Journal of Performance of Constructed Facilities

Forum papers are thought-provoking opinion pieces or essays founded in fact, sometimes containing speculation, on a civil engineering topic of general interest and relevance to the readership of the journal. The views expressed in this Forum article do not necessarily reflect the views of ASCE or the Editorial Board of the journal.

This paper presents different strengthening techniques to improve the shear capacity of existing thick concrete slab structures that were constructed without shear reinforcement. Reinforcing bars are installed into vertical drilled holes and anchored with epoxy adhesive to increase the shear capacity. Experiments on retrofitted beams, representing slab strips, showed that all of the strengthening techniques investigated resulted in increased shear capacities. The shear failure mechanisms of the strengthened beams showed that, as expected, current evaluation methods for elements with conventional, well-anchored stirrups can lead to an overestimation of the shear capacities. The efficiency of the strengthening techniques is strongly influenced by the performance of the end anchorage of the drilled-in bars. The effectiveness of the epoxy-bonded bars is a function of their embedded length and they can, in some cases, debond before they reach their yield strength. By using the maximum bar spacing required by the Canadian design code for bridges or the AASHTO-LRFD design specifications, bonded shear-reinforcing bars may debond and offer poor performance. A maximum transverse reinforcement spacing criterion is therefore suggested for the added bonded bars.

A case of damages in the secondary lining of a multiarch tunnel is studied by field investigation and numerical analysis, which is subject to asymmetry pressure and buried at shallow depth. The study focuses on the key influencing factors inducing these damages. The numerical analysis is implemented, taking account of the possible influencing factors obtained from field investigation, in which two cases with different numerical models are utilized to discriminate the effects caused by shallow tunnel depth and asymmetric pressure on the tunnel comparatively. The numerical result demonstrates that the topography with shallow depth and asymmetry pressure has much influence on the safety of the multiarch tunnel’s structure, and the cause of damages in the multiarch tunnel structure can be analyzed by field investigation and numerical simulation, which can provide the design basis for appropriate strengthening of the damaged tunnel structure.

This study investigated the response of reinforced concrete (RC) slabs in building structures to internal explosions. The performances of two slabs designed in accordance with the protective structural design and conventional gravity design approaches were evaluated in terms of midspan displacements, support rotations, and damage patterns. Data from available slab blast experiments in the open literature were used to validate the methodology. A numerical study was carried out for various high-explosive charges detonated underneath the RC slabs. Detonations were simulated using airblast-loading functions. The flexible boundary conditions for the slabs were provided by a one-story single-bay RC frame consisting of beams and columns. All of the reinforcements of the slabs, beams, and columns were modeled explicitly using line elements inserted into the volumetric finite-element mesh of the concrete material. Envelope values of the rebar rupture strain were also used in the parametric study. Results from the numerical study showed that rebar rupture strain was a key factor in the blast performances of both slabs. Current protective design approaches to RC slabs mainly consider support rotations. It is recommended that rebar rupture strain also be accounted for in protective design.

The main objective of this study is to investigate the seismic behavior of an optimized version of cable-sliding friction aseismic bearing system, which is a spherical bearing combined with a set of cables to control the sliding. Basic characteristics and design method of this bearing are introduced. An experimental study including axial tensile tests of the cables and pseudostatic tests of the bearing are conducted. Seismic features including hysteretic loops, friction coefficient, and lateral restraining stiffness are analyzed based on the test data. After the test, the bearing is dissembled and damages to the bearing are illustrated and analyzed. A numerical simulation method is carried out and comparisons with the experimental results are made. The numerical results compare favorably with the experimental results. Furthermore, a case study featuring an extra-dosed cable-stayed bridge is presented. The experimental data confirm the effectiveness of the proposed design yet indicate degradation in the lateral restraining stiffness of the bearing. The case study results imply that the proposed system can control the relative displacement between the girder and pier effectively and momentary increase in the time history of the girder acceleration and pier top acceleration could be witnessed accompanying the restraining behavior. This study may be of use for seismic optimization of bridges in seismic active region.

