Journal of Performance of Constructed Facilities

Ground Penetration Radar (GPR) is now a mature technology with various applications for scanning different types of constructed facilities including underground utilities and structural systems. Several models of GPR scanners are commercially available and selecting the optimum machine for certain applications is a significant decision-making task for practitioners and researchers. As a result, there is a demand for reviewing the latest states of practice and research on applying GPR technologies to assist practitioners and researchers with their scanning tasks. This paper is an attempt to address the aforementioned issue through conducting an in-depth review on existing models of GPR scanners as well as a comprehensive review on undergoing research activities in this area. The results of this study are summarized in five sections: The first section provides a brief overview on the general structure of a GPR scanning system. The second section reviews the commercially available GPR machines plus the advantages, limitations, and specific application of each model. The latest state of research for scanning and labeling constructed facilities using GPR scanners is presented in the third section. The next section briefly reviews the postprocessing steps required to convert the raw data obtained from GPR scanners into rich information about the desired objects. Finally, the results of a comparative study conducted by the authors to evaluate the performance of two popular models of GPR scanners (StructureScan Mini XT and Handy Search NJJ-105) in scanning a number of structural elements (concrete walls, columns, and slabs) as case studies are presented.

The comfort of pedestrians on a footbridge is a rather complex problem that has been discussed for a long time. Vibration acceleration is generally accepted as the main controlling factor that influences pedestrian comfort. However, no consensus has been reached regarding which acceleration-based parameters should be used as an index for assessing comfort. Only simple comfort limits, rather than specific relationships between comfort and the corresponding indices, are currently available for assessing the vibration serviceability of a pedestrian bridge. In this study, the vibration acceleration of 21 pedestrian bridges in Beijing, China, were recorded under different service conditions, and questionnaire surveys on pedestrian comfort were conducted. The acquired testing and survey results were utilized to analyze the correlation between pedestrian comfort and bridge vibration. A procedure for assessing the vibration serviceability of pedestrian bridges considering pedestrian comfort is proposed based on the relation between pedestrian comfort and the maximum footbridge acceleration.

This paper presents an assessment of postfire damage of a RC factory building. The fire was limited to the ground floor; thus, the structural elements on the ground floor were fire damaged. Also, some relative displacements were observed at the expansion joints, and long wall cracks were observed on other stories. During the visual assessment, typical fire damage was observed (e.g., spalling, netlike cracks, crumbled plaster, bared or visible reinforcement, and crumbled aggregates). Also, some explosive and thermal expansion–induced damage was observed in and out of the fire-damaged areas. To evaluate the effects of the fire on the concrete, spectrophotometer and compressive strength tests were performed on concrete specimens taken from the building. It is concluded that elevated temperatures due to a fire can cause damage in the fire region, and that it can affect the overall stability of the structure.

Tunnels are generally built under trunk roads (where traffic conditions are complex and heavy) in order to share the load of urban road systems. The construction of tunnels has significant effects on the surrounding environment, especially in connection with nearby bridges, since it may cause soil loosening, ground deformation, and bridge pile settlement. Traditional methods, such as fuzzy set, fault tree analysis (FTA), artificial neural network (ANN), are inefficient and inaccurate when it comes to analyzing risk magnitudes or probabilities in a dynamic environment. To fill this gap, this paper, with the aim of predicting, monitoring, and diagnosing risk factors for tunnel-induced damage, provides a new framework that integrates the advantages of rough set (RS), cloud model (CM), and Bayesian network (BN). A RS approach is used to handle the vagueness and uncertainty and reduce redundancies for improving the efficiency of the evaluation process, CM is employed to discretize continuous attributes without changing their distinguishing characteristics, and BN is utilized to train mess data with a reasonable inference mechanism and update the risk magnitude with given evidence. To model the risk network of the tunnel-induced bridge damage, 14 critical influential factors are identified. A real tunnel project that crosses an overpass of expressways in China is used as a case to prove the applicability and feasibility of the proposed approach. Results verify that the proposed hybrid BN approach can be used to predict, supervise, and diagnose the risk before, during, and after tunnel construction. This research contributes to (a) the state of knowledge by providing a novel risk analysis approach that is capable of handling fuzziness, uncertainty, and dynamics in factor characterization; and (b) the state of the practice by providing insights into a better understanding of how to predict, control, and diagnose risks under given observations.

