Journal of Performance of Constructed Facilities

Unreinforced masonry (URM) buildings exhibited extreme vulnerability during past earthquakes, although these are shelters for a majority population in many earthquake-prone developing countries. Most of the current retrofitting techniques used for such structures are either expensive or require highly skilled labor or sophisticated equipment for implementation. On the other hand, the retrofitting technique proposed in this paper is economical and easy to apply. This paper aims at examining the performance of the retrofitting technique using polypropylene (PP) band. The displacement-controlled lateral deformation has been investigated experimentally. The monotonic load-displacement behaviors of a URM wall and the wall retrofitted with PP band are compared. It was found that the URM wall retrofitted by PP band improves the ductility and energy absorption capacity by three and two times, respectively. Performance of a full-scale masonry building retrofitted with PP band in Nepal during the last Gorkha earthquake of April 25, 2015, has also been presented in this paper. It was observed that the PP band–retrofitted masonry building survived, whereas many nearby buildings experienced severe damage and some of them collapsed. This study demonstrates the efficacy and practicability of use of PP band for improving seismic resistance of a URM structure.

High-rise reinforced concrete chimneys, used to expel waste gases, are commonly used structures in facilities such as chemical and power plants. Chimney structures located in marine areas are prone to corrosion. Regardless of the causing factors, corrosion causes the degradation of the strength of steel bars, creating a detriment to the safety of the chimney structure. A more severe situation is a corroded chimney structure that is subjected to other natural hazards such as strong winds and earthquakes. Very few documented research studies have evaluated the seismic performance of chimney structures under the combined hazards of corrosion and seismic loading. In this study, seismic fragility was used to compute the probability of damage to two corroded chimney structures of differing heights under near-fault ground motions. In the fragility analysis, the uncertainties of materials and ground motions were considered. Based on the numerical simulation results, fragility curves were generated. The results indicated that corrosion had a significant effect on the seismic performance of chimney structures. With an increased corrosion level, the probability of moderate damage, major damage, and collapse increased significantly if the intensity of the ground motion was greater than a threshold value. The threshold value was determined by the corrosion severity. Therefore, it is suggested to inspect the severity of corrosion and adopt measures for reinforcement to minimize the impact of that corrosion on the stability of the chimney, especially in areas susceptible to earthquakes.

This paper presents different strengthening techniques to eliminate some drawbacks associated with the available techniques. The considered strengthening techniques for the punching shear of RC slabs use the combined effect of internal single-leg stirrups and a double-skin steel assembly and properly anchored externally bonded glass fiber–reinforced polymer (EB-GFRP) sheets. Nine slab specimens divided into four groups are prepared and configured. It is found that the slab provided with properly anchored single-leg stirrups with a double-skin orthogonal steel assembly exhibits the most efficient technique among all considered techniques. This technique enables the slab to sustain a punching load about 1.69 times greater than that of the control unstrengthened slab. In addition, it triggers the slab to provide ductile punching failure showing strain hardening and softening plateaus. The experimental shear resistance of all strengthened slabs are compared with the design resistance stipulated by different design standards. It is concluded that the failure characteristics stipulated by German codes have the most rational results compared with those of the experimental findings.

Extensive damage to school buildings has been observed during past earthquakes in Italy, with the 2002 Molise earthquake resulting in the complete collapse of a school building, leading to numerous casualties. In this paper, data provided by instruments installed in a number of school buildings throughout Italy from both ambient vibration and triggered dynamic vibration following the 2016 Central Italy earthquake are compared with predictions of numerical models. This comparison of predicted and measured structural response characteristics is investigated to provide practicing engineers with further insight into and validation of the accuracy of typical modeling techniques compared with instrumented responses of numerous different building typologies subjected to different dynamic excitations. Initial comparisons demonstrate reasonable agreement between the numerically predicted modes of vibration and natural frequencies from ambient vibration measurements, with further numerical parametric studies exhibiting improved matching. Additional comparative analyses are considered to discuss the potential impacts on the seismic assessment of existing structures within a performance-based seismic assessment framework.