This paper aims to present an investigation about the effect of construction errors on the snow-induced failure of tribune columns and roof. The structure, located in the town of Kalkandere in the province of Rize, Turkey, collapsed on January 3, 2016 and is considered as a case study. This low-sloped built variable-truss steel roof structure supported on reinforced concrete columns of 3.2 m covers a total of $626.46{\mathrm{m}}^2$ closed areas in plan. The roof of the tribune collapsed partially without any indication during first snowfall after construction, at midnight on a winter day, fortunately before the opening hours. The meteorological records and observations of local people are combined together to estimate the intensity of snow load in the region and it is compared with the code specified values. The snow load value is derived as $3.14\mathrm{kN}/{\mathrm{m}}^2$, which is 4.19 times greater than the design value. A three-dimensional finite-element model of the existing steel tribune roof with reinforced concrete columns is generated for four cases considering project drawings and site investigations. The compressive strength of concrete is calculated as 13.50 MPa, the type of steel longitudinal and confinement bars is defined as S420. At the end of the study, it is shown that the reinforced concrete tribune structure with steel truss cantilever systems has enough stability, rigidity, and is located within the safety limits for Cases 1 and 3. The failures occurred during Cases 2 and 4. From the analyses, inadequate concrete strength was determined as a secondary parameter causing this failure. Also, it is indicated that the possible reasons for the collapse are some mistakes made in the design of connection details, incorrect arrangement of the structure, existence of short column, overlap regions between the rigid tribune blocks, and individual columns and construction workmanship errors.

Although bridge fires pose a real threat, the topic is not covered in current design codes. This paper analyses information related to 154 cases of bridge fires, proposes classifying the damage levels suffered by a bridge during a fire, and establishes the main factors involved in bridge fire damage, which include: type of vehicle involved in the fire and its position, vertical clearance of the bridge, and the type of material composing the deck. The analysis shows that wooden bridges are the most vulnerable and that a tanker carrying gasoline under the bridge, or that is on the bridge and causes a serious spill under the bridge, is responsible for most of the fires that result in the collapse or demolition of the bridge.

The cause and mechanism of a sinkhole that has occurred on the downstream shoulder of a large embankment dam are studied. Since the downstream shoulder of the embankment was softened as a result of saturation, the slope safety of the embankment dam was reanalyzed by extending the saturation zone beyond the filter layers. Calculation results show that the dam is not safe currently in the area of the sinkhole section. The source of this problem was sought. Excavation of a trench at the sinkhole section was planned to take immediate action against failure. This trench excavation resulted in a fast, inexpensive, unambiguous, and effective way to rapidly identify the reason for the sinkhole. Trench excavation showed that the sinkhole problem was associated with the deterioration of the curved trace of the bottom outlet conduit: a rupture in a steel conduit at a poorly welded joint and a poor concrete section with a lack of reinforcement. High reservoir pressure through the rupture caused particle rearrangements, heave occurrence, upward propagation of cavities, and finally a sinkhole. In the study, remedial measures and the lessons learned from the case are also explained.

The 2011 Van earthquakes revealed that although earthquake-resistant codes were revised after significant research and after each major earthquake, construction quality had a little progress in the region. A total of 63 RC residential buildings that collapsed or were severely damaged in 2011 Van earthquakes were investigated in detail. It was found that there is an increasing trend in terms of number of stories in Erciş, Turkey. However, not only the taller buildings experienced more damage but also the shorter ones were damaged or collapsed. Column ratio has a decreasing trend but shear wall ratio increases with time. As for the ratio of the total vertical elements to the total floor area, it has a slight decrease with time. Although some design projects provide lower reinforcements, after 1995, the reinforcement ratio was either close to 1% or greater. Reinforcement ratio at the site was found to be lower than the ones specified in the design projects. Most of the buildings had shear walls but they were mostly oriented in the weak axis of the building and the as-built shear capacity of the buildings was found to be 50–60% of their design shear capacity. Concrete compressive strength was approximately 8 MPa. Some buildings were vulnerable even under gravity loading.

