Journal of Performance of Constructed Facilities

To obtain the failure mode and damage mechanism of a RC box girder under internal blast loads, the dynamic response process of the RC box girder under internal blast loads was carried out in an experiment and numerical simulation. The results show that after the blast, the failure morphology of the numerical simulation was in good agreement with that of the experiment. The front-face surface of the top slab was damaged by a compressive wave, and the back-face surface was damaged by a tensile wave. There were obvious transverse cracks at the joint between the web and the top slab (bottom slab), and there were many vertical cracks in the web. A large area of penetrating damage occurred in the center of the bottom slab.

Large-span spatial steel structures are subject to complex stress conditions during construction, especially during the unloading phase, and they are easily affected by the environment and the loading method. Therefore, it is necessary to analyze the influence of different unloading construction methods on the structural reliability during construction to improve the quality of construction safety. In this paper, ANSYS version 16.0 software is used to establish a finite-element analysis model of the truss structure of the Harbin railway station. The synchronous unloading process and asynchronous unloading process are numerically simulated, and the stress variation trend of the arch truss during the unloading stage is studied. The research results show that the effect of simultaneous unloading on the mechanical state of the structure is small. During the unloading process, stress is more likely to exceed its limit in the area where the boundary conditions change. Then axial strain monitoring was performed during the actual unloading process of the truss structure of the Harbin railway station. The results show that the effect of synchronous unloading on the structure’s stress state is small, which is in good agreement with the numerical simulation results.

Adjacent buildings of three to five stories with small spaces between them are widely used as offices, schools, and hospital wards. The seismic resilience of such buildings is critical, and retrofitting adjacent buildings by integrating them into a common isolation system is considered effective. The resilience-based retrofitting of adjacent RC frame–shear wall buildings was investigated through a case study. First, the critical engineering demand parameters (EDPs) dominating the resilience performance of such buildings were identified. An isolation scheme was designed to improve their seismic resilience, emphasizing control effect of seismic isolation on critical EDPs. The effect of the yield ratio of the isolation system on the seismic resilience of retrofitted buildings was investigated by comparing three cases. A yield ratio of 2.5% is preliminarily recommended as a valuable reference for the resilience-based retrofitting of adjacent RC frame–shear wall buildings.

Internal defects in rail may affect the safety of the train travel and deteriorate the infrastructure of rail transit. However, the existing manual defect detection mode has difficulty coping with the increasing mileage and defect detection data. To accomplish the comprehensive detection of internal defects in rail, we propose a waveform subtraction recognition method based on rail defect features in B-scan images. First, rail structure waveforms are detected based on the You Only Look Once (YOLO) v4 network. Then, after removing normal structure waveforms, abnormal waveforms of defect are located. Last, according to the law of B-scan imaging and relationships with structure waveforms, abnormal waveforms are screened and classified into specific types of defect by the rule base. The detection method was tested on a real-world data set, and the test results showed that the accuracy of normal waveform detection was 0.871 and the accuracy of defect detection was 0.755. Furthermore, previous defect detection methods were compared, and results showed that the proposed method is feasible for the comprehensive detection of rail defects.

Performance assessment is important for existing infrastructures because it can effectively help conduct maintenance and keep the structure in good condition. In this study, with the database of sign structures provided by the Maryland State Highway Administration (MDSHA), a probabilistic-based analysis approach, with reliability concept, is developed for the assessment of sign structures for the state of Maryland. This approach uses structural members’ combined stress ratio (CSR) and fatigue stress ranges based on a standard specification as failure criteria. In existing sign structures, the focus is on Type CN2 (planar cantilever sign support), which is the category with the largest proportion of fatigue galloping-sensitive cantilever structures, and Type OH6 (box truss overhead sign support), which is the category with the largest proportion of overhead structures. Eventually, the failure probabilities of CN2 and OH6 groups are obtained, indicating which portion of sign structure is at high risk. Results of this study on sign structures will provide a basis for future inspection and maintenance of the infrastructure system.

