Journal of Performance of Constructed Facilities

This paper summarizes the different activities undertaken in order to identify the main causes of the collapse of the Space Building, a 27-story reinforced concrete framed building in Medellín, Colombia. Site investigations, field and laboratory tests, and a detailed analytical work including structural analysis under different considerations were carried out. The main cause of the collapse was associated with the deficient structural capacities of the columns of the building in relation to the dead and service loads imposed at the time of the collapse. The occurrence of high differential settlements, the high compressive stresses in main columns, the repair works that were carried out minutes before the collapse, and the probable shear failure of beams and compressive failure of partitions walls during repair works were identified as probable secondary causes and detonating factors of the building collapse. The authors of this investigation considered that if the building had been designed adequately using the Colombian building design codes available at that time, it would not have collapsed, even if most of the aforementioned detonating events had occurred.

An accurate correlation model between thermal loading and deformation is required for facilitating a reliable deformation-based condition evaluation in bridge service periods. In this paper, a general approach for modeling closed-form thermal correlation of deformation based on monitoring data is proposed and applied in a long-span arch bridge. First, samples of all available thermal variables and deformation induced by thermal loading are prepared by averaging preprocessed monitoring records at a 10-min interval. Then these available thermal variables are reduced to several predominant thermal variables, each of which represents a cluster of thermal variables with statistical similarity and has the strongest relationship with the thermal deformation in concern. Finally, the model of thermal deformation is formulated as a weighted sum of fitted functions of predominant thermal variables. The weighted coefficients are calculated by the back-propagation neural network technique combined with the mean impact value method and the fitted functions are estimated by the nonlinear least-squares method. The proposed approach is applied to 1 year of monitoring data obtained from a sophisticated structural health monitoring system deployed on the Jiubao Bridge. The proposed method is validated and a closed-form thermal correlation model of vertical deformation in the Jiubao Bridge is established.

This paper presents a quantitative and qualitative study of deficiencies in the design of brick façades, by identifying the most common mistakes by analyzing projects’ technical specifications. To this end, 64 brick façade projects, produced in Spain between 2000 and 2013, were analyzed. In most cases, of the 29 parameters studied, 45% correspond to a lack of definition in the designs and 34% to a lack of data. The most frequent issues are the lack of detail in thermal bridges and the lack of indication of the characteristics of permeability, water sealing, and resistance of the exterior carpentry. Only 13% of the monitored projects were of high quality (8), 66% were of medium quality (42), and 22% were of poor quality (14). Furthermore, a methodology is presented to identify the aspects of the projects that will lead to nonquality costs during the service life of the buildings, and a tool is proposed to allow minimizing errors in the design stage, so as to avoid them in subsequent works. It is shown that the use of this methodology constitutes a suitable preventive strategy, directly improving the infrastructure’s sustainability by preventing between 65 and 75% of damages in façades.

This paper presents an experimental investigation of the structural performance of typical Tibetan timber beam-column joints (BCJs) under vertical load in order to study the effect of queti inclination on the load effects. Five full-scale test specimens are fabricated including one normal joint and four specimens with different queti-inclination angles. The failure modes of components, the evolution of failure of the whole joint with increasing angle of queti inclination, and the load-transferring mechanism of the typical Tibetan timber BCJ are studied. Furthermore, an experimental model of the load-displacement relationship is obtained from nonlinear regression of the experimental data. The structural performance of the joint in terms of the stiffness, yield load, ultimate load-carrying capacity, and their degradation with respect to the queti-inclination angle is investigated. It may be concluded that the queti inclination has a great effect on the deformation caused by floor load. This study provides reference for the safety evaluation and preservation of Tibetan cultural heritage structures.