Cold in-place recycling (CIR) is a type of rehabilitation strategy that has shown to significantly improve the condition of flexible pavements with adequate subgrade support. The process involves milling the distressed existing surface layer(s), adding asphalt binder (e.g., emulsion, foamed) and then recompacting the modified mixture. Over time, there has been a steady increase in CIR rehabilitation projects in Iowa. Although pavement restoration is the primary goal, it is equally important to investigate factors that influence CIR performance to determine the effectiveness of the rehabilitation method on the pavement structure. This study evaluated the performance of approximately 100 CIR sections in the State of Iowa. The pavement sections included in the study showed that CIR rehabilitation significantly reduced pavement distresses. The analysis found that CIR mitigates pavement distresses such as transverse cracking, longitudinal cracking, and fatigue cracking while improving the roughness or the international roughness index (IRI). The IRI, a measurement of serviceability and performance, showed that thicker CIR layers remained smoother longer. The overall findings of this study can be used as guidance for making future decisions for pavement rehabilitation and understanding the interplay between CIR thickness and IRI.

This paper presents experimental and numerical studies of reinforced concrete flat-plate structures. Experiments were performed on six interior slab-column connections without structural integrity reinforcement to examine their punching and postpunching behaviors. The test variables included slab tensile reinforcement ratio and lateral restraint at the slab boundary. The experiments indicated that, under the level of restraint achieved in the tests, the compressive membrane action could enhance the punching resistance by as much as 9.5%. The tests also showed the slab-column connections without continuous compressive bars at the columns had a postpunching loading capacity of about 50% of the failure load, but this residual capacity cannot be maintained under large deformations. It was found that anchoring the slab tensile reinforcement into slab by hooks provided an alternative approach to achieve stable postpunching capacity. The numerical simulations confirmed the effectiveness of a macromodel for flat plates. The analyses also indicated the effects of compressive membrane action on punching resistance is a function of slab in-plane restraint and can significantly increase the resistance of a flat-plate building to progressive collapse.

Interferometric radar is popular equipment able to perform remote dynamic testing of large structures (towers, bridges, and buildings) by detecting the displacement in time in the line of sight between the radar and geometric discontinuities in the engineering structures under test. The case study of San Gimignano village in Italy has been one of the largest measurement campaigns using this kind of equipment. The masonry towers of the ancient village have been measured, and the primary lesson learned was about the limitations of this technique when used in field. Vegetation, scaffoldings, lightning rods, and narrow streets are all possible hinderances that can prevent a correct measurement of the displacement in time.

Machinery infrastructure is usually prone to stoppage due to unexpected breakdowns. This paper analyzes possible failures root causes of manufacturing facilities, including machinery, to improve their performance. The research methodology utilizes a fact-driven statistical approach to investigate the statistical relationships between different affecting factors. These include failure modes, durations of downtime, working shifts, and products. Experimental designs models were employed in this paper, based on the analysis of variance (ANOVA) test and the Kruskal-Wallis test in combination with Tukey’s method for pairwise comparisons. ANOVA analysis identifies different downtime durations influenced by different types of failures. Similarly, the Kruskal-Wallis test results show that downtime durations are affected by different types of failures and not affected by different products and production lines. A case study was done on a dairy plant in Saudi Arabia where ten types of failures were identified. The results showed the top ranked failures to be finished product clearance, setup delay, raw material rejection, mechanical failure, and electrical failure. The findings help the management to develop learned lessons that help to minimize the cost and consequences of having frequent failures.

