Journal of Performance of Constructed Facilities

This paper presents an overview of the design, construction, and performance of the modular strong-block testing system. The purpose of this project was to create an economical alternative to large-scale structural engineering laboratories for smaller programs with more versatility than traditional self-contained frames capable of conducting full-scale experimental tests. The system discussed herein consists of 12 individual reinforced concrete strong blocks that, when post-tensioned together, creates a self-contained testing system. The system was evaluated by testing two reinforced concrete beams subjected to a vertical load and two reinforced concrete shear walls subjected to a horizontal load and monitoring the forces in the Threadbars used to post-tension the system, uplift of the system, and the slip between blocks. The system was more flexible than expected, but the overall behavior of the system was satisfactory. The results show that the system remained composite under load and confirm the feasibility of the design.

The seismic behavior of unreinforced masonry (URM) structures has usually been investigated by conducting laboratory tests. Such efforts, although useful in order to understand the response of single walls or subassemblages, cannot fully mimic the in situ seismic response of masonry buildings. In this study, in situ lateral load testing of a two-story full-scale URM building was conducted. First, forced vibration tests were performed to determine the vibration frequencies of the building. Afterwards, the building was tested by reacting against a braced steel frame built behind the test building and imposing one-way cyclic displacements. The building was pushed until 20% loss of lateral load capacity, which corresponds to a drift ratio of approximately 0.8%. The diagonal tension cracking of the walls was followed by sliding of the second-story concrete slab over the walls. A three-dimensional nonlinear finite-element analysis of the test building was conducted to simulate the behavior of the test building. The results showed that upon careful selection of the contact cohesion at the slab–wall interfaces, the numerical model provided reasonable estimations of the global structural behavior in terms of load-deformation response.

This paper presents the results of a field study carried out on three reinforced concrete (RC) structures built in the 1960s, 1970s, and 1980s to determine the main load (environmental) and the resistance (for example, the concrete quality and clear cover) factors affecting the durability of the infrastructure in the harsh environmental conditions of the Arabian Gulf region. The effects of degradation, such as the carbonation depths and chloride concentration profiles, in the columns, beams and slabs were determined from concrete core samples. To determine the durability factors, the concrete resistivity to electrical charge, the rapid chloride permeability, and the sorpitivity were measured. Digital image processing was performed to estimate the cement contents and the proportions of other ingredients used in the concrete samples. In most of the structural members, the chloride threshold for steel depassivation had been surpassed and the carbonation had reached the steel surface. The spalling of the concrete cover was observed with severe corrosion damage to the reinforcing bars. It is expected that this study will help understand the degradation phenomena in RC structures in the Gulf region and similar hot, humid, and saline environments. The results will help to establish the input parameters for the chloride diffusion and carbonation models in aggressive environmental conditions. Because the concrete quality directly impacts the initiation of many deterioration processes such as corrosion of the steel reinforcement and carbonation, the results could be used to predict the remaining service life of existing RC structures with similar concrete properties.

Suspenders are critical force transmission components in suspension and arch bridges, which connect the girder to the main cable/arch. Field inspection indicates that short suspenders at the midspan or the ends of a bridge may be more prone to fatigue damage under cyclic traffic loads when coupled with the effects of corrosion. The damage has been frequently observed to occur at the lower ends of suspenders. To evaluate the safety of suspenders, a stochastic time-variant reliability assessment method is proposed, where the time-variant model for deterioration of steel wires and probabilistic critical limit states based on crack depth and failure area are integrated, so as to consider the combined effect of corrosion and cyclic loading. A case study on the suspenders of the Jiangyin Yangtze River Bridge was performed in which a finite-element analysis was conducted in conjunction with a comprehensive traffic model. The time-variant reliability indices of the short suspenders were obtained according to the proposed method, which resulted in recommendations for suspender maintenance and replacement.

