Journal of Performance of Constructed Facilities

Heritage in Mexico is endangered due to exposure to major hazard events and lack of maintenance. The level of knowledge necessary to evaluate structural behavior of historic buildings is generally low, mainly regarding the parameters such as mechanical properties. San Agustin church is one of the most important historical buildings in Morelia City, Mexico. Thus, a comprehensive analysis of the San Agustin church was performed, including a damage survey and dynamic identification tests. Based on the diagnosis, a 3D finite element model with solid elements was developed and calibrated. Then, a seismic assessment was carried out using pushover analysis. The findings about the damage obtained from the numerical analysis is consistent with the actual condition of the church. Finally, a partial model was developed to evaluate the performance of the nave barrel vault strengthened with an extrados masonry arch and a layer of carbon fabric-reinforced cementitious matrix, an intervention that substantially increased the horizontal load capacity.

Large-scale underground cavern projects are complicated in terms of construction technology, engineering quality, and safety. Moreover, the timely collection of vital construction information is difficult due to the complexity of the data and poor timeliness. In order to ensure the completion of construction progress and construction safety, this paper developed a real-time analysis and early-warning safety system for deep large underground caverns to automatically generate the early-warning level and corresponding emergency plans. There were two innovations involved in this system. On the one hand, a wireless monitoring and transmission platform is proposed to collect time-variable information from underground caverns. On the other hand, an early-warning safety framework is advanced, which contains abnormal recognition and early-warning information examination and verification, to support the whole-process management of integral safety for underground caverns. The system has been implemented successfully in an underground cavern construction project for Lianghekou Hydropower Station in China. The application demonstrates the proposed integration technology of real-time analysis and safety early warning can rapidly recognize abnormalities from massive monitoring data and provides a more accurate and reliable stepwise evaluation process for early warning.

The purpose of this study is to investigate the effect on flow hydrodynamics of grading of the bed and the mining of sand from the river bed around a bridge pier group. In total, 22 experiments with two different bed gradings (‘A’ and ‘B’), three different discharge rates, and Froude numbers were performed. In order to investigate the effect of mining on scour rate, the mining of material was carried out both upstream and downstream of the pier group. It was observed that the mining from downstream locations led to an increased scouring around the pier group. At a Froude number of 0.5, the existence of a pit hole downstream of the pier group causes a 3% and 9.7% increase in the maximum scour depth for grading ‘A’ and ‘B’, respectively. On the other hand, mining materials from upstream locations and for the same Froude number decreased scouring by 9% for ‘A’ grading and 8.1% for ‘B’ grading. A regression method was used to provide an equation that can be used to estimate the scour depth.

To date, cases of severe ground subsidence or abrupt cave-in failure of roadway without warning after crushing and removing boulders in the sand matrix by tunneling have been frequently reported in practice, which jeopardize the safety of pedestrians and vehicles and even cause casualties. Despite the severe consequence, it is still difficult for engineers to give reliable estimations on the ground subsidence hazards and then take suitable countermeasures or remedial measures in advance to prevent or mitigate relevant risks. In this study, failure mechanism of ground subsidence due to removing large isolated boulder in the sand matrix by tunneling and its adverse effects on tunnel performance were explored using numerical modeling. It is discovered that after removing the boulder, the soil stratum above the cavity maintained stability momentarily, and no clear sign of subsidence could be immediately observed at ground surface. With more and more sand particles falling off into the cavity over time, the soil particles nearby were mobilized which finally led to subsidence or cave-in of ground surface. Removing the boulder also incurred redistribution of bending moments and increase of axial stresses in the tunnel lining. In the end, the effects of tunnel cover depth and position of boulder along the tunnel circumference on ground subsidence and tunnel performance were also investigated. The findings in this study can serve as references for evaluating the risk of ground cave-in failure due to future tunneling work in similar geological conditions.

This study numerically evaluated the retrofitting of RC columns using different transverse rebar arrangements and retrofitting methods using European standard I-section profile (IPE) and fiber-reinforced polymer (FRP) coatings. The degree of deformation, failure pattern of the element, and residual axial strength of the RC columns after exposure to a blast were the performance criteria. Fifteen different models were evaluated to determine the effect of spacing and arrangement of rebars and the effect of FRP and IPE retrofitting. The results indicated that the RC element with transverse rebars with branches showed the least amount of deformation. Furthermore, the damage and deformation of the structure against blast loading decreased by 25% and 20%, respectively, when applying I-shaped profiles and RC columns with FRP coating. The residual capacity of the columns was highest in the models retrofitted with FRP and IPE.