Buildings are being constructed at an alarming speed as a result of unlimited demands around the world. However, lack of initiatives from building owners in undertaking systematic and planned preventive maintenance for privately owned residential buildings has become a contributing factor to premature aging and dilapidation. Most building owners rely on building professionals to take up the responsibilities of maintenance works. Building maintenance becomes a major concern of most building professionals in Hong Kong. However, maintenance budgets do not always meet the ever-increasing needs. Priorities must be set for different aspects of maintenance works. Priority setting is normally based on the professional knowledge and experience of building professions such as property managers or building surveyors, whose attitude may affect the priority setting and the decision making. Maintenance priority setting refers to establishing priority for different maintenance aspects. This paper investigates the attitude toward maintenance priority setting from building owners and building professionals by examining (1) the opinions on professional knowledge and experience that affect maintenance decision making; (2) the overall standards of private residential buildings; (3) the responsibilities for proper upkeep of the buildings; and (4) reasons for building deteriorations. A questionnaire survey among building owners and building professionals was conducted. The building owners and building professionals generally agreed that buildings are of poor quality, although the building owners do not believe that the proper upkeep of the buildings is their responsibility. The owners’ lack of awareness, lack of voluntary initiatives, and unwillingness to bear the maintenance cost are the three most common reasons for building deteriorations found from the survey results. The paper suggests improving awareness of building maintenance by providing seminars to owners and the public, and increasing the maintenance budget for residential buildings.

New sources of energy are necessary today to totally avoid oil dependence. People are researching renewable energy systems (RES) because RES are a challenge for economies and clean energy sources around the world. This paper presents an overview of the current status of energy production based on RES technologies in Mexico. Typical yield failure envelopes obtained with RS3 software in three-dimensions (3D) are included. These envelopes have the special soil characteristics found in marine sediments. Modeled anchors correspond to suction caissons and two typical geometries were studied. Additionally, a study of the seismic response of an offshore site was made using the computer program EERA, since earthquakes are events that frequently affect the infrastructure, making the design always dependent on transient events. A response spectrum is presented. The time histories of acceleration used to obtain the spectrum correspond to earthquakes localized in the area of the Gulf of Mexico.

During the shield tunnel construction period, influence of ground displacement and deformation of soil around the tunnel in different grouting pressure must be researched to ensure safety of the tunnel and buildings adjacent to the project. In this paper, some typical sections of the Changsha No. 1 subway is taken as an example. Deformation of soil and displacement of ground are calculated in different geology conditions and grouting pressures. At the same time, the calculation result is contrasted with monitoring data of the real project, and some useful conclusions are drawn that are important to determine the construction parameters reasonably and control the ground displacement effectively. The main conclusions are as follows: (1) while the grouting pressure increases, deformation of surrounding rock and ground displacement decreased obviously, so different grouting pressures should be designed at different parts of the tunnel during excavation period to balance the deformation of the tunnel; (2) displacement curves of the ground perpendicular to the tunnel axis met the character of normal distribution curve, so as grouting pressure increased, values of the ground displacement decreased; (3) the numerical method of the paper was proved to be useful in simulating shield excavation of tunnel, and the Peck method was suitable to forecast ground displacement of tunnel excavation in silty clay layer; and (4) secondary grouting can be used during the construction period to control ground displacement.

This paper presents a support system for the inspection, diagnosis, and rehabilitation of door and window frames with the purpose of standardizing and systemizing the procedures of those responsible for these actions. In this study, a classification of anomalies is proposed along with their probable causes. To assist the diagnosis of the anomalies and respective causes, a classification of in situ nondestructive tests and repair techniques is presented to ensure the maintenance and/or to restore the functional properties of the framework system. Within the study several correlation matrices were created relating anomalies with other anomalies, probable causes, and diagnosis and rehabilitation techniques. This system was validated and calibrated through an extensive campaign of 295 frame inspections in 96 Portuguese army and air force buildings. The implementation of this system supports the inspection activities of a proactive maintenance strategy and the standardization of inspections, resulting in an increase in the effectiveness and objectivity of the actions to be taken upon the occurrence of these anomalies.