This paper investigates the use of the nonlinearity of acceleration measurements to bridge damage identification. Delay vector variance (DVV) method is applied to analyze the measured dynamic responses and to identify damage to bridges under moving vehicle loads. First, the DVV algorithm and its quantification method, the vehicle-bridge coupling system, and source of nonlinearity in dynamic responses are introduced. The feasibility of this damage identification method is theoretically explained. Then numerical studies on a simply supported beam under moving vehicle loads are conducted to investigate the influence of different crack models in identifying damage. Finally, experimental studies are carried out to verify the applicability and effectiveness of the proposed method. The results show that the method can be used to identify concrete cracking damage in simply supported beam bridges under moving vehicle loads. The method has certain robustness to environmental noise, and damage identification results are not sensitive to the location of sensors.

For further improving the seismic design of steel-reinforced concrete (SRC)—RC frame structures, a two-step seismic calculating method is proposed as a supplement to the current Chinese standard for structural seismic resistance design. In Step 1, internal structural forces are calculated by the modal response spectrum method and limited structural members’ internal force in the elastic level when the structure suffers frequent earthquakes. In Step 2, structural deformations are analyzed by pushover according to the moderate earthquake’s demand spectrum and controlled in a repairable level. A 20-story and $5\times 5$ span initial frame structure whose columns are fully SRC and two SRC-RC frame structures that are replacing SRC columns of the initial frame structure in the upper stories by using RC columns were designed according to this two-step seismic calculating method. These three frame structures were analyzed using dynamic time history analysis by inputting rare earthquake waves. The research results show that all three structures can satisfy the safety requirements under rarely observed earthquakes. Moreover, some design suggestions for SRC-RC frame structures were provided according to failure modes and seismic performance of these three frames.

Pile-supported river bridges continue to collapse after most major earthquakes in the event of liquefaction. The identified failure mechanisms of piles in liquefied soil are (1) bending failure due to inertial loads of the superstructure and kinematic loads due to the lateral spreading of soil; (2) shear failure due to shear loads; (3) buckling instability failure due to vertical loads and associated imperfections; (4) settlement failure due to loss of effective stress in the liquefied zone; and (5) failure due to the effects related to elongation of the natural period of the piers (also referred to as dynamic failure). This paper revisits the collapse of Shengli Bridge (Tangshan, China) (due to the 1976 Tangshan earthquake) and Panshan Bridge (Panjin, China) (due to the 1975 Haicheng earthquake) based on the aforementioned failure mechanisms. It has been concluded that pile-supported bridges in liquefiable soil can collapse due to each of these five failure mechanisms or due to a suitable combination thereof. It is therefore quite imperative to take all the failure mechanisms into consideration when designing pile foundations in liquefiable soil. The simplified calculation procedure presented in this paper can also be used to carry out the design of bridge piles in liquefiable soil.

Karst development and the deformation response of erosive rocks significantly influence the stability of cutting slopes. In this research, cutting slopes for high-speed railways was investigated in karst areas, and four representative points with various degrees of karst development were chosen to examine the rock response by applying rectangular rigid bearing plate tests. The displacement distribution of the rock under the plate was analyzed using elastic half space model theory. Results corroborate that, although the erosive rock experienced loading–unloading cyclic loading, the envelope diagram was upward convex. When a relatively lower load was applied, the slope of the $P\text{-}w$ curve was steep, and the rock deformation was smaller. As the load increased, the slope of the $P\text{-}w$ curve became moderate; under the same load condition, rocks with a high degree of karst development had high deformation and deformation modulus values. However, rocks that were less influenced or unaffected by karst development had minimal deformation. At the same point under the bearing plate, increasing the load enhanced the displacement of the point, and the deformation value became high as the degree of karst development strengthened.

In this study, a numerical investigation into how the shear wave velocity profile affects the seismic performance of tall buildings and foundations was carried out using FLAC3D software. The in situ soil profile and equivalent average soil profile, which reflect the actual soil shear wave velocity profile and the corresponding uniform time-averaged soil shear wave profile based on the actual profile, respectively, were studied. Overconsolidated soil near the ground surface was considered in the in situ soil profile. A 20-story building supported by an end-bearing pile foundation was designed and simulated. A fully coupled nonlinear dynamic analysis was carried out in the time domain to evaluate the seismic response of the structure and foundation system under strong earthquakes. The variations of the interface parameters with depth around the piles were considered according to the variations in the stiffness of surrounding soil with depth in the numerical model when the in situ soil profile was used. The predicted shear forces, maximum lateral deformation, and maximum interstory drifts of the building are presented and discussed, as are the maximum shear forces, maximum bending moments, and the maximum lateral deformation of the piles. The results indicate that the use of an actual shear wave velocity profile instead of an equivalent average profile gives design engineers the opportunity to optimize their design and achieve cost-effective solutions.