This paper focuses on panel zone effects on the progressive collapse resistance of steel frames. A corner or middle column of the structure was immediately removed from the model according to General Services Administration (GSA) guidelines, and the progressive collapse of the frames was evaluated by nonlinear dynamic analysis. Two types of structural systems were designed for the building: (1) special moment frames in both directions, with box-section columns; and (2) special moment frames in one direction and special concentrically braced frames in another direction, with I-section columns. First, the panel zone model was verified by an experimental result, showing excellent correlation with the experiment. Then it was applied in the structures. The results show that considering panel zone in the structure with I-section columns intensify the progressive collapse, especially when removing a corner column. However, this influence is not considerable for the structure with box-section columns. Therefore, in general, the panel zone effect must be considered for progressive collapse. If shear resistance of panel zone just satisfies minimum criteria presented in building codes, its deformation should be considered in progressive collapse resistance of structures, and using center-to-centerline dimensions is not safe.

Although the column-drift method is commonly used for constructing a shallow underground metro station, there are few comprehensive field monitoring studies to investigate the mechanical behavior during complicated construction procedures. This study investigates the stress and deformation characteristics of a single-floor three-span metro structure built by the column-drift method in dry sandy ground based on the field case of the Great Wall Qiao Station in Shijiazhuang Metro Line 1. The excavation started at the two pilot tunnels to erect the two columns, which then served as support structures for the middle drift and then the two side drifts, which were excavated last. By comparing the results obtained from field monitoring and numerical analysis, it was found that the crown settlement and convergence of the primary and temporary supports mainly occurred during the excavation of the lower parts of the top caverns in both the pilot tunnels and side drifts. The crown settlement of the middle drift was small due to the support of the early columns and longitudinal beams in the pilot tunnel. After the primary and temporary supports were closed, the deformation of the structure did not develop, suggesting that the temporary structure should be closed as soon as possible. When the middle and side drifts were constructed, the temporary supports were dismantled, resulting in an obvious increase in the stress of the remaining primary supports. Thus, the demolition length of the temporary structure per cycle should be strictly controlled. The surrounding load was partially transferred to the secondary lining in the side drifts after its final placement, which resulted in a decrease in the stress of the remaining primary supports. Once the middle drift was excavated, the top of the monitored column moved toward the station center line. After the transversal temporary supports between the left and right longitudinal top beams were fixed with prepressure, the top of the columns turned back to the opposite direction and their movement increased after the crown supports of the middle drift finished. In the meantime, the stress difference between the two longitudinal beams became obvious. The tilting of the column roofs decreased after the two side drifts were simultaneously constructed. It was suggested that the temporary transverse supports and the symmetrical construction of the side drifts were effective measures in controlling the tilting of columns.

This paper studies the dynamic behavior of one of the oldest masonry arch bridges of the Iranian railway network, the Veresk bridge, located in the Mazandaran province of Iran. To do so, the writers developed an advanced three-dimensional (3D) finite-element model that incorporates all of the geometric complexities of the bridge. The obtained results show a very good agreement between the field test data and the 3D model. Due to the high computational costs associated with running the 3D model, a simplified two-dimensional (2D) model of the bridge was developed using Timoshenko beam elements and calibrated with the field test data and the 3D model. The results show that the 2D model has sufficient accuracy in capturing the dynamic behavior of the bridge. Therefore, an extensive parametric study is performed for inspecting the dynamic behavior of the bridge under the train speeds ranging from 25 to $350\mathrm{km}/\mathrm{h}$. It is observed that the serviceability and performance of the Veresk masonry arch bridge is not acceptable for speeds greater than $100\mathrm{km}/\mathrm{h}$, and the bridge experiences resonance when the train passes with the speed close to $200\mathrm{km}/\mathrm{h}$.

This study proposes a bridge safety evaluation process against seismic and flood hazards. Because uncertainties in the scours, seismic hazard, and structural performance for a given seismic excitation are inevitable and important, reliability analysis is adopted. A scour prediction equation for a bridge with a complicated foundation system is developed and a probabilistic scour curve is constructed to measure the risk of scours using the Monte Carlo simulation. The seismic hazard is measured using the probabilistic seismic-hazard analysis. A series of nonlinear time-history analyses are performed to determine the structural performance under different peak ground acceleration values. Specific software is used to build the finite-element model where the soil is modeled using a bilinear link. A plastic hinge is predefined to simulate the nonlinear behaviors of the pier and caisson of the bridge. The displacement ductility is used to measure the structural performance and to construct the fragility curve for various limit states. The Nanyun Bridge located in central Taiwan is selected as an example to demonstrate the proposed safety evaluation procedure. The results show that the probable scour depth of the Nanyun Bridge is from 3 to 5 m. The failure probability considering the floods and earthquakes is insignificant. A deterministic design value, considering both the hazards, is provided for a given reliability target (e.g., $\beta =3$) to help engineers in their present design processes.