This paper presents a five-step approach to estimate residual capacity of concrete members that undergo severe temperature-induced damage during fire exposure. Limited information pertaining to the fire event, including fire timeline, peak fire temperature, and compartment characteristics, is utilized to estimate fire severity in the first step. In the second step, peak temperatures experienced on exposed surfaces of the structural members at different locations in the structure (compartments) are estimated through visual inspection. A more detailed classification of temperature-induced damage in structural members based on information collected through visual assessment is performed in the third step. Subsequently, residual capacity of the structural member is estimated in the fourth and fifth steps through either simplified or advanced analysis methods based on the extent of damage as per the classification scheme. The proposed approach can be applied in practice for postfire residual capacity assessment of severely damaged concrete structures.

Due to the current deterioration of the environment, the performance degradation of reinforced concrete rainwater drainage pipes (RCRDPs) has become increasingly serious. Aiming at these problems and to provide the experience and ideas for scientific management of the pipelines, this study established an evaluation model for the performance of RCRDPs based on the combined weight-fuzzy theory. This study determined the evaluation index system and classification level boundaries, the subjective and objective weights of each index, the fuzzy evaluation matrix, and the performance level of the pipeline system. In addition, according to the radar chart analysis method, the performance of the cases was ranked and the specific repair plans were obtained. Finally, the scientific evaluation method was tested with the case study of 20 pipelines of DoaQung City. The research results show the following: (1) The combined weight of each indicator of the pipelines fully reflects the importance of them, overcoming the subjectivity of the analytic hierarchy process (AHP) and adopting the objectivity of the entropy theory. (2) The ranking of 20 pipelines comprehensive performance levels is $\mathrm{G}>\mathrm{F}>\mathrm{Q}>\mathrm{D}>\mathrm{H}>\mathrm{S}>\mathrm{B}>\mathrm{E}>\mathrm{N}>\mathrm{C}>\mathrm{K}>\mathrm{P}>\mathrm{L}>\mathrm{R}>\mathrm{A}>\mathrm{O}>\mathrm{J}>\mathrm{M}>\mathrm{I}>\mathrm{T}$, and this almost the same as the result of closed-circuit television inspections (CCTV). (3) The combined weight-fuzzy theory can be based on CCTV data to compare the status of each index, and the evaluated results are relatively scientific and reasonable. This research can provide a theoretical reference for the performance classification and maintenance of RCRDPs.

Long-span, single-layer spatial grid structures are widely used in public buildings. The progressive collapse of such structures could cause great losses of property and human life. To accurately capture the performance of a structure in progressive collapse, an efficient dynamic behavior analysis should be conducted. In this paper, a multi-degree-of-freedom simplified model was established to represent the progressive-collapse dynamic behavior of single-layer spatial grid structures. Based on the simplified model, two dynamic behavior modes were identified: ordinary and specific dynamic behaviors. In ordinary dynamic behavior, the dynamic effect caused by local failure cannot be transmitted, and the displacement responses of the joints in the failure area are symmetrically distributed based on the final equilibrium states, with the gradual attenuation of the dynamic effect. For the specific dynamic behavior, the dynamic effect is transmitted and a disorganized response of single-layer spatial grid structures occurs. Furthermore, the dynamic progressive-collapse behaviors of six full-scale typical domes were analyzed with a verified numerical simulation. The results indicate that a multi-degree-of-freedom system is necessary for accurately reflecting the dynamic behavior of single-layer spatial grid structures. The middle position between vertex and supports can be defined as the important area of reticulated domes, where a member’s failure would have a significant effect on structural performance. If a specific dynamic behavior plays a dominant role in the overall structure, the progressive-collapse resistance may be improved for a single-layer spatial grid structure.

Although an appropriate excavation sequence contributes to minimizing the excavation-induced impact on the underlying existing tunnel, few studies have focused on the comparison of the excavation sequence for engineering projects in practice. In this paper, the numerical simulations based on FLAC3D were carried out to discuss the excavation-induced impact on the underlying existing tunnel, and the numerical results were analyzed in combination with the field data through a case history. The influence of different excavation sequences on the underlying tunnel was interpreted in comparison with the practical construction process. The results show that the excavation directly above the existing tunnel is the main cause of the uplift deformation of the underlying tunnel and that the soil above both sides of the tunnel should be excavated preferentially. The timely application of the foundation pit floor structure, together with the uplift piles and isolated piles, forms a door-frame structure that can effectively suppress the uplift deformation of the underlying tunnel after the excavation directly above the tunnel.

