Journal of Performance of Constructed Facilities

The aim of this study is to clarify the parameter-determination issue with regard to the viscous damping and contraction joint friction in the underwater explosion (UNDEX) resistant design of arch dams. A 141-m-high double-curvature arch dam is chosen as the study subject, and the finite-element program ABAQUS/Explicit is employed. Both the dam-reservoir interaction and the contraction-joint nonlinearity are considered. The calculation results suggest that in a routine range of values for the viscous damping ratio (less than 0.05), the damping effect on the UNDEX-induced displacement and damage responses of the arch dam seem limited. To be conservative in the design, the viscous damping ratio could be assigned a zero value (neglecting the damping effect). The calculation results have highlighted the importance of the monolith-to-monolith friction to the tensile damage to the dam base. We believe that a value of 0.65 assigned to the friction coefficient should be appropriate for the UNDEX resistant design of an arch dam in case the shear keys’ shear-transferring roles are not considered.

Indirect fastening is not yet a well-vetted method for attaching stone cladding from the point of view of designers and contractors, and a high incidence of failures has been observed in the field, suggesting inadequate design or inappropriate installation specifications. In fact, it has been shown that inadequate design is often responsible for significant defects that subsequently arise over the course of the facade life cycle. This study is intended to help determine the influence of cladding design parameters on the service life of natural stone cladding with an indirect fastening system. For that purpose, a survey of the state of degradation of 142 buildings in the Lisbon area was performed, based on visual inspections that allow describing the extent of the cladding area affected by the different anomalies evident on the cladding. A weighted numerical index of the extent of the cladding’s degradation ($E_w$) is established, thereby allowing identifying both the positive and negative impacts of each design characteristic on the service life of an indirectly fastened natural stone cladding system. This study analyzes the influence of parameters such as the type, size, color, density, and type of finishing of the stone plates; the location of the cladding in the facade; and the characteristics of the fastening system. The results obtained reveal that claddings with larger stone plates, with natural stones of lower density, located in taller areas of the buildings and with dowels located at less than $1/5$ of the plate’s length from the corners present a higher incidence of defects, with higher deterioration rates. The information obtained in this study can be used by designers in order to mitigate the negative impact of some design characteristics, adopting adequate solutions that increase the durability and service life of indirectly fastened natural stone claddings.

Adjacent box beams are widely used for constructing short- and medium-span bridges on roadways throughout the United States. The performance of a straight, noncomposite-adjacent box beam bridge under a live load is well understood, while the behavior of a composite-adjacent box beam bridge constructed using beams poured into a form with a skew angle, known as a skewed adjacent box beam bridge, is not. The focus of this research is the evaluation of the in situ performance of the skewed composite-adjacent box beam bridge located on Dry Creek Road in Granville, Licking County, Ohio, which is a single-span bridge with a 28° skew angle. To evaluate the overall bridge behavior under live loads, the beams were instrumented with strain gauges and linear variable differential transformers (LVDTs). The live load testing was performed using a tandem axle dump truck and single-axle truck under both static and quasi-static controlled load conditions. The experimental results from the current work were used to evaluate three characteristics representative of bridge response: lateral load distribution, skew effect, and shear key relative displacement. This work proposes that the composite-adjacent box beam superstructure components behave as an integral unit resisting the applied load. Additionally, the skewed geometry distributes the strain asymmetrically across the width of the bridge. Most of the applied loads correspond to a diagonal path to the supports at the obtuse corners. The measurement of the relative displacement showed that most of the shear keys experience cracks. Ten months after the truck load test, the reflected cracks were visible on the bridge deck. The cracks occurred where the highest relative displacements were measured. The measured longitudinal tensile strain showed that the load is transferred effectively from one beam to another. The current work also suggests that the cracks developed in the shear keys do not have a significant effect on the load distribution between adjacent box beams because the presence of the composite deck enhances load distribution.

Large power transformers are both expensive and vulnerable to seismic failure. Excessive amplification of earthquake loading to power-transformer bushings beyond the bushings’ rated strength can occur if the system’s structural dynamics produce unpredictable and unfavorable resonance behavior. Determining the degree of vulnerability to large seismic amplifications is not straightforward, and general design recommendations do not always resolve problems that can potentially arise. This paper considers a number of case studies in an attempt to postulate a set of critical factors that might facilitate better prediction of bushing amplification. Furthermore, several additional case studies are summarized in order to add to the evaluated data set and provide more validity for drawing broader conclusions.