Unreinforced compressed stabilized earth brick (CSEB) shell structures offer economic and environmental benefits that promote their adoption as an affordable housing alternative. Because these shells are unreinforced, designers normally apply methodologies such as thrust line analysis to ensure that internal force resultants remain within the middle third of the cross section (i.e., no tensile stress). Actions such as self-weight, wind, and asymmetric distributed loads are typically considered in design. Although a pure-compression design technique offers considerable safety against collapse initiated by the aforementioned actions, most structural damage (e.g., cracking) can be attributed to loads that appear to be regularly overlooked. In particular, extensive cracking caused by self-straining stresses (restraint of thermal and shrinkage movements) is observed in several dozen unreinforced masonry shells built in South Africa. The mitigation of cracks is important because they are the most common cause of a masonry structure’s failure to perform as envisaged. This is especially significant in adobe and CSEB shells because of the modest durability characteristics of these building materials. In this study, the causes of cracking in unreinforced shells are examined and, subsequently, the importance of self-straining stresses and concentrated loads is highlighted. The study demonstrates that unreinforced CSEB shells should be designed for a range of cracking factors. Several guidelines are proposed in this regard, which are particularly applicable in a low-cost setting, such as the use of white paint to attenuate large surface temperatures.

Utility managers and other authorities often rely on sewer structural condition prediction models for the effective execution of long-term and short-term sewer management strategies; however, it is challenging to predict the structural condition effectively because of the intrinsic uncertainties in modeling. In this research, a Bayesian framework is developed to predict the structural condition of sewers considering model uncertainties. Bayesian model averaging (BMA) techniques are used for identifying significant covariates for different sewers considering model uncertainties, whereas Bayesian logistic regression models are applied for predicting the structural condition of sewers. To validate the effectiveness of the proposed framework, the structural condition of 12,728 sewer mains of the wastewater network of the city of Calgary, Canada, is predicted. The results show that the BMA approach provides a transparent statement of the posterior probabilities to represent the effect of the significant explanatory covariates, and the performance of the Bayesian logistic regression model improves with informative priors.

Compared to research studies on the behavior and performance of reinforced concrete and steel structures, there is almost no information available in the literature relating to heavy timber structures such as timber pile bridges. With growing interest to expand the scope of structural designs to extreme loads from multiple hazards, the knowledge gap is expanding. In this study, the performance of a model bridge with timber pile substructures and a precast concrete superstructure was examined in a multihazard scenario involving three hazards: timber deterioration, earthquake, and tsunami loading. As a countermeasure to timber deterioration, a retrofitting strategy using fiber-reinforced polymer (FRP) composites was investigated. Material models for as-is timber piles and FRP-confined timber piles were derived based on experiments conducted on field-extracted specimens. The earthquake and tsunami events were simulated sequentially. The particle finite element method is used to conduct the tsunami simulation. Results show that even a modest level of timber deterioration can considerably affect the capacity of timber pile bridges under earthquake-tsunami loading. However, the FRP retrofitting technique considered in this study shows significant improvements can be achieved in terms of earthquake and tsunami capacity by strengthening a few selected timber piles.