In order to reduce size and weight during the transport and installation stage, a steel box girder needs to be separated into asymmetrical thin-walled blocks with open sections along the transverse direction. However, the deflection and stress of the separate blocks are quite different from the complete bridge. The present method, based on the variational principle, takes the nonuniform arrangement of the shear braces and the temperature load into account, obtaining the theoretically exact solutions of generalized displacements and stress resultants. The present method can be used to design and optimize the shear brace arrangement and evaluate the performance with and without the reinforcement measures. Then, the proposed method is applied to two bridges with spans of 40 and 65 m to evaluate the effect of shear stiffness reduction and extreme temperature on the installation of the separate blocks. Reinforcement measures are proposed so that the bridges can be completed successfully. The stress results show good agreement with the field data.

The Hercílio Luz Bridge is an eyebar suspension bridge with a riveted girder built in 1926 in Brazil, in which severe fatigue damage was found after years of service. To provide guidance for rehabilitation of the bridge, a fatigue assessment is conducted under Eurocode fatigue load models to obtain stress ranges for the riveted and welded connections, as well as equivalent stress range and cumulative damage for the fatigue safety verification defined by Eurocode standards. Because the original design and construction of the bridge was completed per 1926 AASHTO requirements, for comparison, a fatigue assessment of the proposed rehabilitation is performed according to the more recent AASHTO recommended procedures. The floor-beam-to-truss and stringer-to-floor-beam connections, especially near the eyebar chain transition, are identified to be most prone to fatigue due to the occurrence of significant stress concentration. The predicted fatigue lives indicate that those connections may be weak and need to be strengthened. Analysis results reveal that the stresses under the Eurocode truck load are larger than those under the AASHTO truck load, due to larger gross weight and shorter total axle spacing of the Eurocode truck. In addition, the recommended number of cycles in both codes caused by a single passing truck is insufficient for connections under or near the loading position.

Progressive collapse of building structures is a field of research that has received considerable attention all over the world. Moreover, the vulnerability of conventional reinforced concrete (RC) frame buildings to structural failure triggered by the loss of key elements has been noted during recent years. Various guidelines such as unified facilities criteria (UFC) recommend that distinctive structural characteristics should be considered in the initial steps of structural design, so as to mitigate progressive collapse possibility of structures. Such guidelines state that including these features will provide for a significantly more robust structure and decrease the probability of progressive collapse while facing an uncommon loading situation. The structural redundancy index is among those features that can help the structural system to maintain its stability during abnormal loadings. It should be noted that, however, most provisions regarding progressive collapse in different guidelines include a general statement on alternative load paths, and there is rather non explicit mention of redundancy in such guidelines. In other words, the exact influence of this structural characteristic on progressive collapse is not clearly defined. This research highlights the importance of considering structural redundancy effects on progressive collapse of RC frame buildings and provides systematically identified information to better understand the way redundancy affects continuous collapse of structures. For this purpose, 16 finite-element models of RC moment resisting frames with different structural configurations were designed according to the provisions of ACI-318 and modeled in OpenSees. Subsequently, several damage scenarios (both in plan and elevation) were investigated to identify the ability of structures to resist progressive collapse under different circumstances. Numerical results were then compared and the effect of redundancy on progressive collapse of RC structures was clearly quantified. Finally, several predictive graphs were proposed to estimate the response of RC frame structures under progressive collapse.