Earthquakes have always attracted civil and geotechnical engineers’ attention, especially when it comes to the liquefaction potential of soil. This paper investigates the feasibility of classifier based on stochastic gradient boosting (SGB) to explore the liquefaction potential from actual cone penetration test (CPT) and standard penetration test (SPT) field data. SGB is composed of many classification and regression trees which meet the mechanism of ensemble learning and show strong predictive power compared with conventional statistical learning models in several engineering applications. The binary classifier was built by the database gathered from CPT and SPT filed data for predicting the non-liquefaction or liquefaction of soil, the SGB hyperparameters are optimized by grid search method with tenfolds cross validation methods. Three performance metric, namely Cohen’s Kappa coefficient, classification accuracy rate and receiver operating characteristic curve, are used to evaluate the predictive performance of SGB approaches. With CPT and SPT test sets, highest classification accuracy rate of 88.62% and 95.45%, respectively, are achieved with SGB. It is confirmed that the SGB can be applied to characterize the complex relationship between the liquefaction potential and different soil and seismic parameters with great efficiency. Further, relative importance of influencing variables for each model are investigated and demonstrated that the SGB predictor is more sensitive to the indicators of initial soil friction angle for SPT data whereas cone tip resistance for CPT data.

Pedestrian-induced actions cause high vibration amplitudes in flexible and lightweight structures such as cable-stayed bridges. The high vibrational response is considered a serious serviceability problem that must be avoided either at the design stage or when retrofitting the structure. The use of control devices, particularly tuned mass dampers (TMDs) and viscous dampers (VDs), can be justified to reduce the structural dynamic response. This paper concerns the optimum design of a cable-stayed steel footbridge and its control devices to withstand a running event while guaranteeing all the serviceability criteria. Four different techniques (no control, VD, and VD with passive or semiactive TMDs) are presented to illustrate the effect of these control strategies in the optimum design geometry, dynamic responses, and cost.

Accelerated corrosion techniques are used to assess the structural performance of corroded reinforced concrete elements. This paper aims to illustrate the use of various techniques by showing their advantages and disadvantages. Two different corrosion techniques were investigated: constant voltage and constant current. Each technique was used to corrode a full-scale structural element. Two reinforced concrete two-way slabs were prepared and cast for this purpose. The slabs had identical dimensions of $\mathrm{1,900}\times \mathrm{1,900}\times 150\mathrm{mm}$. Each slab had a column stub with a cross-sectional area of $250\times 250\mathrm{mm}$ and a height of 200 mm. The two slabs were corroded to the same level of 25% mass loss. The setup and procedure for each technique is described in detail showing its appropriateness and difficulties. The corrosion of each corroded slab was evaluated on the basis of the experimental results of current measurement, half-cell potential readings, crack patterns, natural frequency, chloride content, and mass loss. The theoretical mass loss was calculated on the basis of Faraday’s equation for both techniques. After the induced corrosion process was completed, the concrete cover was carefully removed and the corroded bars were extracted, cleaned up, and weighed. It was found that the actual mass loss for the corroded bars showed a close agreement with the theoretical mass loss for both techniques. The corrosion causes cracks on the concrete surface, which facilitate the flow of electricity between the anode and the cathode. In the case of the constant current technique, the cracks do not affect the current intensity because the current is kept constant under controlled conditions, whereas in the case of the constant voltage technique, the cracks cause fluctuation in the current value. Thus, the current intensity could reach extreme values, which affect the damage that occurs in the corroded element. Hence, constant voltage may cause more damage than would occur under uniform corrosion conditions when a constant current is used.

This paper presents the results obtained from an island-wide investigation program for anchored slopes alongside freeways, highways, and railways in Taiwan. The investigation procedures include the visual inspection of anchor protection caps and anchorage head components, borescope inspection of strands under anchorage heads, and lift-off test to determine residual anchor loads. It was found that groundwater and corrosion were the common problems associated with ground anchors. Immediate measures were taken to backfill cavities under anchorage heads to prevent further corrosion on existing anchors. The upper and lower bounds of the remaining capacity of existing anchors was assessed using a t-distribution statistical method; also, if necessary, extra anchors with better corrosion protection were installed to restore the degraded stability of slope due to anchor corrosion. A low-cost smart anchor capable of self-detecting load changes is also proposed. Use of such smart anchors will allow the anchor load changes on a slope to be monitored on a large scale over an extended period of time and provide needed anchor information for assessing the future stability of anchored slopes.

