Journal of Performance of Constructed Facilities

The widely-utilized multispan simply-supported adjacent (side-by-side) box girder bridges often suffer from problems of deterioration attributable to transverse cracking in link slabs between spans, malfunctioning expansion joints, and longitudinal cracks between adjacent girders. Such problems can degrade the functionality, durability or even safety of the bridge over time, depending on the environmental exposure conditions. This paper discusses an approach taken to rehabilitate the Shili Bridge by eliminating expansion joints and retrofitting the structure from simply-supported box girders into a continuous bridge. Condition assessments were performed before retrofitting. In addition, several design options and construction procedures were considered and analyzed. Static and dynamic load tests were carried out after the completion of rehabilitation. The lessons learned in this project are presented and discussed. This practical and novel methodology is a step forward toward improving safety, sustainability, reliability, and quality of such existing bridges in China and elsewhere.

The deteriorating state of the built environment has affected numerous sectors, and hospitals are no exception. Hospitals are relatively unique compared with other facilities because of the complexity of their systems and their criticality with respect to the communities they serve. Faced with limited budgets and pressures to comply with increasing performance requirements, hospital facility managers are required to strike a delicate balance between hospital maintenance costs and level of service requirements. Accordingly, this paper proposes a reliability-centered maintenance (RCM) approach that is combined with evolutionary optimization to develop optimal maintenance plans for hospital facilities. The scope of the developed model covers four mission-critical systems in hospitals, namely medical gases, primary HVAC, secondary HVAC, and elevators. Failure-mode effect analysis (FMEA) is used to determine the optimal maintenance strategy for various components within these systems. The model considers how each system contributes to the continuity of services in four areas within hospitals, namely intensive-care units, emergency rooms, operating rooms, and regular patient rooms. In order to demonstrate the capabilities of the developed model, a case study of a $\mathrm{5,200}\text{-}{\mathrm{m}}^2$ hospital is considered. Results demonstrate that by using the RCM and optimization approach, savings ranging from 6 to 16% in maintenance costs can be realized in comparison with traditional preventative maintenance approaches undertaken by existing maintenance contracts. The developed model is thus capable of providing hospital facility managers with an effective tool to better understand how their maintenance expenditures directly contribute to overall system availability and impact healthcare services delivered to patents.

The lighting system is an important infrastructure that needs to be maintained to curb degradations caused by aging and other extraneous factors. Facility managers are responsible for system operations and confront challenges resulting from the considerable number of maintenance requests under various limitations (e.g., budget, labor resources). Therefore, maintenance activities need to be evaluated continually to improve their efficiency. As for the lighting system, the choice of maintenance methods [i.e., spot relamping (SR) and group relamping (GR)] has typically been made based on rules of thumb and experience. In this respect, this contribution aims to develop a framework that allows facility managers to use systematic analysis to select the most appropriate relamping strategy. The proposed framework integrates analytic hierarchy process (AHP) and simulation methods based on a preset clustered network. The framework is composed of three phases: relamping cost evaluation, carbon dioxide (${\mathrm{CO}}_2$) emission evaluation, and comprehensive evaluation for decision making on maintenance alternatives. A case study of lighting maintenance is provided to demonstrate the applicability of the framework to the selection of an optimal relamping alternative in consideration of cost and environmental protection. Finally, a sensitivity analysis is conducted to better understand the effect of variations in the clustered network and the importance of environmental protection in the choice of the lighting maintenance procedure.

Progressive collapse has drawn significant attention from researchers because of its potential to inflict severe damage and casualty. Much research has focused on simulation techniques for collapse, but comparatively little has examined the interactions among the three main mechanisms of flexural, compressive arching, and catenary actions by way of simplified methodologies. This paper introduces a theoretical method to calculate the collapse resistance of reinforced concrete frame structures in static progressive collapse analysis. The lumped-damaged plasticity method was used to simulate flexural analysis, and compressive arch and catenary actions were calculated using geometry analogies assuming rigid body rotation after initiation of plastic hinging. The method was validated by comparing the simulation results with experimental data, wherein reinforced concrete beam-column assemblies subjected to column removal were tested pseudostatically. The flexural and arching actions were well predicted by the proposed methodology, though the assumed failure mechanism at the end of the simulated catenary action was conservative compared to the experimental results. Overall, the developed method integrating flexural, compressive arch, and catenary actions during collapse was found to be a reliable tool for quick estimation of collapse resistance in static progressive collapse resistance.