New carbon emission requirements have brought about high demand for the retrofitting and strengthening of structures in power generation plants in order to accommodate the installation of pollution control devices. A typical form of such a retrofitted structure is a hybrid RC–steel frame with specific irregularity features. This paper presents the seismic performance evaluation of a representative irregular RC–steel hybrid frame formed by the vertical combination of a newly added steel frame and a preexisting RC frame. The prototype structure originates from a real retrofitting project, and the evaluation is carried out numerically by creating six variants of the hybrid frame retrofitted with different strengthening strategies on the RC frame using nonlinear finite-element modeling. The seismic performance of the hybrid frame structures is comparatively assessed in terms of roof displacement, story drift ratio, residual displacement, and hysteretic energy ratio when subjected to a group of selected earthquake ground motions at different intensity levels. The results show that among the three main types of retrofitting schemes, strengthening the preexisting RC frame with shear walls appears to be most effective in limiting roof and interstory drifts. Strengthening the preexisting RC frame at the local member level tends to be the least effective strategy. Overall, retrofitting the hybrid structure with steel bracings is deemed to be a more robust solution, both in terms of controlling displacements and enhancing hysteretic energy dissipation capacity.

Welded hollow spherical joints (WHSJs) are widely used in reticulated shell structures. WHSJs inevitably experience corrosion in their service life that significantly reduces their loading capacity, thus negatively affecting structural safety. A series of nonlinear numerical analysis is performed to investigate the effect of corroded location and size, yield strength of material, and corroded thickness on the compressive capacity of WHSJs. Two types of corroded shapes are investigated. Results indicate that corrosion located in different places has a distinct influence on the compressive capacity of WHSJs. Compressive capacity is significantly reduced when corrosion occurs at the WHSJ surface.

The Enhanced Fujita Scale (EF5) tornado that hit the city of Moore, Oklahoma on May 13, 2013 caused over $2 billion in damages and tragically claimed the lives of 25 individuals. Briarwood Elementary School and Plaza Tower Elementary School were both subject to extreme damage due to the May 13, 2013 tornado. As a result of this damage seven fatalities occurred at the Plaza Tower Elementary School. This large loss of life and extensive building damage at both schools warranted a forensic engineering investigation. The goal of this investigation was to determine if structural damage and fatalities could have been reduced. To evaluate the failures and failure mechanisms that were observed in both schools, with the purpose of determining structural inadequacies and proposing design, fabrication, and construction practices to create a more robust system. This investigation identified numerous shortcomings that might have reduced the structural damage and potentially the loss of life. The findings of the forensic investigations and a discussion of the structural shortcomings are presented in this paper.

The understanding of the complex behavior of reinforced concrete elements in situ would be aided if distributed strain measurements were captured during load tests, potentially leading to more accurate assessments and load ratings, and optimized future designs. This research investigates the use of distributed fiber optic sensors (FOS) to monitor three beams in a newly constructed RC building during a load test. It is the first case where an FOS technique capable of monitoring distributed strains, distributed deflections, and crack widths simultaneously is implemented in the field. The FOS data captured inflection points, moment transfer at the supports, crack locations, and crack openings. The FOS also captured deflected shapes, enabling maximum deflections to be determined without prior knowledge of where they would occur. Lastly, the measured results from the load test were compared to design model predictions for each element.

The reasonable damage evaluation method for tunnel structure can be used to determine the overall safety state of the tunnel structure and can help to establish the maintenance plan of the tunnel structure. As a fuzzy system, the evaluation process of tunnel damage has the characteristics of randomness and fuzziness. Traditional tunnel damage evaluation methodologies do not account for the fuzziness and randomness of the system. Therefore, this study puts forward a visual evaluation method based on cloud theory for evaluating tunnel damage. Damage evaluation for a shield tunnel section of Changsha Metro Line Two in China has been taken as a case study. This method effectively considers the fuzziness and randomness of the evaluation system, improves robustness of the results of the structural damage evaluation, and is a simple and visual method.