In the current changing climate historic timber frame buildings are exposed to ever more severe and frequent extreme weather conditions such as floods and wind driven rainstorms. These structures are especially vulnerable to moisture ingress and subsequent decay. In light of this there is a need to better understand and quantify the impact of this exposure on the mechanical behavior and capacity of such systems. Here an experimental investigation is presented which sets out a novel test method for measuring the impact of cyclic wind driven rain and flood exposure on the lateral stiffness and strength of masonry infilled timber frames. Empirical data presented here indicates losses in elastic stiffness exceeding 75% as a result of exposure, whilst analytical assessment confirms the failure mechanism that describes yielding of the system in weathered and unweathered states. This work has measured the extent of structural decay in direct relation to the meteorological parameters wind speed and precipitation accumulation, giving deeper, understanding of the vulnerability of the structural system of masonry infilled timber framing to these climate phenomena.

The present study aims at the probabilistic seismic risk assessment of a base-isolated building frame under near- and far-field earthquakes by conducting a fragility analysis. For this purpose, a base-isolated 10-story reinforced concrete frame was considered having lead rubber bearing as the base isolation system. Fragility curves were developed for an ensemble of far-field and near-field (including directivity and fling-step effect) earthquakes, and for a number of damage measures, namely, maximum interstory drift ratio (MIDR), maximum base shear (MBS), maximum roof drift ratio (MRDR), maximum top floor acceleration (MTFA), and maximum isolator displacement (MID). Moreover, to investigate the effect of frequency contents of near-field earthquakes, the peak ground velocity (PGV) to peak ground acceleration (PGA) ratio of near-field directivity earthquakes was considered as a variable. Two sets of near-field directivity earthquakes were considered, one having a low $\mathrm{PGV}:\mathrm{PGA}$ ratio, i.e., less than 150 ($\mathrm{cm}/\mathrm{s}/g$), and the other having a high $\mathrm{PGV}:\mathrm{PGA}$ ratio, which is greater than 150 ($\mathrm{cm}/\mathrm{s}/g$). The incremental dynamic analysis was conducted to create the fragility curves by assuming different threshold values of damage states, namely, slight, moderate, extensive, and collapse. The results of the study indicate that even for the low PGA level, the near-field earthquakes cause a high probability of exceedance for the base-isolated frame. The $\mathrm{PGV}:\mathrm{PGA}$ ratio has a significant effect on the damage probability for the near-field earthquakes because the high $\mathrm{PGV}:\mathrm{PGA}$ ratio had greater damage probability compared to that of low $\mathrm{PGV}:\mathrm{PGA}$ ratio.

Limited studies have investigated the progressive collapse of three-dimensional (3D) semirigid steel–concrete frames due to the complexity of modeling techniques, intensive computational time involved in the analysis, and lack of experimental work. A simplified numerical model was developed using nonlinear dynamic analysis procedures. Single column removal cases were considered in different story levels and at various locations. Results of three different types of connections—double web angle (DWA), top and seat angle with double web angle (TSD), and double-tee angle (T-stub) were compared with those having a rigid joint to highlight the effect of connection rigidity. The analysis results showed that the vulnerability of progressive collapse in the corner column removal scenario on the ground floor for DWA connections is higher than that of other removal situations. Three-dimensional skeleton frames and two-dimensional (2D) frames cannot capture the realistic behavior of the structure under progressive collapse. In consecutive column removal cases, the vulnerability of progressive collapse drastically increases. Finally, the paper presented new retrofitting schemes to improve collapse resistance, which will be useful for researchers and structural designers.

The need for the restoration of buildings that have been suddenly damaged either by natural or human factors affects the tenants of the buildings and can generate posttraumatic stress. Few studies have been conducted on how to repair buildings under such circumstances, and no tools are available that facilitate either the decision-making or the management of social factors under a strategy that simultaneously considers social, technical, and planning aspects. In these cases, an intervention can be considered successful when it is technically and socially satisfactory for the tenants throughout the whole process of rehabilitation work. The emergency work that took place in a building of 40 dwellings is analyzed, which, following damage to an adjacent building, involved the evacuation of all residents and the immediate implementation of psychological first aid and building damage containment. The work was completed successfully in all aspects: economic, temporal, and social. The technical solutions and their implementation are discussed. Finally, an innovative model of action for the restoration of buildings under emergency conditions is proposed.