Large deformation of the surrounding rock may also occur in hard rock tunnels under certain circumstances. Taking the construction of the jointed and altered granite stratum in the Zangga Tunnel, China, as a case study, the paper analyzes the surrounding rock deformation characteristics and influencing factors in the jointed and altered granite stratum, and explores the control measures for the large deformation by the numerical analysis and the field application test. The results show that the accumulated deformation value and the deformation rate have large values, and the horizontal convergence is larger than the crown settlement. Geological reasons, such as an active fault and alteration, are the internal factors of large deformation, whereas the high in situ stress situation and other reasons are the external factors. The numerical analysis results show that the optimized support structure has the capability to control the deformation. Numerical analysis results show that the optimized structure can control the deformation and the plastic zone range. The field test results show that the deformation rate and value are well-controlled after adopting the control measures, and the field construction efficiency is significantly enhanced, indicating that the control measures presented have a good construction effect in this stratum.

Sandwich wall systems provide resistance over a large deformation range, making them useful for blast resistance. This paper analyzed three sandwich panel systems: walls with symmetric concrete layers (SW), unsymmetric concrete layers (NSW), and symmetric concrete layers with prestressed reinforcement (PSW). Nonlinear three-dimensional (3D), finite-element (FE) modeling, and single degree of freedom (SDOF) analysis were performed to analyze the static and dynamic response of these wall systems. The numerical models showed good correlation with the experimental results. A parametric study was performed to investigate the effect of several parameters such as concrete compressive strength, symmetric and asymmetric steel reinforcement, tie-connector type, and pretension force value. It was found that asymmetric reinforcement has approximately the same action as symmetric reinforcement, and increasing the compressive strength did not increase significantly the blast resistance of the panel. Moreover, glass fiber–reinforced polymer (GFRP) pins provided the maximum composite action and blast resistance of the different tie-connector types investigated.

Prioritization of maintenance and rehabilitation interventions according to their urgency, expected improvements, costs, and downtimes is a necessary task in facility management. This is particularly of interest in critical facilities requiring nondisrupted operations or minimal stoppages such as hospital buildings. Maintenance scheduling is currently performed in hospitals in a purely subjective manner where experts categorize the importance and priority levels of different interventions and plan them according to their associated cost. Despite its popularity and workability, this process can be criticized for its high dependence on the expert’s knowledge and experience as well as its sole dependence on cost as the main driver for applying interventions. Therefore, in this paper, an objective methodology is developed to select the most suitable interventions and accordingly group the different actions together. This is expected to minimize the overall downtime and disruption caused by the maintenance and rehabilitation works in healthcare facilities. Introducing a combined artificial intelligence-based methodology, a triobjective optimization model is primarily utilized to select the interventions expected to maximize the overall performance of the facility as well as inhibit the minimum levels of costs and downtime. The output is further fed into an unsupervised machine learning model where interventions are grouped together according to their relevancy on a hybrid clustering approach, integrating between hierarchical and $K$-means clustering algorithms. This yields an action plan for use by maintenance personnel to schedule the disruptions of critical spaces (i.e., intensive care units and operation rooms) within the hospital building. This helps ensure a smooth and continuous operation in the facility as well as prevent any harm to facility occupants that could result from maintenance and rehabilitation works.

In order to analyze the influence of the position relationship between the fault and the tunnel on the water inrush, the fault is regarded as a constant head boundary, the bounded aquifer is transformed into an unbounded problem by the reflection method, and a simplified calculation model of the tunnel water inrush is constructed. Based on the theory of groundwater mechanics, Darcy’s law, and the linear superposition principle, the calculation expressions of water inflow and structural external water pressure are derived, and degradation analysis is performed. The correctness of the model is verified by numerical simulation and field test data. Afterward, the sensitivity of the characteristic parameters is studied, and the influence mechanism of the grouting structure and faults on the tunnel water gushing is discussed. The research results show that in order to ensure the safety of the secondary support structure of the tunnel, appropriate grouting circle thickness and a permeability coefficient should be set, and the permeability coefficient of the secondary support structure should be appropriately increased. When the seepage is stable, the tunnel water inflow will increase nonlinearly with the increase of the fault dip, and the sensitivity will gradually increase; when the fault dip is fixed, with the increase of the distance from the tunnel, the restriction of the fault on the tunnel is weakened, and the water inflow decreases continuously. In the case project, the theoretical and measured water inflows of the unfaulted section, single-faulted section, and combined-faulted section differ by 13.36%, 12.79%, and 10.85%, respectively. The difference between the theoretical value and the measured value of the outer edge water head height of the secondary support structure was 10.7%, 10.51%, and 13.87%, respectively. The research results can provide a theoretical basis for the calculation and structural design of tunnels in water-rich fault areas.