Road bioretention is one of the promising low impact development (LID) best management practices (BMPs) for the construction of sponge cities. Design of the media used in the soil layer of a bioretention facility is critical to its performance regarding infiltration, filtration, and storage of a high volume of runoff from impervious areas. In this study, a coarse aggregate void filling (CAVF) method was adopted for the design of bioretention soil media. The key hydrological parameter of the bioretention media, the average matrix suction at its wetting front, was estimated through finite-element simulation of the rainfall infiltration process. Using the obtained parameter, a bioretention structure was designed, then modeled in the Storm Water Management Model (SWMM) software to analyze its potential hydrologic benefits in terms of reduction in both peak flow and total volume of surface runoff into storm drains in a rainfall event. It was found that the permeability of bioretention soil media is the key factor that affects outflow reduction ratio, peak flow reduction rate, and peak time of the system. The bioretention media composition design method adopted in this study seems promising for use in the material and structural design of road bioretention facilities for sponge cities.

With a significant number of steel bridges approaching the end of their service life, understanding deterioration characteristics will help bridge stakeholders better prioritize bridge maintenance, repairs, and rehabilitation as well as help with budget planning. This paper applies data mining techniques including logistic regression, decision trees, neural networks, gradient boosting, and support vector machine to the United States’ national bridge inventory to estimate the probability of steel bridge superstructures reaching deficiency. A focused subset of data was created based on the defined scope of the research: design material (steel), type of design (stringer/multibeam or girder), and deck type (cast-in-place concrete). The predictors of the model include age, average daily traffic, design load, maximum span length, owner, location, and structure length. The magnitude that these factors contribute to the likelihood of a steel bridge superstructure’s deficiency was identified. Outcomes of the analysis afford bridge stakeholders the opportunity to better understand the factors that are correlated to steel bridge deterioration as well as provide a means to assess risks of superstructure deficiency for the sake of prioritizing bridge maintenance, repair, and rehabilitation.

Constructed transport facilities in soft deposits deform significantly due to long-term land subsidence. A great deal of research has been carried out to study the land subsidence–induced deformations of metro tunnels, with a few focusing on the performance of highways in soft deposits. Based on extensive field data of the Shanghai Middle Ring Highway (SMRH), this paper investigates the long-term settlement behavior of the SMRH, which consists of ground road and elevated road. Annual longitudinal settlement profiles of the SMRH are presented to study the responses of the ground road and elevated road to land subsidence. The accumulated longitudinal settlements are compared to the ground surface settlements in association with geological conditions. Moreover, a comparison of the deformation processes between the elevated road and subsoils is presented. Field data indicate that the whole highway, including ground roads and elevated roads, settled in the earlier stage, but part of the elevated roads heaved since 2009. In the ground road part, ground road settled with the ground surface. However, in the elevated road part, the ground surface settled more significantly than the elevated road, with differential settlements ranging from 15 to 40 mm. The settlements of the elevated roads were invariably close to the total compression of soils below the pile tips and the elevated road heaved due to rebound of these soils.

Dynamic load testing has become a common practice for condition assessment of masonry arch bridges and laying the foundation for their rehabilitation procedures, yet additional dynamic testing after rehabilitation is rare. Carrying out dynamic load tests before and after rehabilitation programs produces valuable results regarding the structural changes of the bridge. This paper tries to assess the effects of ballast cleaning on controlling the increased vibrations transmitted to the bridge structure due to increasing the operational speed. To do so, a 70-year-old masonry arch bridge is instrumented with accelerometers and dynamic load tests are carried out before and after ballast cleaning and results are compared. According to test results, vibrations with frequencies of up to 200 Hz are reduced by almost 16%, while those with frequencies between 250 and 1,300 Hz are reduced by almost 41%. It is concluded that from a vibration point of view, cleaning the ballast could increase the allowable speed of the trains on the bridge by 18 km/h.