The body of knowledge on design for maintainability (DfM) is increasing. However, there is currently no systematic analysis of the diversified DfM-related issues and research. Through a systematic review of selected papers from the well-known academic journals in the construction and facility management fields, this study identified the major research areas of DfM from the management and technical perspectives. The major research areas identified include (1) maintainability implementation status and significant barriers, (2) critical management factors that affect achieving DfM, (3) maintainability scoring systems, and (4) innovations and technical advancement to achieve DfM. This study not only analyzed the state of the art and trends in DfM research but also discussed the gaps in research and proposed future research directions. The findings of this study may also serve as a platform for both researchers and practitioners to retrieve the latest developments and trends in DfM.

Although they are classified as nonstructural elements, infill walls in reinforced concrete buildings are considered critical because they affect structural behavior and performance. Therefore, the identification of the mechanical properties of infill walls is important. This study performs code-based experiments to identify the mechanical characteristics of infill walls in a reinforced concrete building and evaluates the results on the basis of the dynamic behavior of the building. The compressive strength, modulus of elasticity, and initial shear strength of the infill walls, made of horizontally tiled bricks and cement mortar, are determined by testing wall specimens extracted from an existing building and are incorporated into the numerical analysis to determine dynamic properties of the building. The obtained dynamic properties are compared to those derived from the operational modal analysis. A modification is required in the modulus of elasticity of infill walls to confirm the building’s dynamic behavior. The identified modulus of elasticity of the infill walls proves the reliability of the vibration survey as a tool to evaluate mechanical properties of infill walls in reinforced concrete buildings.

Safety assessments of river bridges have attracted a great deal of attention from researchers. Regardless of whether a bridge is being constructed or retrofitted, an integrated analysis of many factors, such as hydraulic conditions, geological conditions, and structural strength, is necessary. A three-dimensional finite-element model is used here to perform structural analysis. The uncertainty in important parameters (such as water level, water flow rate, scouring depth, and the N value of the standard penetration test) was considered via a reliability analysis. A parameterized bridge model was established to perform the iterative calculations required for the optimization and reliability analysis, in which the preprocessing, solution, and postprocessing were all performed automatically to facilitate a reliability-based optimization. To reduce the number of calculations, a surrogate model was adopted, in which the reliability analysis uses the first-order second-moment method and the optimization uses the particle swarm optimization method. A numerical example (the Dongshi Bridge) is given to demonstrate the methodologies proposed in the study.

The paper describes the failure scenario of a precast building that collapsed during the 2012 Emilia earthquake. By means of time-history analyses on a detailed finite-element model, the dynamic behavior of the structure was investigated and the most reliable causes producing the seismic collapse were established. All collapse mechanisms (column failures induced by exceeding the shear force capacity, attainment of ultimate chord rotation, equilibrium instability of columns due to second-order effects and loss of support due to sliding at the double-tee slab-beam and beam-column friction-based supports) were monitored for the whole earthquake duration. The collapse scenario obtained from the interpretation of numerical results was compared with that suggested by the in situ inspection, confirming that friction-based supports (with absence of connection mechanical devices), typically adopted in Italy in precast technology when no seismic design provisions were prescribed, are inadequate to carry medium-high horizontal seismic loading. The modeling criteria and the procedure adopted for safety checks until the attainment of a collapse condition are presented and discussed.

Scour-induced reduction in bridge stability can develop vulnerabilities during a probable seismic event. This problem has been typically addressed by researchers as if these two extreme events have no joint probability of occurrence for a given range of time. This paper evaluates the stability of bridge piers subjected to various flood events followed by different seismic events with some known probability of occurrence. An analysis guideline is set for a probabilistic method to develop a matrix of analysis. In the case study, changes in structural response and stability of a bridge pier are identified using this probabilistic approach. Six different flood conditions evaluated under four different seismic events are analyzed to assess the structural stability. The low-level and high-probability flood events in combination with a moderate seismic event are determined to negatively affect the structural response. The reduction in structural stability is checked for column flexure, pile axial load, pile moment, and pile shear capacities.