The extreme multihazardous event involving a truck collision and an air blast is a low-probability, high-consequence event for bridge piers. This study aimed to numerically investigate the performance and failure modes of multicolumn piers under a medium-sized truck collision combined with an air blast. Full-scale, finite-element models of multicolumn piers with three configurations were developed using LS-DYNA software with a soil domain restraining the foundations. The accuracy of modeling approaches was verified by comparing tested and simulated results. The collisions were simulated using a single-unit truck (SUT) at velocities ranging from $65\mathrm{km}/\mathrm{h}$ to $120\mathrm{km}/\mathrm{h}$ and combined with air blasts at different scaled distances. Analyses were completed to examine damage propagation and dynamic response during the extreme multihazards. The results showed that after the SUT collision compromised pier capacity, further deterioration occurred from the subsequent air blast, resulting in severe damage and even failure of the pier. In addition, parametric studies were conducted to assess the effects of several load and design parameters on pier performance and identify the controlling parameters. Representative failure modes of multicolumn piers under truck collisions combined with air blasts were assessed. The findings from this study provided a comprehensive understanding of multicolumn pier response to the extreme multihazards and developed recommendations for the practical design and analysis of the multicolumn pier.

This study presents a new mathematical equation for calculating the pile group efficiency in cohesionless soil under combined axial and lateral loading conditions, considering the tapering angle effect. Based on the mathematical definition of the pile group efficiency, analytical correlations are developed. The tapering effect is considered by developing a new geometry coefficient for efficiency associated with the shaft vertical bearing component of tapered piles. In addition, a simplified mathematical equation is developed for predicting the group interaction factor as a function of pile spacing, number of piles in the group, diameter of the cylindrical reference pile, tapering angle, and pile slenderness ratio. On the other hand, an array of three-dimensional numerical analyses is performed for modeling same-volume single bored piles and pile groups with various arrangements to capture the accuracy of the proposed mathematical equation. The hardening soil constitutive model is adopted for the modeling of piles in loose sand. Subsequently, the load-displacement diagrams of single piles, as well as pile groups, are obtained. The bearing capacities of straight-sided and tapered bored piles are then calculated and compared using a definite settlement criterion. By computing the various bearing-capacity components, group efficiencies can be attained from both numerical and mathematical analyses. The results indicate an acceptable agreement between both analyses. Finally, the developed equation can predict the pile group efficiency incorporating the tapering angle and other influencing parameters as a novel and simple relationship under simultaneous axial and lateral loading conditions.

Hinge joint damage is the main defect affecting the safety of assembled hollow slab bridges. The timely discovery of hinge joint damage is significant for guaranteeing the structural safety of assembled hollow slab bridges. This paper presents a damage detection approach for hinge joints of hollow slab bridges using mode shapes extracted from moving vehicle responses. A stationary excitation vehicle equipped with a shaker excites a bridge, another vehicle moves along the driving path, and its acceleration is collected to extract the mode shape, which is called the stationary excitation extraction mode (SEEM) method. First, the theoretical analysis model of the proposed method is established to analyze the response of the vehicle–bridge system, and the mode shape is extracted from vehicle acceleration by the Hilbert transform. An algorithm that requires no baseline is adopted to detect damage from the extracted mode shape. Then a procedure for damage detection in field testing is proposed in which the determination of important parameters is explained, including excitation frequency, moving vehicle departure time, and narrowband filtering. Finally, factors that affect the accuracy of the approach are studied by numerical analysis, including road roughness, vehicle speed, damage degree, and damage location. The results demonstrate that the damage detection approach for hinge joints is feasible at low vehicle speeds.