Wind-driven rain (WDR) refers to raindrops that have a horizontal velocity in the wind field. The WDR intensity on building envelopes as well as other issues such as wind–rain-induced vibration of stay cable has been extensively developed, whereas the mechanism and the effect of rain load acting on the structures are still not very clear. Based on the equations of motion of falling raindrops, the relationship between the raindrop horizontal velocity and corresponding wind speed is investigated under the effect of mean wind with or without turbulence. Further on, the simulation methods, referred to as the equation approach and program approach, are proposed to obtain the rain speed time history, based on which the formula for calculating rain load is established. Finally, the dynamic response analysis of a transmission tower subjected to wind and rain loads is carried out, and the results show that (1) when the rain intensity is up to $200\mathrm{mm}/\mathrm{h}$, the maximum displacement percentage induced by rain load relative to wind load has already reached 7%; and (2) when the rainfall intensity is assumed to be $709.2\mathrm{mm}/\mathrm{h}$, which is the heaviest rainfall ever recorded in China, the maximum displacement percentage at the tower tip is 15.4%, indicating that the effect of rain load on a transmission tower should not be ignored.

Postconstruction settlement that occurs before a tunnel is in operation may significantly influence the tunnel’s long-term stability. The current study investigates such a tunnel, a three-lane superlarge section tunnel in Gansu Province, China, to assess the long-term settlement performance of a loess tunnel using reinforcement from vertical jet grouting piles. A three-dimensional finite-element model, validated through field observations, is employed to simulate soil consolidation behavior. Results indicate that the long-term settlement, as determined by the finite-element method (FEM), corresponds with field investigation results. Specifically, most of the Fujiayao tunnel’s long-term settlement (nearly 90%) occurred within the first 60 days after tunneling. Settlement occurred at a relatively rapid consolidation rate and then gradually stabilized within 120 days with a maximum consolidation settlement magnitude of 14.99 mm according to FEM versus 12.89 mm from field observations. Compared to a case without reinforcement, consolidation settlement in the reinforced case was found to decrease significantly over a shorter consolidation period. Furthermore, the relatively large consolidation settlement surrounding the tunnel, as well as consolidation settlement overall, gradually and uniformly declined in an outward direction from the tunnel. The vertical jet grouting technique exhibited a strong reinforcement effect on the loess tunnel’s foundation and can be applied to similar soft foundation tunnel reinforcement projects to greatly improve the stability and safety of tunnels in operation.

Beam-column joints are regions of high inelastic stress concentration in reinforced concrete (RC) frames. Evidence of the vulnerability of the joints to damage during earthquakes is witnessed in panel zone failures. Corrosion of reinforcement will cause the deterioration of joint behavior under seismic actions, especially for structures in coastal areas. In the study described in this paper, the performance of corroded RC interior as well as exterior beam-column joints subjected to simulated seismic loads were investigated by employing a two-dimensional (2D) nonlinear finite-element (FE) OpenSees model of deterioration of materials as well as the bond-slip effects in joints. The accuracy of the model was verified and calibrated by comparing the FE analysis results against experimental results from the literature. After that, a parametric study was performed to investigate the impacts of some key parameters on the shear strength of corroded joints. A total of 360 specimens were simulated based on the FE model. Finally, these important parameters were integrated into two fitting equations to predict the shear strength of corroded interior and exterior beam-column joints.

The high strength of construction materials has allowed the design of elegant and architecturally appealing footbridges that are safe against static loads but may be susceptible to large vibrations when crossed by pedestrians. The low natural frequencies and damping of these systems can result in excessive or annoying movements. This paper presents two studies on the vibration serviceability of a footbridge. In the first part, details of the vibration testing and analysis of a slender two-span steel footbridge will be discussed. Vibration tests on the structure were conducted to verify the computer modeling and results of the dynamic analyses. The accuracy of the computer model was evaluated by comparing various dynamic properties and criteria. Lessons learned from the comparison of the results of the tests and analysis are presented. The second part of this paper presents a study of human-structure interaction (HSI) on the dynamic behavior of the footbridge. Results of vibration tests with a number of human subjects are compared with those from the computer modeling. They demonstrate the validity of the human models used, and the effect of humans on the dynamic properties and response of the structure.

