. The results showed that a variety of factors contributed to the second accident, including a flawed layout of freezing pipes, position deviation and unreasonable material change of the bulkhead, premature removal of the frozen soil next to the bulkhead, and the absence of thermal insulation measures. These causes can be summarized as the lack of appreciation of the position and extent of the weak area of frozen soil wall at the connection between the collapsed and the intact tunnel. This weak area as well as the possible permeable path were mapped by visual inspection and retrospective analysis of field temperature monitoring data. The lessons learnt from this accident will be helpful to reduce the risk of such accidents in later similar projects for both design and construction sides.

One of the practical difficulties in implementing the structural health monitoring schemes in the field is the challenge involved in detecting the incipient minor damage (subtle cracks) at the earliest possible stage. The minor cracks alter only a few higher modes of vibration in a feeble intensity, which is more difficult to identify and isolate the damage information under the effects of environmental variability and noise in the overall signal. To handle this issue, a novel hybrid baseline-free damage diagnostic algorithm is proposed in this paper, combining an improved version of second-order blind identification (SOBI) with wavelets and time series models. An improved version of SOBI is used to identify and isolate the critical modal responses with damage features. Wavelet analysis on the critical modes identifies the time instant of damage. In a baseline-free framework, the current data is split into reference and damage data segments based on the time instant of damage, and so the environmental conditions are the same for both the segments. Thus, the difficulty of handling the environmental variability does not arise because the temperature variation between any two subsequent data segments is almost nil. The location of damage is identified using the time series analysis of the signal enhanced reconstructed data. Numerical studies and experimental studies are conducted to evaluate the capability of the proposed algorithm in identifying minor/incipient damage like small cracks with noisy measurements.

This paper presents the forensic analysis undertaken on two rehabilitation projects toward highlighting the cost savings achieved by implementing the optimum rehabilitation option and material made from these studies. Without an in-depth understanding of the underlying problem, rehabilitation strategies and materials may result in poor performance at higher construction cost. Conducting forensic analyses can help to better identify the problems before selecting the optimum rehabilitation strategy or material. In other words, engineering judgment based on the result of forensic analyses can be used to make repair recommendations more cost effective while meeting the rising needs of maintenance. In this study, the first project was on the IH20 in the Atlanta district where ground-penetrating radar (GPR) and coring verification were used to determine the presence of deep asphalt patches in the existing pavement. The Atlanta district indicated that it provided a more accurate thickness estimate and reported a savings of $1 million by reducing the extent of milling and using the materials recommended from this study. The main concern in the original design was to mill deeper and use different materials because of the uncertain stripping and damage in the asphalt layers. The second project was on the IH10 in the Odessa district where the rehabilitation strategy proposed in the forensic study called for milling of the top layer only on the inside lane, as opposed to both lanes in the original plan. As a result, the Odessa district reported savings in excess of $1 million by significantly changing their original rehabilitation design options without milling the existing materials and using the recommended strategy and material.

Parallel Seismic (PS) is considered a versatile method capable of determining the specifications of unknown bridge foundations made of common materials such as wood, steel, and reinforced concrete. Although many studies have provided broad information of various theoretical and practical aspects of the Parallel Seismic method, they do not provide information about the performance of this method on short piles and shallow foundations. Challenges and difficulties in determining the depth of such foundations have been discussed in this study. To do so, PS tests were performed on a short pier with four adjacent boreholes and the adverse effect of background noise on the obtained data is discussed as one of the main sources of difficulty. The results of this study showed that the PS testing method does not seem to be a successful method in determining the characteristics of short piers and shallow foundations. This conclusion was supported by results obtained from conducting PS tests on a highway bridge pile.