Water inrush events in tunnels are geological hazards that pose a special engineering problem for tunnel construction in water-rich areas. To clarify the engineering background and hydrogeological conditions of water inrush in tunnels, this paper investigates and analyzes three incidents that occurred during the Jiaoxi River Tunnel Project. It analyzes the construction unit’s successful response to these events, presents their technical data, summarizes some practical high-value technology, and analyzes the mechanism of water inrush both qualitatively and quantitatively. It is found that the water source was the Jiaoxi River, and the water inrush channel was the concentrated leakage channel between the river and the tunnel. The prevention of water inrush is necessary for the excavation of tunnels that are prone to water inrush. In the event of a water inrush, plugging grouting is the most efficient water inrush treatment program. If grout plugging is to achieve better results, it must first fill the water inrush channel as completely as possible. Additionally, a distributary decompression holes—grouting posttreatment scheme is the improvement of the first two processing techniques, which deserves to be applied and popularized in practical projects.

With the extending of existing networks of metro systems, existing subway tunnels are more and more commonly undercrossed by new underground tunnels. Excessive deformation and even damage may occur in existing subway tunnels due to the influence of new tunnel construction. This paper studies a case of two existing subway tunnels undercrossed by four closely spaced tunnels in Shenzhen. The displacement of the existing tunnels, the soil pressure, and the bending moment of the new tunnels are monitored. Considering the multiple soil disturbance, a three-dimensional numerical model is established for the analysis of tunnel settlement induced by multiundercrossing. The calculation results match well with the measured tunnel settlement data and the accuracy of proposed numerical approach is verified. Compared with the vertical displacement of the existing tunnels, the horizontal displacement is less affected by new tunnel construction underneath. The vertical displacement profile of the existing tunnels displays V, U, and W shapes, and the position of maximum displacement always shifts toward the new shield tunnel. Affected by the expansion of the disturbed area in the soil, the construction of two or more tunnels close to each other will lead to the increase of the bending moment of the new tunnels themselves.

This paper presents the data collected from the inspection of 105 Portuguese flat roofs. The inspections were based on a system of inspection, diagnosis, and rehabilitation created and validated previously for flat roofs. The use of this system increases the objectivity and effectiveness of an inspection and supports the inspection of flat roofs. The use of flat roofs is gaining momentum in the construction sector worldwide, and there is little information concerning the correlation among the most common types of anomalies, their most probable causes, applicable diagnosis tests, and the most suitable rehabilitation techniques. The information gathered during the field inspection of 105 flat roofs allowed the validation of the proposed inspection system and the determination of the most common features that can occur in this type of roofing system, as well as their correlation with the materials, characteristics, location, and position on the roofing system. The data analysis of the information gathered aims at helping designers, end users, and inspectors as a decision-basis tool regarding this roofing system, and is presented in various charts in order to facilitate their interpretation and help identify the most conditioning parameters in the performance and durability of this type of nonstructural system.

Structures subjected to distress by expansive soils generally show cracks of various types. These cracks are frequently used as an excuse to adopt nonrealistic decisions in construction practice. It is quite common to opt for structures demolition or expensive retrofitting for just shown cracks and nonsignificant differential settlements. The influence of repeated wetting and drying on the swelling parameters is of concern when justifying such decisions. Expansive formations are inundated by periodic rainfall and storms or other sources. This study is aimed at investigating the geotechnical properties and parameters for an area known of being of serious hazard to buildings and infrastructure projects. This research study is conducted for Al Ghatt clay from Saudi Arabia. Swelling clays supporting superstructure loads of 50, 100, and 200 kPa as contact pressures were subjected to four cycles of wetting and drying. The compressibility and swelling profile were investigated for each stress level and cycle of wetting and drying. The main geotechnical parameters including the swell pressure and the swell potential were measured. The compressibility index and hydraulic conductivity were also computed for all cycles at different level of stresses. Repeated cycles of wetting and drying resulted in reduction of swelling pressure as well as the swell potential by more than four times. Conversely, the variations of the compressibility index were insignificant and the reduction in the hydraulic conductivity was also marginal. A building subjected to serious cracking and movement in the region was monitored over a 1-year period to observe the influence of wet and dry season on the size of the observed cracks. The outcome of this study can encourage engineering communities and contractors to consider observing the structures for a second and third cycle of wetting before choosing to demolish an affected structure.