Earth pressure on a retaining wall decides the sectional dimensions of the wall, and there have been several attempts in the literature to reduce the earth pressures on the retaining walls, by using techniques such as lightweight backfill and placement of compressible inclusions at the wall-backfill interface, to name a few. A retaining wall with pressure relief shelves, though discussed for several decades, is one of the least practiced techniques to reduce the earth pressure on retaining walls, mainly because of its complex behavior and lack of distinct provisions. One such wall was constructed in the populated area in Hyderabad, India, however, it failed after a few years. This failure has motivated the authors to study the behavior of these walls and to understand the associated mechanism involved in earth pressure reduction, as well as what caused the failure in the previously mentioned wall. The work reported in this study presents static force analysis and numerical analysis of rigid nonyielding retaining wall retaining a dry cohesionless backfill with pressure relief shelves performed using three-dimensional numerical analysis. A parametric study is conducted to understand the influence of width and position of relief shelves on the contact pressure below the base slab, surface settlement profile of backfill, deflection of relief shelves, and reduction in lateral earth pressure. The present study reveals that relief shelves can reduce lateral thrust on the wall up to 23%, compared to that of a retaining wall without a relief shelf. The static force analysis suggests that the width of relief shelves should be increased from top to bottom of the wall, for achieving maximum reduction of earth pressure. Moreover, it is also noted that maximum allowable width of the relief shelf at any height of the wall is a function of the width of the relief shelf lying above it.

The speed of vehicles on highways has increased due to improved driving environments. However, this increased speed has become one of the main reasons for collisions between vehicles and road barriers. Several fatalities have occurred recently in South Korea as a result of fragmentation due to the collision of a vehicle with a concrete median barrier. The current impact level of a concrete median barrier (CMB) is SB5-B (270 kJ). However, the impact level of the collision was estimated to be over SB7 (2,300 kJ). Inspired by this, many engineers agree on the use of improved CMBs to reduce the amount of concrete fragmentations due to vehicle impact. In the present study, several designs of CMBs have been presented and a numerical analysis was conducted to evaluate the impact resistance of CMBs against vehicle impact loadings. A new impact severity [SB5-B(20A)] was also proposed. Firstly, commercially available wire-mesh reinforcements and an increase in cross section were considered as design modifications under the proposed impact severity. In addition to this, a novel CMB, the High CMB (Hi-CMB) has also been introduced in this paper which has several shock absorbers without incurring any increase in construction cost. The newly developed Hi-CMB was evaluated by the developed collision model. It was found that the Hi-CMB with shock absorbers can reduce concrete fragmentation by 99% compared to the current type of CMB in South Korea. Shock absorbers generally activated and increased the impact resistance especially at high impact levels. As a result, an enhanced impact resistance, due to the addition of reinforcement, section expansion, and shock absorbers was obtained under SB5-B(20A). The mixed effects of those design modifications led to an effective design of CMBs against the impact loadings of heavy trucks.

As part of a major rehabilitation program in 1999–2004, several sections of the Arkansas interstate system were overlaid. Some of these sections experienced severe distresses (rutting and cracking), but the others performed well. The objective of the study is to evaluate the root causes of the poorly performing pavements. Consequently, historical data were analyzed and mechanistic tests were performed on collected core samples from existing pavements in order to establish correlations with parameters influencing the aforementioned distresses. The binder contents in good-performing, poor-performing, and medium-performing sections were approximately the same. Asphalt binders’ excessive aging, mixtures’ dust to binder content ratios, and in-place air voids of the poor-performing sections were found to be major causes of premature failures of the poor-performing sections. The findings of the study are expected to be a good pavement management tool for pavement maintenance actions.

Extreme winds such as tornadoes and hurricanes are relatively common natural hazards in the United States and can result in fatalities as well as damaging physical and socioeconomic infrastructure. Buildings are a critical sector within the built environment of a community and studying their performance under natural hazards is a major step for the risk and resilience assessment of a community. More than 80% of the total building stock in the United States and more than 90% of the residential buildings in North America are wood-frame construction; a construction type that is vulnerable to wind damage because they are light and typically are not engineered, only prescriptive in their design. Performance enhancement strategies for wood-frame residential buildings were investigated in this study by exploring combinations of roof coverings, roof sheathing nailing patterns, and roof-to-wall connection types. In this regard, a total of nine construction product combinations were considered. Further, recent changes to the wind standards were also explored. Specifically, the damage fragilities of five wood-frame building archetypes are considered for four damage states defined based on the performance of the building envelope, including roof coverings, doors and windows, roof sheathing, and roof-to-wall connections. The fragility curves are explained at the component level and then the building level for one archetype as an example, and the building fragility parameters are provided for all archetypes and for all construction product combinations. Comparison between fragilities developed using the last two versions of the wind standards are also presented. Then, an existing approach that amplifies the wind pressures in the wind standards to represent a tornado load is also compared. The fragility curves provided in this study can be used to represent residential buildings within a community for risk or resilience assessment/mitigation under hurricane or tornado loading.