This paper presents behavior of both unreinforced masonry and reinforced masonry (RM) building models subjected to dynamic loading with the help of shake table testing facility. The first masonry model was a half-scale conventional unreinforced masonry model. The second model was strengthened with welded wire mesh (WWM) and coarse sand mortar. Both the models were subjected to several ground motions. It was observed that the strengthened model performed much better than the unstrengthened model and there was no damage in the strengthened model. In this paper, the observation of the test results and the influence of strengthening in terms of damage intensity and failure pattern have been presented.

In earthquake engineering, the performance-based design method is used to determine the expected performance level of structures under an earthquake effect. The level of performance is related to the damage situation that could occur in the structure after the earthquake. In performance-based structural design, it is predicted that more than one damage level can emerge under one earthquake effect. In this study, the seismic behavior of a reinforced-concrete shear-wall building that collapsed during the 2003 Bingöl earthquake was investigated by nonlinear static analysis and nonlinear dynamic analysis. The selected reinforced-concrete shear-wall structure is located in Bingöl, Turkey. Local code was considered for assessing a seismic performance evaluation of the selected reinforced-concrete shear-wall building. The performance goals of the reinforced-concrete shear-wall structure were evaluated by applying the pushover (incremental equivalent earthquake load) method and procedures of the code and nonlinear dynamic analysis. According to the code, the reinforced-concrete shear-wall building was not expected to satisfy life safety performance levels under a design earthquake. In this study, one collapsed building was selected in order to test the reliability and usability of performance analysis methods under different earthquakes.

Deep excavation projects in urban areas may adversely affect underlying tunnels. Differential settlement and additional stresses in existing tunnels occur frequently due to excavation construction, which leads to the opening of circumferential joints or even to water leakage. To ensure the security of existing tunnels under deep excavation during construction, this paper proposes a risk assessment methodology that aims to evaluate the risks of circumferential cracks of preexisting shield tunnels. Existing tunnels are assumed to be a beam on a Winkler elastic foundation. The longitudinal deformations of the tunnel and internal forces in tunnel structures are obtained from the singular function method. Based on the equivalent axial stiffness theory, the relationship between the opening of circumferential joints and the additional bending moment is established. The Monte Carlo simulation technique is used to quantitatively estimate the potential risk levels of circumferential joints. The calculated results are verified by in situ observations.

Cracking in concrete deck has been the major concern to bridge designers as well as owners. Excessive cracking not only would affect the performance and serviceability of the bridge but also reduce the service life of the concrete deck and increase the maintenance cost. It is proven that many factors could cause the cracking of concrete deck including restrained shrinkage, temperature effects, applied live load, and improper construction sequence. Among these factors, appropriate construction staging plays an important role in minimizing the cracking of concrete deck, especially for multiple span continuous bridges. However, the construction staging has not been subjected to detailed research in the past. Therefore, it is important to evaluate the current concrete deck construction staging practice and propose an optimized construction staging for multiple span continuous bridges, if needed. In this study, the research approach adopted is aimed at investigating the cracking of a typical multiple-span continuous bridge, evaluating the construction staging, and providing an optimized practice for deck construction staging. A typical three-span continuous bridge was selected for investigation and various types of sensors were instrumented on the bridge to monitor the behavior of the structure during and after construction. The finite-element (FE) model was developed and validated with the data collected from field testing. Based on FE analysis and experimental data, the cracking of the bridge deck was investigated and alternative construction staging scenarios were simulated and compared. Moreover, based on analysis results, an optimized deck construction staging practice was recommended for future use.