The wind, storm surge, and flooding loads due to the 2017 Hurricane Harvey had a detrimental impact on the built infrastructure in coastal communities. This paper presents the lessons learned from damage to the built infrastructure in the Port Aransas region in Texas observed after Hurricane Harvey through reconnaissance and postsurvey data as well as statistical analyses and associated patterns of failure modes. The observations and findings of this study are also compared to empirical evidence from past hurricane-induced damage to buildings. A set of rapid and detailed damage assessment data is developed to focus on damage failure modes, distribution of damage to structural and nonstructural components, as well as repair, occupancy, and functionality status at the time of the inspection. The most common damage modes were identified as damage to roof components (roof shingles), vinyl siding, and interior nonstructural elements. It was also observed that the location of the building in the city and surrounding topography as well as structural age of the infrastructure were important parameters that influenced the response of buildings to hurricane-induced loads. The evidence from the performance of the inspected buildings shows the need for new design alternatives as well as sustainable retrofits for existing buildings such as incorporating heavier nailing schedules for roof sheathing and shingles as well as strengthening the connection of vinyl siding. In general, strengthening the envelope of the building to prevent surge and rainwater intrusion can significantly reduce damage.

Thermal actions have a great influence on the girder deflection variability of long-span cable-stayed bridges. The main objective of this study is to investigate the variability of the bridge girder deflection under thermal actions. A monitoring-based analysis of thermal actions and temperature-induced bridge girder deflection for a combined highway and railway cable-stayed bridge has been carried out; the correlation between the girder deflections at different positions is analyzed; a detailed analysis on the correlation between the structural temperature and the girder deflections has also been performed. Furthermore, the double thresholds with a specific probability for the deflection estimates are proposed. It is revealed that a strong linear relationship exists between the structural temperature and girder deflections. The proposed method can provide good estimates of the bridge girder deflections based on long-term monitoring temperature data.

Disputes and repairs due to window condensation problems frequently occur after the completion of apartments. However, most repairs are performed individually and confidentially by construction participants, who are forced to minimize economic losses. Thus, actual cases of inspection and repair for condensation defects have rarely been addressed in public even though condensation on windows remains the primary cause of defect disputes. This study aims to contribute to the resolution of similar disputes by presenting an actual case of a new apartment complex in which defect disputes arose from window condensation; the condensation resistance performance was inspected, and repair measures were proposed. On-site measurements and mock-up tests were performed. The results demonstrated that the $U$-factor satisfied its required specifications but that the temperature difference ratio did not satisfy the requirements. Repair measures were proposed and evaluated; the combination of adding sealant, double glazing near the existing glazing, and an insulation cover on the frame was found to be effective. These repair measures were applied to the apartment complex and the number of condensation complaints decreased significantly.

A facile and effective method for retrofitting simple shear tab connections in a steel gravity frame is presented to improve its overall lateral force-resisting capacity. At a target shear tab connection, the existing gap between the beam flange and column face is snugly filled with a tapered steel plate, which is then field-attached to the column face. When a steel gravity frame is subjected to lateral loads (due to, for example, earthquake and strong wind), the retrofitted shear tab connection deforms and promptly engages the beam to bind the column via the filler plate, thereby exerting a horizontal thrust to the column at the retrofitted beam flange level. Hence, the moment arm between horizontal reactions increases and so does the flexural capacity of the connection. Numerical results from detailed finite-element analysis confirm the role of beam binding action enabled by the present method in satisfactorily enhancing both the strength and stiffness of shear tab connections as a gravity frame deforms laterally.

The technical performance assessment of a building is essential for planning maintenance actions to improve its condition and functionality. The aim of this study is to present a building inspection system for evaluating the technical performance of existing buildings, considering the importance of the entire building and the interdependence of its parts. A questionnaire survey to identify the main defects that affect the technical performance of a building was administered. The system was then validated on a university campus that houses 22 buildings. The results revealed three main applications of the proposed system: a comprehensive asset analysis, a building operation analysis, and a risk analysis system.