For owners of aged buildings, considerable attention needs to be devoted to efficient facility management (FM) to extend building life and achieve life-cycle cost savings. The fundamental step in this is to identify the level of FM performance. Few studies have focused on the quantitative investigation of FM performance, and there has been minimal research on the methodology required to arrive at the optimal strategy. The purpose of this study is to present a systematic algorithm that allows FM practitioners to evaluate their performance in an objective manner. In addition, the authors have formulated a FM performance evaluation index in conjunction with the fuzzy synthetic evaluation method. The framework for this evaluation includes 12 critical success factors and 18 key performance indicators according to 4 balanced scorecard perspectives. A case study on a commercial office building was conducted to demonstrate the effectiveness and validity of the proposed methodology. The results reveal an optimal FM strategy for the building recommended using the novel algorithm, and its effectiveness is validated by FM experts. The proposed method will allow industry practitioners to quantitatively evaluate FM performance and make better decisions in selecting the optimal management strategy. Furthermore, the findings can advance the body of knowledge on building performance evaluation in view of quantitative metrics development.

Labeling and mapping existing infrastructure is one of the grand challenges for civil engineers in the 21st century. The challenge remains in finding an appropriate data collection method that rapidly collects structural and geometrical information of bridges and automatically converts it into three-dimensional (3D) models. Over the last decade, there has been a tremendous effort to develop prototypes for capturing the as-is condition of a bridge and converting it into 3D bridge-information models (BrIMs). Bridge-information models are 3D-information-rich data models that can be used in various phases of bridge design, construction, operations, and maintenance. As an alternative solution, researchers are now studying the processing of videos to capture the required 3D information (videogrammetry) and using algorithms to automatically extract 3D objects and convert the results into a BrIM. This study evaluates the applicability of a novel videogrammetric pipeline for automatically documenting the physical condition of bridges. It also describes the results of three case studies of highway bridge assessment and modeling in which 3D information is extracted from two-dimensional video frames and point cloud data (PCD) are generated. As the next step, the PCD can be converted into a data-rich BrIM object for further processing.

This paper presents a numerical investigation of the progressive collapse behavior of the precast RC frame subassemblages. An efficient numerical model for precast RC frame subassemblages under progressive collapse is developed based on an open-source finite-element software, in which the fiber beam element is used for the beams and columns and the Joint2D element is used for the beam-to-column connections. To consider the significant bond-slip effect inside the joint core of precast RC frame subassemblages, the stress-slip relationship for reinforcement bars with different embedded lengths is derived and used to generate the force-deformation relation for the springs incorporated in the Joint2D element. The numerical model is validated through comparisons with the experimental results of RC subassemblages subjected to column removal scenarios in terms of load-displacement curve, compressive arch action, catenary action capacity, and so on. Systematic parametric studies are conducted based on the validated numerical model to investigate the influence of some typical parameters of precast RC structures on the progressive collapse capacity of the subassemblages.

The horizontal-to-vertical spectral ratio is a widely used technique to identify fundamental frequency and amplification by both structural and geotechnical engineers. Following the 2015 Gorkha earthquake, ambient vibration measurement was conducted in central Kathmandu Valley considering representative building types. Well-designed high-rise reinforced concrete (RC), residential RC (poorly designed), brick masonry (cement mortar), medium-rise RC, and medium-rise precode RC buildings were chosen for ambient vibration measurement. As the first attempt to estimate the natural frequencies of buildings in Kathmandu Valley, ambient vibration records were taken at various heights of the buildings. Another aim of this study was to identify the possibility of vibration resonance in the existing building types; thus, free-field measurements were also taken during the building measurements.