Liquefied natural gas (LNG) is cleaner and cheaper for power generation than traditional energy sources. Many tanks that store LNG are located in coastal areas with less favorable geotechnical conditions and often in seismically active regions. The seismic loads acting on LNG tanks are highly affected by the soil–foundation–structure interaction (SFSI) and evaluating this effect is quite challenging as a result of the nonlinear response of the structure and foundation interacting with the soil. This paper presents the application of a three-dimensional (3D) numerical simulation technique to study the impacts of foundation type on the seismic behavior of a large LNG tank considering the SFSI effects. Fully nonlinear dynamic analysis under the influence of the 1994 Northridge and 1995 Kobe earthquakes are performed using finite-element analysis software ABAQUS version 2018 to assess the LNG tank seismic response under different foundation types, namely, end-bearing pile foundation and pile-raft foundation with two different frictional pile lengths. The results show the importance of the SFSI effect in evaluation of the seismic response of LNG tanks built on pile foundations. Indeed, choice of the deep foundation system and composition of the foundation in terms of raft effects and pile length can significantly change the dynamic response of an LNG tank and thus seismic forces in the foundation and superstructure.

This study investigated the performance of microbially induced calcite precipitation (MICP) in reinforcing road bases reconstituted with calcareous or silica sands. Four testing models were prepared by the surface percolation method at two cementation levels. A series of tests for California bearing ratio (CBR) and unconfined compressive strength (UCS) were performed to examine the strength of biotreated samples at the model and element scales. Scanning electron microscopy (SEM) tests were conducted on specimens sectioned from the four road base samples to investigate the microstructure of the biotreated sands. The test results showed that the strength of the biotreated road bases increased and then decreased with an increase in soil depth due to clogging in the upper layer. Calcareous sand samples demonstrated better biotreated performance than silica sand samples. The SEM results showed that the calcium carbonate (${\mathrm{CaCO}}_3$) produced by MICP treatment can coat and bond grains and fill voids, which is more apparent in the upper portion of the bases. The morphologies of the ${\mathrm{CaCO}}_3$ precipitate in the calcareous and silica sand samples were different; this probably resulted from differences in the grain roughness and minerology of the two sands.

This paper presents and discusses the experimental and numerical results performed on a 3D modular steel frame under sudden corner support removal scenarios. A modular steel frame was designed according to Australian standards and fabricated in full scale. An experimental testing program was developed in which the module was examined under some robustness scenarios as sudden loss of one or two corner supports. The 3D dynamic response of the module was captured during the robustness (loss) scenarios, and the possible damages are reported. In addition, the detailed numerical finite element micromodel of the module was created, employing continuum solid elements. The numerical model was verified against the experimental results; based on that, other numerical models were generated to study the effects of mass distribution and different boundary conditions in real modular assemblies under corner support loss scenarios.

The applicability of the capacity-based design approach to buildings consisting of cross-laminated timber (CLT) shear walls has lacked analytical expressions that depend on the structural type and failure mechanisms. This project developed such expressions for multipanel CLT shear walls used in multistory buildings with emphasis on including the bidirectional contribution of the angle brackets. The proposed method addresses the hierarchy of yielding among different groups of dissipative zones. New categories with dissipative and limited energy dissipative capabilities were introduced, and expressions for overstrength factors were defined. The proposed procedure was verified using numerical models, and insignificant differences were obtained between the proposed method and the numerical models. It can be concluded that when the proposed conditions are met, the desired coupled-panel behavior can be achieved and the angle brackets can be assured to remain elastic. It was shown that when the applied shear force is calculated based on the proposed methodology, it correctly coincides with the yielding of the hold-down obtained from the numerical models. Additionally, a case study was presented for a two-story building composed of multipanel CLT shear walls to demonstrate the suitability of procedure beyond a single story.

Distresses in concrete and timber bridge components occur due to physical, chemical and mechanical factors that manifest as observable symptoms of deterioration. Deterioration models relate the observable defects to the several factors affecting the deterioration. Only limited studies exist on the development of non-parametric (NP) models for bridge management, which have the unique advantage of not requiring any assumption on the functional form of the models. To address this research gap, this paper develops non-parametric deterioration models for risk and reliability assessments of concrete and timber bridges based on two methods: (1) average time in condition rating (ATICR), and (2) Kaplan-Meier (K-M) estimates. This study proposes relative deterioration rates based on the ATICR of various concrete and timber bridge components. The methodology for developing NP deterioration models based on K-M estimates for probabilistic prediction of bridge safety while accounting for the partial information from the incomplete bridge condition observations is explained. This study also investigates the effect of multiple factors affecting the bridge component condition, including aging, traffic loads, environmental conditions, and design characteristics, and estimates the median survival years for reinforced concrete decks.