Upgrading the flexural design strength of the structural member for increased live load without disrupting the functionality of the structure is an arduous task. One such problem was investigated in this study by using low-modulus ($<125\mathrm{GPa}$) carbon fiber–reinforced polymer (CFRP) for retrofitting of structural steel members. Although most researchers use normal (up to 250 GPa) or high-modulus (above 250–640 GPa) CFRP for flexural strengthening of steel structures, the use of low-modulus CFRP for such applications has been largely unexplored. The present study demonstrated the feasibility of low-modulus CFRP by experimental testing using different retrofitting techniques such as flange wrap, flange-web wrap, and closed wrap. A total of 18 steel beams were tested under four-point bending that includes two control specimens and 16 CFRP-strengthened specimens. In each strengthening scheme, enhanced CFRP wrapping configurations were introduced based on the failure modes observed from the previous wrapping configurations, thereby the strength, as well as the failure mode, improved. In general, the experimental results indicate that the design strength of the structural steel member subjected to flexural loading can be increased up to $\sim 50\%$ by using the low-modulus CFRP strengthening schemes.

Unexpected banging noises occurring on the Beomseo Bridge in Ulsan, South Korea have been reported during and after the steel box-girder erection. The banging noise, which at maximum reached 120 dB, raised concerns among drivers and nearby residents about the safety of the bridge. This paper aims to experimentally investigate the source locations and causes of these randomly occurring noises and propose methods for noise control. A vibroacoustic monitoring program was conducted using measuring devices such as sound level meters, acoustic cameras, and accelerometers. The data were analyzed to determine noise source localizations, causes of banging noises, and mechanism of noise generation. Based on the finding that changes in the temperature of the girders led to increases in the number of noise occurrences, bridge investigation results showed that stick-slip motion in the spherical bearing resulted in these abnormal noise events. To reduce the banging noises, two possible methodologies for noise control were proposed: (1) noise source modification, and (2) control of the transmission path.

Face stability is critical for the safety of underwater tunnel construction across fault zones. This paper presents a new analytical method that can be used to assess such stability. Following Horn’s model and the double strength reduction method, a new analytical model is proposed which incorporates the effects of groundwater seepage, fault dip angle and excavation footage. By evaluating separately the frictional resistances of the rock and the fault mud of the sliding body, two reduction ratios ($k_1$ for the fault mud and $k_2$ for the rock) are determined. The influences of the fault dip angle, hydraulic pressure, and excavation footage on the tunnel face stability were demonstrated in a case study using the proposed new model. The case study showed that the frictional resistance due to fault mud contributes little to the stability of tunnel face as $k$ increases. With the increase of the fault dip angle, the stability of the tunnel face improves; however, from another perspective, the frictional resistance distributed in the fault mud contributes little to the safety of the whole sliding body as $k$ increases, and the stability of the tunnel face is improved as the dip angle increases, whereas the influence of the fault mud on the whole stability weakens. A smaller fault dip angle causes a more severe warp, indicating that the dip angle significantly affects the shape of the subtraction factor curves. On the other hand, the hydraulic pressure plays a more significant role in determining the shape of the curves compared with the fault dip angle. It was observed that both subtraction factors $f_1$ and $f_2$ were much greater under higher hydraulic pressure. In addition, the overall safety factor $f_s$ decreases with the increase of the distance between the tunnel face and the fault plane ($l$). All curves with different fault dip angles tend to converge to the same safety factor as the value of $l$ approaches zero, whereas different fault dip angles lead to different rates of variation of $f_s$ against $l$. Further numerical results showed that the maximum vertical displacement ($Y_{\max }$) of the tunnel face increases with the reduction of $l$, and the axial displacement of the tunnel face center ($Y_{\mathrm{center}}$) for different fault dip angles is the same when $l$ approaches zero.