In recent years, many bridge collapse accidents have been attributed to the passage of extra heavy trucks (EHTs, gross weight $\ge 80\mathrm{t}$) in numerous countries. Compared with the standard traffic loads in design specifications, the actual characteristics of EHTs are very difficult to predict because they may be specific to the management, charge policy, or other properties of the route. In a previous publication, the authors researched the characteristics and dynamic impact of EHTs on Chinese expressways. In the current study, long-term traffic monitoring data were statistically analyzed to identify the key characteristics of EHTs on Chinese first-class highways. Based on the EHT scenarios extracted from the weigh-in-motion (WIM) data, which can be used to record the traffic information of moving vehicles, a comprehensive simulation analysis was conducted by an in-house advanced dynamic bridge–traffic interaction model on five typical simply supported T-beam bridges. The bridge response and dynamic impact factors (DIFs) of EHTs were numerically investigated, and reasonable expressions for calculating the DIFs were proposed. Finally, the load effect calibration under EHTs was performed when the road surface condition was average. These findings can be used as additional references for bridge codes and safety assessment by practicing engineers.

An engineering failure with serious cracks and heaving in the roadway subbase because of the overuse of phosphogypsum was investigated, and an effective stabilization solution was implemented. For this purpose, mix-proportion design, compaction, expansion, and shrinkage tests were performed on the treated mixture to investigate the engineering properties. Based on the laboratory results, in situ tests were conducted to verify the engineering behaviors of the recycled subbase, which included the static plate load test (SPLT), dynamic cone penetrometer test (DCP), Benkleman beam method test (BBM), and portable falling-weight deflectometer test (PFWD). The test results show that the swelling problem can be controlled by adding lime and fly ash to the problematic mixture at a reasonable proportion. The in situ tests show that the average resilience modulus of the SPLT was 191.5 MPa, which is approximately four times the value before the treatment. The dynamic modulus of the DCP test and PFWD test also indicate an increase of approximately $4–5\text{times}$, and the deflection value of the BBM test was only 37.2 mm after the treatment. The in situ test results show that the recycled subbase can satisfy the roadway requirements and present a good performance. The proposed mix proportion of $6.5\%\mathrm{L}+20\%\mathrm{F}+73.5\%\mathrm{H}$ was applied in this problematic subbase. The construction control requirements are outlined in this paper. The treated roadway subbase has worked well for nearly 9 years, which indicates a successful application of in situ stabilization.

Piles could be damaged under major lateral loading environment for a long period. The sources of lateral loads are lateral earth pressure, wind loads, seismic loads, impact loads from ships (berthing and mooring) eccentric loads on columns, river current and mud movement loads in alluvial settings (foundations subject to scour), ocean wave forces, slope movements, and cable forces on transmission towers. Hence, it is important to improve the lateral load capacity of pile foundation. In recent years, fiber-reinforced polymer (FRP) jacketing has become popular to retrofit existing deficient piles. The light weight, high strength, and corrosion resistance of FRPs made them particularly suitable for repair. This paper presents the experimental study on glass and carbon fiber-reinforced polymers (GFRP and CFRP) strengthened reinforced concrete (RC) piles subjected to static lateral loads. The effects of GFRP and CFRP strengthening on RC piles were investigated.

Pile foundations are usually used when heavy superstructural loads have to be transmitted through weaker subsoil. Piles are also subjected to significant amounts of lateral loads and overturning moments besides axial loads. Lateral loads are in the order of 10–15% of the vertical loads in the case of onshore structures, whereas in the case of coastal and offshore structures, these lateral loads can exceed 30% of the vertical loads. Therefore, proper attention has to be given in designing such pile structures under lateral loads. In recent years, many investigations have addressed the externally bonded fiber-reinforced polymer composites for strengthening of concrete structures. This paper presents an experimental study on glass and carbon fiber-reinforced polymers (GFRP and CFRP) strengthened reinforced concrete (RC) piles subjected to cyclic lateral loads. The effects of GFRP and CFRP strengthening on RC piles were studied. The load deflection, stiffness degradation, and energy dissipation of piles are also presented.