Social housing patrimony requires reliable management during its service life that includes refurbishment, maintenance, and conservation plans to maintain buildings’ durability, quality, and performance. Refurbishment actions intend to achieve functional performance parameters equivalent to those currently required, which are necessary to choose appropriate solutions for each situation but, above all, with high durability. An inspection and analyses of a social housing neighborhood was carried out that aimed to assess the durability of refurbishment actions that have been implemented in different phases. The degradation assessment of facades, glazing, and indoor areas using the failure mode, effects, and critical analysis (FMECA) and Mosler methods was carried out. Degradation curves of the different assessed elements were outlined. To meet the expected quality, durability, and comfort requirements, a conclusion was reached as to the most important refurbishment solutions that must be developed and implemented to achieve the predictable durability, resistance to climate actions, and reduced need for maintenance actions.

Reconnaissance teams are charged with collecting perishable data after a natural disaster. In the field, these engineers typically record their observations through images. Each team takes many views of both exterior and interior buildings and frequently collects associated metadata that reflect information represented in images, such as global positioning system (GPS) devices, structural drawings, timestamp, and measurements. Large quantities of images with a wide variety of contents are collected. The window of opportunity is short, and engineers need to provide accurate and rich descriptions of such images before the details are forgotten. In this paper, an automated approach is developed to organize and document such scientific information in an efficient and rapid manner. Deep convolutional neural network algorithms were successfully implemented to extract robust features of key visual contents in the images. A schema is designed based on the realistic needs of field teams examining buildings. A significant number of images collected from past earthquakes were used to train robust classifiers to automatically classify the images. The classifiers and associated schema were used to automatically generate individual reports for buildings.

The conventional curing methods for cement concrete pavement have been frequently criticized for their high levels of water consumption, high labor intensity, high cost, nonuniform curing quality, and other problems. In an attempt to solve these problems, the research of this paper, on the basis of some concrete pavement construction projects and some concrete pillar construction projects in China, explored the development of a new type of curing membrane from controllable high polymer materials for concrete curing that helps to save water and retain moisture. This curing membrane was developed with a new type of controllable high polymer material as the interlayer material, with a specialized plastic membrane as the carrier, and based on the concrete hydration principle as the theoretical background. In the research of this paper, a series of tests were done to measure the temperature and relative humidity of concrete cured using different methods. Furthermore, the strength, carbonization depth, and cracking of concrete slabs under different types of curing were also tested. The results indicated that (1) the use of the new-type water-saving and moisture-retaining membranes to cure concrete for 28 days could retain the surface humidity of concrete up to more than 90%; (2) microcracks of concrete slabs during summer construction were reduced by the combined use of a curing agent and the new-type water-saving and moisture-retaining membrane; and (3) compared with no curing at all, carbonization depth of concrete cured by the new-type curing membrane for 90 days was reduced by 60% while the concrete strength increased by 8.6 MPa, up to 51.6 MPa.

A combined analytic hierarchy process (AHP) method, Delphi method, and cloud model, i.e., a cloud clustering–based group decision method, is proposed. The risk probability and risk loss of the main risk factors are scored by experts. A backward cloud generator is used to calculate the digital characteristics of the sample from the experts’ scoring. A forward cloud generator is used to generate the cloud droplets according to the scoring samples from the experts. An iteration method is approved to quantify the coherence. Introduction of the expert authority, group decision risk probability, and risk loss can be obtained based on the cloud model. Similarly, the group decision weight of risk resources can also be obtained by the cloud-clustering group decision method. According to the risk resource weight, risk probability, and risk loss, risk level can be determined based on the risk judgment matrix. The study results show that the risk level of the example cable-stayed bridge is Level II, which is very similar to the computation achieved by a method derived from the current safety risk assessment guide in China. However, cloud clustering can ensure higher coherence for the samples. Consequently, the risk evaluation result will be more stable. The real bridge example and comparison analysis show that the cloud-clustering group decision method is reasonable and can objectively estimate the bridge risk.