In order to adapt to a new site planning of the Porcelain Tower of Nanjing, China, two two-story and one three-story historical masonry building built in the 1930s were translocated. Because of the limited ground space, the three buildings were divided into eight parts and reconnected after translocation. The moving routes had multiple broken lines to avoid influencing surrounding old trees, and the maximum translocation distance was 184 m. Some building units were rotated by 7 degrees or lowered by 4.2 m, in accordance with the new site planning. Procedure and technical details of the translocation, including the structural strengthening, load underpinning, structural separation, ground treatment and reconnection, etc., are introduced in this paper. One building was pulled by a traditional hydraulic-jack system with high-strength steel strands; the other two buildings were moved by using a novel translocation device, which is capable of self-walking and turning 360 degrees, in order to change the translocation direction more efficiently. Through the vertical hydraulic jack in this new translocation device, the undesirable difference in column settlements can be automatically compensated, which loosens the requirement on the rail stiffness.

Finite-element (FE) model updating is a very effective procedure for determining the uncertainty parameters in a structural model and minimize differences between experimentally and analytically identified dynamic characteristics. This procedure can be practiced with manual and global/local automatic model updating procedures. Automatic model updating is very popular because of its applicability to all kinds of engineering structures to minimize differences, and its damage localization and structural health monitoring. This paper considers a historical masonry bastion to obtain its dynamic characteristics numerically with the finite-element method and experimentally with ambient vibration tests (AVTs). Sensitivity analyses for the uncertainty parameters and manual and automated model updating to minimize differences are also performed. A castle bastion located in Trabzon, Turkey is selected as an application. The FE model of structure is developed in commercial software. The first three natural frequencies are obtained between 5 and 10 Hz, and AVTs are performed under natural excitation using enhanced frequency domain decomposition (EFDD) and subspace structural identification (SSI) techniques. The first three natural frequencies are obtained between 4 and 7 Hz. The comparison of analytically and experimentally identified dynamic characteristics shows a close agreement between mode shapes, but 26% difference in natural frequencies. To minimize the difference, the FE model of the bastion is updated using manual and global/local automated updating, changing its material properties of Young’s modulus and material density. The maximum differences are reduced from 27 to 3% with manual updating, and to 0.02% with automated model updating.

This paper estimates the wind-resistance of a lightning-damaged transmission tower. The buckling cause of a tower member under lightning excitation is reexamined through an overall tower model, and the modelling method of the lightning-damaged transmission tower is presented. The static wind-resistance of a transmission tower is estimated with the consideration of initial eccentricity and nonlinear behaviors of material and geometry, and two influencing parameters are discussed. According to the simulation results, the basic wind speed of collapse decreases dramatically due to lightning damage, and the collapse modes of the original and lightning-damaged towers are very different. As a consequence, more attention should be paid to lightning damage of transmission towers.

The present study investigated the vulnerability of damaged building frames to sway collapse under seismic excitation. Crucial to the investigation was the identification of the critical damage scenario that triggers complete or partial sway collapse. This was accomplished by a simulation procedure aided by genetic algorithm, plastic analysis, and pushover analysis of the frame. The procedure, genetic plastic pushover analysis (GPPA), enabled creation of various potential damage scenarios that lead to the collapse of the frame under response spectrum compatible earthquakes of different intensities, represented by the peak ground acceleration (PGA) values. The damage scenario, which required the least value of the PGA for collapse, was identified as the critical damage scenario. If a frame had a damage scenario the same as the critical damage scenario, then it was likely to collapse under a similar earthquake having a PGA equal to the least value of PGA as described previously. A 10-story steel building frame was used as an illustrative example to demonstrate the application of the method. The result of the study was validated by performing a nonlinear time history analysis for response spectrum compatible ground motion, and by comparing analytical prediction with existing test results available in the literature. The numerical results showed that there exist certain localized damages in a building frame that may trigger collapse, leading to complete failure under an earthquake. If the damage of the building can be evaluated beforehand, the building’s vulnerability to collapse under future earthquakes can be predicted using the methodology presented in this paper.