In this paper, in order to develop a novel probabilistic model for the time-dependent compressive strength of concrete for existing reinforced concrete buildings, 1923 data sets were obtained by applying a rebound hammer in 33 buildings. In addition, 172 data sets were obtained using core drilling in 27 (out of 33) buildings with service-ages varying from 1 to 60 years and located in Shanghai, China. By analyzing the experimental data, it is found that the normal distribution appropriately describes the distribution of normalized concrete compressive strength. The conjugate prior distribution was used to update the mean value of the normalized compressive strength of concrete by rebound hammer. Then the time-dependent mean value of the normalized compressive strength by rebound hammer and core drilling was proposed. The results of the numerical models agree well with the measured data. The compressive strength conversion factors of the concrete tested by rebound hammer and core drilling methods are provided as well. The proposed probabilistic model for the time-dependent compressive strength of concrete and the conversion factors can be used to efficiently predict the compressive strength of concrete for existing reinforced concrete buildings.

This paper presents findings from a research project on the development of a numerical framework to predict the collapse load of a wharf supported by corroded piles under gravitational loads. Data from a detailed marine investigation performed in 2012 were used to analyze the structure. The nonlinear responses of corroded piles were predicted using detailed finite-element analyses and incorporated into a simplified model of half of the wharf. This paper investigates the performance of the structure and its dependence on the superstructure stiffness, substructure redundancy, and distribution of the degree of pile corrosion. The findings indicate that increasing the stiffness of the superstructure up to a limiting value results in enhanced load redistribution capability of the structure, a larger number of buckled piles prior to collapse, and a higher collapse load. The results also show that buckled piles may continue to support loads close to but less than their peak capacities if the superstructure is stiff and strong enough. The paper provides a framework for assessing the performance of similar highly redundant, heavily deteriorated structures.

The case of the abutment of a motorway urban viaduct damaged by human intervention is presented. Built in the 1960s, it lies in a critical seismic area and the human-induced damage involved the elements of the abutment foundation. The structure is geometrically complex and the evaluations of its structural safety were carried out by applying Italian codes from different times: those concerning the time of construction, those of a recent past (1996), and those of the present (2008), inspired by Eurocodes. A comparison between the safety checks performed and the requirements of all these codes is presented and discussed, especially regarding safety coefficients after the damage was done. Two different structural models were performed: a simplified one focused on the foundation plate and piles for a first approach of the analytical evaluations; and a complete three-dimensional finite-element model of the bridge on which numerical simulations were carried out for different load combinations and in which all structural elements were considered (deck, abutment, and foundation). The main aspects, believed to be the fundamental ones for specific evaluation of the global and local structural safety, are discussed. A hypothesis for restoration is presented, as well as the relevant technical and administrative items linked to the application and reliability of the Italian code on existing structures.

Understanding the compressive behavior of reconstituted clays plays the central role for many infrastructures, particularly for those built in coastal areas. This paper presents an enhanced approach for the determination of intrinsic compressibility of reconstituted clays with different initial water contents. Following the conventional practice of geotechnical engineering, the compression curve is expressed by two straight lines in the bilogarithmic space, with a remolded yield stress being introduced to distinguish two linear segments. On the basis of extensive experimental data from literature, parameters for the description of two linear segments can be obtained through a pair of functions of initial void ratio and void ratio at liquid limit. Then, an enhanced equation for intrinsic compressibility is formulated to replace empirical approaches based on curve fitting. The proposed equation contains a small number of parameters, which can be obtained through consolidometer tests. This approach is validated through comparison between model predictions and experimental results of remolded clays under a wide range of effective stresses and initial water contents. Application of this approach is demonstrated through interpreting a pilot test for the improvement of dredged marine clay slurry in a castle tideland area of China. A case study once again proves the capability of the proposed approach and also highlight its applicability.