Mechanically stabilized earth (MSE) walls are extensively used in civil infrastructure projects, particularly in areas with tight right-of-way constraints. Traditional geotechnical design of MSE walls includes internal and external stability checks. The long-term performance of the entire MSE wall system is dependent upon proper construction of the system of geotechnical and structural components. Excessive deflection of the concrete facing panels is usually indicative of construction quality control problems, but these have been difficult to easily asses in the field. This paper proposes a methodology using high-resolution terrestrial laser-scanning technology for field measurements of out-of-plane offsets and angular deviations for MSE walls with precast concrete panels. A MSE wall constructed in the state of Indiana is used to illustrate the proposed methodology, where panel-to-panel out-of-plane offset was in the range of $-10.3$ to 10.9 mm for 90% of the observations (range between the 5th and 95th percentile values). In addition, the angular deviations were $\le 1°$ for 90% of the observations. Spot checks comparing laser scan data and manual measurements for out-of-plane offsets were in the 1–2 mm accuracy range.

In this paper, a new method is proposed for the strengthening of a T-girder bridge with a transverse connection. The proposed connection consists of a top plate, two diagonal braces, one horizontal brace, and two brackets. A series of experiments and simulation were carried out to study the mechanical properties of a T-girder bridge strengthened with transverse connections. The main parameters included the installation height and number of the transverse connections on the bridge as well as the loading patterns. The simulation results show that the strengthening effect is better when the transverse connections were installed at the bottom of the girders than at the neutral axis. It is revealed that the exterior girders are the control girders and their midspan cross sections are the control cross sections. That is, the midspan of the exterior girder is the most unfavorable loading position. The experimental results show that the proposed strengthening method can reduce 27.6% of the maximum deflection with the proposed transverse connections installed at quarter points under the most unfavorable loading position. Moreover, the transverse connections serve to improve the load distribution of a T-girder bridge as well. Thus, a favorable strengthening effect is demonstrated for a T-girder bridge with the proposed transverse connections. Some design suggestions are also given for practical engineering strengthened with the proposed transverse connections.

The generation of rock bursts is closely related to overburden movement. Particularly in the condition of a hard and thick overlying strata in deep mining, the impact of a rock burst is even more prominent. A special geological mining condition of the giant thick overlying conglomerate of Huafeng mine was used as the background for this study, and the influence of overburden characteristics on rock bursts was discussed. Due to the development of large-scale bed separation in the lower part of the conglomerate, the conglomerate layer was in both relatively stable and unstable states, and the mechanism of a rock burst under these two conditions was studied. According to surface observations and downhole microseismic monitoring, the conglomeration movement was divided into five stages. The law of rock burst occurrences in each stage was analyzed, which showed that the occurrence of rock bursts periodically changes with variations of the conglomerate movement stage. Combined with the application of bed separation grouting, it has been shown that the risk of downhole rock bursts can be reduced by suppressing the movement of conglomerates through grouting technology.

For steel-reinforced concrete (SRC)–reinforced concrete (RC) hybrid frame structure, damage always appears in the transfer position of the section configuration from SRC to RC. To explore the failure modes and damage processes of vulnerable stories in SRC-RC hybrid frame structures, two SRC-RC frames, one only composed of the SRC-RC hybrid frame and the other filled with masonry walls, are tested quasi-statically. The damage index of the whole structure and structural members is calculated using the Park-Ang model. Furthermore, a weighted combination method to calculate the entire frame damage using the local members’ damage indexes is proposed in this paper based on redundancy theory. Finally, the weighted combination method is well matched with the Entire method according to the testing result. According to damage distribution for each structural member in vulnerable stories, some strengthen methods and construction measures are suggested.

A simulation-hybrid approach that incorporates artificial intelligence (AI), simulation, and experiment components is proposed to cope with the excessive surface settlement induced by tunneling excavation for the discovery of the optimal strategy. The AI component aims to predict the tunnel-induced surface settlement to detect whether the estimated settlement exceeds the control standard. The simulation component aims to investigate the complex tunnel–soil interaction for benchmarking multiple response alternatives. The experiment component aims to validate the effectiveness of the identified optimal response strategy in a natural setting environment. A shallow tunnel case in China is used to testify the effectiveness of the proposed approach. Results indicate that (1) the continuous grouting scheme for ground treatment is identified as the optimal strategy to deal with the excessive settlement potential and (2) the implementation in the actual practice further confirms that the continuous grouting scheme can reduce the surface settlement by 48.75%. The novelty of this approach lies in (1) the body of knowledge by developing a proactive approach to simulate, predict, and mitigate tunnel-induced settlement under uncertainty and (2) the state of practice by providing new insight into the control of excessive settlement potential with high accuracy and reliability.