This research examines the reasons for water treatment plants failure based on the analysis utilizing fault tree analysis. Qualitative analysis was used to achieve 33 basic events that lead to 12 minimal sets of fault tree analysis data representing the minimum plant failure probability. There is a great probability that 1 of the 12 minimal sets from the fault tree analysis will causes problems and failures in the fundamental operation of the facility. The research suggests a new method combining diverse experts with a range of theories to assess the probability of events in order to avoid the problem of lack of precision that will be faced when assessing the basic events. The proposed method was applied on the Sixth of October Water Treatment Plant as a case study. The data are used to determine the likelihood of a fault tree. Probabilities of the top event (TE) and the basic events (BEs) are calculated using Boolean relationships. The occurrence probability of TE is 15.6% per year. After ranking all risks, the researchers find that the most critical risk based on the probabilities of basic events is the failure of the electrical system, which has a high probability (0.037) with a high impact in the occurrence of failure. The proposed method describes the importance of using the measures in the sensitivity analysis of water treatment plants.

With the continuous construction of high-speed railway networks in China, long-span railway bridges which carry multiple tracks are being put into service on the high-speed railway line. However, few studies focus on bridge dynamic behavior and train running performance of high-speed railway bridges traversed by multiple trains. Base on a four-track railway bridge, the Nanjing Dashengguan Bridge, the dynamic analysis of the bridge considering the intersection and the parallel of multiple trains is performed using the train-track-bridge dynamic model. Then the acceleration responses of bridge girder and train running parameters are evaluated in the loading cases of multiple trains at different train speeds. The results show, first, that the transverse acceleration responses of the girder depends on the running direction of trains (intersecting or parallel). The maximum transverse acceleration of the two-train parallel case is obviously smaller than that of the single-train case, whereas the maximum transverse acceleration of the two-train intersecting case is greater than that of the single-train case. The maximum transverse acceleration of the three-train and four-train cases is close to the value of the single-train case and the two-train parallel case, respectively. Second, the vertical acceleration responses of the bridge girder depend on the number of running trains. The maximum vertical accelerations of the bridge are approximately in linear proportion to the number of trains running on the bridge. Third, the transverse train running parameters (especially the derailment coefficient and the transverse acceleration of the train car body) are the most detrimental in the two-train intersecting case, and are at a high level in the single-train case. Hence, the two parameters should be controlled in bridge design. The vertical train running parameter (especially the wheel unloading rate) is the most detrimental in the four-train case, and it becomes more significant with the increasing number of running trains. Hence, the wheel unloading rate should be controlled by the reasonable scheduling of running trains.

Using a mechanically stabilized earth (MSE) wall as a bridge abutment has become an attractive option to the traditional cast-in-place wall abutment. The use of an MSE wall abutment notably simplifies the design and construction of the bridge abutment, requires less site preparation, allows faster construction, and consequently leads to cost saving. The poor performance of an MSE wall may be related to construction conditions, the wall materials, and poor soil below the foundations. In this paper, the results of a large-scale inspection program are analyzed to identify the most frequent MSE wall problems, and a new inspection rating system procedure is proposed. This paper also presents a risk assessment method to determine the overall rating of the MSE wall after inspection and suggests a course of action. Finally, the paper presents recommendations for the design and construction methods to avoid future problems.

Failures of coastal low-lying bridges in the United States along the Gulf Coast have attracted substantial research interest. Many of the failures were associated with twin-deck bridges. This study presents a series of numerical experiments on the characteristics of the periodic wave loads on typical coastal low-lying twin-deck bridges. Firstly, a wave model using the Fourier approximation wave theory is used to represent nonlinear waves generated by a hurricane. The relaxation method is adopted for the numerical wave flume solving the Navier-Stokes (NS) equations in order to minimize the effects of wave reflection. The NS-based model is validated against laboratory measurements with good agreement. The characteristics of wave loads on a prototype coastal bridge with twin decks in the numerical wave flume are systematically studied by considering a variety of gap lengths between the twin decks. The deck gap lengths range from 1 to 40 m, covering the usual values for coastal twin bridges. Both the normalized horizontal and vertical loads on the twin decks under the prescribed conditions are analyzed in detail. Finally, a theoretical analysis of the effects of wave reflection by the landward deck on the characteristics of the wave loads for the twin bridge deck–wave interaction is presented. The results show that the wave loads on the seaward deck are larger than those on the landward deck and both the horizontal and vertical loads on the seaward deck vary as a function of the relative deck gap, the ratio of the deck gap to the wave length. The methodology of the twin bridge deck–wave interaction proposed in the current study can serve as a tool to determine the optimal gap length for a given design wave condition.