Facility maintenance is critical to the proper function and utilization of facilities and fit and function are highly important to dormitories. This study analyzed 39,093 work orders from a US Air Force Computerized Maintenance Management System (CMMS) in order to holistically reveal the most common dormitory facility defects and their associated costs and the effect of preventative maintenance. Actual deficiencies and concrete costs can motivate owners, designers, and facility managers (FMs) to incorporate maintainability in early planning and design stages to reduce the overall life-cycle costs of the facility. The study found that most maintenance costs were associated with heating, ventilation and air conditioning (HVAC), water and gas systems, and architectural finishes and paint. The study also found that the total cost of the average work order was primarily influenced by labor costs. Critically, this study quantified the correlation between preventative maintenance (PM) and corrective maintenance (CM) and emergency work order labor hours, finding that PM was inversely related to CM and emergency labor hours. Finally, this paper suggests ways to improve maintainability decision-making in design, and operations and maintenance.

The sonic echo/impulse response (SE/IR) method is a versatile nondestructive method for evaluating the conditions of unknown bridge foundations. Previous studies have shown that the method has satisfactory performance in determining the length of concrete drilled shafts and wood piles. However, no significant success with steel H-piles has been reported due to the specific cross-section shape of such piles. Although previous studies have reported unsuccessful SE/IR tests, they have not discussed the effect of factors that can improve the methodology. In this study, the effect of hammer-tip type on obtained signals was investigated. SE/IR tests were conducted on two steel H-piles of a highway bridge with different striking hammer tips to examine if interpretable signals could be achieved. The results show that the hard tip with a contact time equal to $\mathrm{1,420}–\mathrm{1,880}\mathrm{\mu s}$ did not produce interpretable results. However, when a softer hammer tip with a longer contact time equal to $\mathrm{5,520}–\mathrm{6,840}\mathrm{\mu s}$ was utilized, the echoes from the pile toe were identifiable and consequently the length of the steel H-piles could be determined. These results show that SE/IR can be used to determine the depth of H-piles if a proper hammer tip is selected.

Underground reinforced concrete utility vaults play a vital role for the functioning of urban centers, providing space for all kinds of utility equipment. Underground structures are subjected to harsh environmental conditions that can impact their life and eventually trigger structural damage—potentially becoming hazardous to equipment and personnel carrying out routine inspections. A study was conducted to determine the main causes for deterioration in underground reinforced concrete structures observed during routine inspections in the southwest United States. Petrographic examinations of concrete samples cored from seven unique structures with significant damage showed that concrete carbonation has reached the reinforcing steel in some structures and there was evidence of minor sulfate attacks. Chloride ions were found at high concentrations, which had indications of being introduced through the concrete admixture. This is consistent with the practice of the precast industry around the 1960s–1980s to use calcium chloride admixtures to increase fabrication throughput. The presence of chlorides in the concrete matrix, coupled with gradual concrete carbonation, moisture, and oxygen, are the main causes of deterioration and damage observed in these structures.

The Taiwan Taoyuan International Airport (TTIA) has been in service for more than $40\mathrm{years}$. Some visible defects on the rigid pavement runway have been observed in recent years. In this paper, the authors aim to provide a practical and reliable method to improve the soil condition under the rigid pavement of a damaged airport runway. In addition, the authors present an inspection technique with excellent results, which could be evidence for the high efficiency of the proposed improvement work. The defects included surface settlement, slurry leakage through the gaps between panels (pumping), concrete panel cracks, and so on. In this TTIA case, the underpanel grouting method (UPGM) was selected to solve these problems. Grouting flow and pressure were well controlled, and the soil in the base course was successfully reinforced, with the gaps between the concrete panels and the aggregate base course filled. Under the application of the UPGM, 7,170 grouting holes were drilled, and $\mathrm{1,453,723}\mathrm{kg}$ of grouting materials were used to improve the soil conditions under the rigid pavement runway 23L-05R. For verification of its effectiveness, a ground-penetrating radar (GPR) and a falling weight deflectometer (FWD) were used. No noticeable deviation was observed in the GPR reports. Besides, the test results of FWD for concrete panel 71-6—the deflection ratios of the corner/center, which were tested before and after grouting—are 188% and 109%, respectively. All the test results show excellent efficiency of the UPGM.