With the rapid expansion of the high-speed railway (HSR) network in China, some new lines must be constructed near or across existing HSRs, which will likely have an effect on the operational safety of the HSRs. The existing HSR bridges are highly sensitive to the construction influence of the adjacent piles, and a small displacement of HSR bridges may cause high-speed trains to derail, with disastrous consequences. Consequently, pile construction adjacent to HSRs should be accompanied by an appropriate method to mitigate its detrimental effects on HSRs. The Benoto method is considered to be environmentally friendly and economical because of its fast construction efficiency, low slurry discharge, and no risk of shaft necking. Few studies have been done investigating the influence of Benoto pile construction on adjacent HSR bridges. This study fully explores the construction influence of Benoto piles on neighboring HSR bridges. Specifically, the Nanjing S3 Metro Line project in China serves as the test bed, and a comprehensive field monitoring system was installed to measure soil displacement and stress as well as HSR bridge pier displacement. Several observations can be made on the basis of this study: (1) the variation in soil stress and lateral movements is slight when the distance between the pile and the soil exceeds 18 m; (2) the settlement of the surrounding soil is especially obvious when the steel casing is pulled out; and (3) the settlement of soil at the bridge site and the horizontal displacements and inclination angles of existing piers do not exceed the corresponding warning, which indicates the safe operational condition of the adjacent HSR during the construction of Benoto piles. The findings of this work may provide useful guidance for the design and construction of piles adjacent to in-service HSRs.

In this study, the Icy Springs Bridge, located in Coalville, Utah, was load-tested to quantify the effects of significant deterioration on its live-load behavior. Visual inspection and load testing of this double tee structure indicated a severely deteriorated deck, undamaged girder stems, and partially effective transverse connections at the longitudinal joints. At the time of testing, the bridge was load-posted at 35.6 kN (total gross vehicle weight) with a maximum speed of $8\mathrm{km}/\mathrm{h}$ due to conservative rating assumptions. After a detailed analysis, a truck that was 7.5 times the posted weight was used for a load test. A shell-based finite-element model was created that used variable spring elements to model the deteriorated flange-to-flange connections, which accurately replicated the behavior of the bridge from the load test and validated the modeling technique. The model was used to perform a parametric study, using idealized flange-to-flange connections, to compare the calculated girder distribution factors to the finite-element model–estimated girder distribution factors, and poor agreement was found ($R^2=0.449$ and 0.237 for moment and shear, respectively). A multivariable linear regression analysis was used to develop moment and shear girder distribution factor equations for double tee bridges similar to the one investigated in this study, with a much better correlation of $R^2=0.86$ and 0.83 for moment and shear, respectively.

The poor seismic response of gravityload-designed reinforced concrete (RC) frames with a soft story can be effectively controlled by using metallic dampers as passive energy dissipation devices. However, the absence of adequate large-scale test results and numerical tools for the accurate prediction of the seismic response of strengthened RC frames impedes their application in construction practice. This study presents a strengthening technique for the RC frame with a soft story using combined metallic yielding devices. Pseudodynamic testing of a two-story large-scale test specimen has been conducted to investigate its seismic response under varying amplitudes of a selected ground motion. A quasistatic cyclic test has been conducted to evaluate the collapse resistance of the strengthened specimen. In addition, a numerical model using computer software OpenSees has been developed to predict the seismic response of the strengthened RC frame. Both cyclic pushover and nonlinear dynamic analyses have been conducted to predict the seismic response and the collapse resistance of the strengthened specimen. The results of the numerical study matched reasonably well with the experimental findings.