This study investigated earth pressure balance (EPB) shield tunneling–induced responses in terms of muck pressure, machine parameters, and surface settlements using an efficient numerical scheme that couples PFC3D and FLAC3D software. Tunneling cases with different discharge ratios in the chamber were conducted using PFC3D, and the surrounding ground was modeled in FLAC3D. The results showed that the muck pressures near the bulkhead vary periodically during shield tunneling and have negative relations with the discharge ratios. Pressure differences between the left and the right sides in the shield chamber, and at different longitudinal positions, were found to be subject to the discharge ratio in the chamber. Furthermore, negative relations between the discharge ratio and both the thrust in the shield and the torque in the cutterhead were observed during excavation. Finally, it was found that positive ground loss has a larger effect on surface settlement than its negative counterpart.

Buildings are complex systems, and therefore truly understanding their performance is difficult. The cost of maintenance is a real problem and a major issue in building projects, and it constitutes a significant part of the total facilities management (FM) cost. This study intends to examine the factors attributed to increased FM cost and the building components’ difficulty level of operating and maintaining. A literature analysis identified 16 factors responsible for increasing FM costs and 28 building components that are hard to operate and maintain at the postoccupancy stage. That analysis was followed by a questionnaire survey, and 31 respondents graded the identified factors using a five-point Likert scale during an online survey. The mean and relative importance index (RII) of the factors and building components were determined, followed by rank analysis. This study demonstrates that design errors, lack of maintenance plan, lack of understanding of FM, underestimating the impacts of FM, and lower maintenance quality significantly affect the FM cost performance. Among building components, roofs, construction joints, façades, HVAC, and sewer lines were rated as the most difficult to operate and maintain. Finally, the relationships between the factors influencing FM cost and the building components were identified using correlation tests. This study provides insight into the major factors of FM cost performance and difficulty level of building components for maintenance.

Leakage dissolution and the induced internal erosion failures in earth-fill dams and foundations significantly threaten the long-term operational safety of geotechnical structures. This phenomenon can be more dangerous in conjunction with the damage of internal water-supply bottom outlets due to the leakage-induced pore water pressure, which reduces soil effective stresses and therefore affects dam stability. However, the internal instability induced by bottom outlet leakage has not been thoroughly investigated. Therefore, in this paper, a bottom outlet leakage model testing system is designed to simulate and investigate bottom outlet leakage in earth-fill dams. This leads to a detailed investigation on seepage behavior in earth-fill dams, by considering the different positions of bottom outlet leakage, i.e., at the upstream side, the middle dam section, and the downstream side. Furthermore, numerical analyses are carried out to study the leakage-induced slope instability. Based on the experimental and numerical results, the following phenomena are observed: (1) when bottom outlet leakage occurs, the whole phreatic line is elevated and hydraulic head increases significantly at the leaking position. The equipotential line bends to the point of leakage and the seepage field at the leakage point is drastically affected; (2) in the direction perpendicular to the bottom outlet, the hydraulic head decreases nonlinearly as the distance from the bottom outlet increases; (3) seepage discharge increases as hydraulic head increases, in an approximately nonlinear relation. The seepage discharge due to bottom outlet leakage at the upstream side of the dam is much larger than that at the middle dam section and the downstream side; (4) the factor of safety of slope stability decreases as leakage-induced hydraulic head increases. The potential failure surface of the dam slope is circular when leakage occurs at the middle dam section and the downstream side. For the failure at the upstream side, seepage-induced tensile stress reaches the tensile strength, which leads to slope damage; and (5) based on the experimental and numerical investigations, suggestions are given for designing the monitoring scheme for bottom outlet leakage problems in earth-fill dams.

To ensure the safety of constructing the north anchorage excavation of Fuma Yangtze River Bridge, an extensive instrumentation program was carried out to monitor the performance of the excavation. This monitoring effort included the ground movements of soil outside the excavation zone, ground movements of the tops of piles, lateral deflections of piles, and prestress in cables. Based on an analysis of the monitoring data, the following findings were obtained: shallow landslides were induced by rainfall at several locations outside the excavation zone, and the movement directions of soil were consistent with the natural terrain. The horizontal displacements of the west and east top beams were generally larger than that of the north side. The vertical movements of the tops of the piles exhibited heave initially and then transitioned into settlement. The deflected profiles of the piles were similar, and the maximum lateral pile deflections were very close. The measured deformations and internal forces of the support system did not exceed the alarm values, which suggested that the excavation was in a stable state.