In the present work, dynamic analyses are performed on a footbridge considering deterministic and probabilistic models with two distinct formulations of a human walking loading simulation, a force model (FM) and a biodynamic model (BM). The probabilistic analyses are based on the random walk (RW) method in order to realistically represent the pedestrian movement with interperson and intraperson variability approaches. For the methodology’s development, a theoretical-experimental correlation is performed based on tests of one and six people crossing a steel footbridge. A performance assessment is carried out following current guidelines along with a statistical analysis using RW. The study aims to provide a better understanding of the structure in serviceability scenarios using the two probabilistic RW loading models with FM and BM (RWFM and RWBM). The results show that most of the maximum acceleration amplitudes reaches the unacceptable comfort limit using the RWFM, and the comfort level is improved in the simulations using the RWBM. The results obtained in the proposed simulations point out that the use of RW successfully simulates the slight variations present in the walking cycle.

Due to the constraints of structural bearing, guardrail elevation, and milling depth of cement-paved bridge deck, the white-to-black maintenance of concrete bridge deck always has been a technical problem in road maintenance. This paper proposes a technical solution to the maintenance of concrete bridge deck by using a hot-mixed ultrathin wearing course. The road performance and construction technology were studied. The results of indoor performance tests show that the residual stability of Marshall immersion tests and the ratio of freeze–thaw splitting strength were greater than 90, and the rutting dynamic stability was $\mathrm{4,786}\mathrm{times}/\mathrm{mm}$, with better water stability and high-temperature performance. The results of engineering application show that the effect of application of hot mixed ultrathin wearing course in the white-to-black maintenance project of the concrete bridge deck is meaningful, and the test results of the performance indexes such as the skid resistance, flatness, and water seepage of the pavement are excellent. However, it is necessary to create drainage channels on the bridge deck.

The improvement of facility maintenance and operation practices for constructed buildings is a major concern for all facility management (FM) firms worldwide. The owner, planner, and developer of housing projects, especially projects that are repeated, are eager to enhance the quality of the coming projects based on satisfaction of the current facility occupants. Little research has been conducted to link occupants’ requirements and satisfaction with FM practices or with the design of future facilities. The main purpose of this research was to determine students’ satisfaction with and obtain their qualitative feedback regarding a hostel facility to determine whether the constructed facility is providing the performance needed by users of the facility. The research also evaluated the housing facility from the occupants’ perspective and correlated this with the current maintenance practices to improve the maintenance planning and the overall performance of the facility. A survey covering 56 different performance attributes was conducted using a questionnaire distributed to the students. The overall level of satisfaction with the studied attributes indicated that the students generally were satisfied with the housing facility. This study will enable the maintenance administration and the university management to identify areas of students’ dissatisfaction with housing facility, which will help to improve the performance and the overall satisfaction. Thus, the results and findings from this study will keep the quality of future constructed students housing up to the desired standards and level of service. The study contributes to the body of knowledge on improving student accommodation in higher education and provides valuable insight to the facility management.

The statistical characteristics of structural defects of shield and cast-in-situ subway tunnels are of great significance for risk assessment, preventive maintenance, and reduction of safety accidents. In this study, the apparent defect indexes, statistical characteristics, probability models, and index correlations of different lining types of subway tunnels are studied. First, quantitative and objective statistical indicators suitable for modern subway tunnel detection technology are proposed. Then, the statistical characteristics of defect data from the two different tunnel lining types are analyzed. Using the maximum likelihood estimation method, a probability analysis of the defect indexes is carried out, and the quantile test method is used to verify the probability analysis results. Finally, the correlation between defect indexes is discussed through correlation and regression analysis. The results indicate that the influence of different lining types on the defect characteristics of subway tunnels is different, and the corresponding statistical characteristics are significantly different. The probability distribution models of the two tunnel types are obviously different due to different quantitative bases of defect index severity, and appropriate probability distribution models for some indexes cannot determined. There is a certain correlation between the defect indexes of shield tunnels, but this correlation is weak in cast-in-situ tunnels. The safety evaluation index of tunnel structures can be selected according to the index correlation, and type and weight of the index of different lining types should be treated differently.