The load-carrying capacity of reinforced concrete bridges can degrade over their service life through the initiation of deterioration mechanisms induced by fatigue, corrosion, cracks, and spalling. Analyses of residual capacity and time-dependent reliability of such bridges are significantly important information in the decision-making process of identifying the nature and timing of rehabilitation. It is noted in the literature that deterioration mechanisms such as chloride ingress, sulfate attack, and alkali-silica reaction have variable rates of deterioration governed by a large number of uncertain parameters. In such instances, a probabilistic approach provides a rational basis for estimating the uncertainties of residual capacity and reliability. In this paper, the authors present a probabilistic method to evaluate the time-dependent reliability and failure of concrete bridge elements. The probabilistic distribution of surface chloride concentration, diffusion coefficient, critical chloride concentration, and material variables were identified from literature. Monte Carlo simulation was employed for modeling the increases of live loads and the degradation of the component to obtain the time-dependent reliability curves for design service life. The methodology is further demonstrated by a pier column as an illustrative example. Results showed the reduction in resistance and the risk of failure periods. Further parametric studies showed that concrete cover depth and water-cement ratio have significant influence on the time-dependent probability of failure and reliability index. Overall, it has been shown that the methodology is generic and valuable information on residual capacity and time-dependent probability of failure can be applied to performance assessment and lifecycle for both new and existing structures.

The present study was undertaken to understand the moisture damage resistance of unmodified and ground tire rubber (GTR)–modified asphalt binders containing three different type of warm mix asphalt (WMA) additives using the surface free energy (SFE) approach. The SFE parameters of unmodified and GTR-modified asphalt binders with and without WMA additives were determined in the laboratory using the Wilhelmy plate method. The SFE of two types of aggregate, namely, granite and limestone, were adopted from literature. Thereafter, work of adhesion, work of cohesion, work of debonding, and energy ratio (ER) were estimated for a total of 16 different combinations of aggregate and asphalt binder. An attempt was made to evaluate sensitivity of SFE parameters with elemental composition (carbon, hydrogen, nitrogen, and sulfur) of asphalt binder. The results showed that moisture damage resistance of unmodified and GTR-modified asphalt binder decreases with addition of WMA additives. The control asphalt binder with Rediset (Akzo Nobel, Netherlands) showed better bond with aggregate, followed by Sasobit (SasolWax, Hamburg, Germany) and Advera (PQ Corporation, Malvern, Pennsylvania). The limestone aggregate showed better moisture damage resistance compared with granite aggregate. The elemental composition (CHNS) of an asphalt binder found to have a fair correlation with SFE parameters.

Four case histories are presented to define lessons that can be learned from the investigation of the failure of slabs, footings, and deep foundation elements caused by heaving of expansive soil. For each case history the site conditions, the nature of the distress, and the scope of the forensic investigation are presented. Several factors that contribute to the cause of the failures are identified, and commonality between the various factors is noted. The most commonly identified factors relate to inadequate soil sampling, soil testing, and analysis of the data, resulting in deficient design and poor construction practices. Another contributing factor relating to failure is inadequate drainage. The general conclusions to be drawn are that it is important to apply rigorous engineering practices on expansive soil sites. The engineers and contractors must understand the nature of expansive soil and have an appreciation for the types of problems it can cause.

Stiffened slabs-on-grade are one of the most efficient and inexpensive foundation solutions for lightweight structures on shrink-swell soils. The Ellison Office Building (EOB) is a 1-story steel-framed building founded on a clay formation of high shrink-swell potential. The foundation system of the EOB is composed of a rectangular stiffened slab-on-grade with approximate dimensions of 18.3 by 38.1 m. The slab thickness is 0.1 m, and the depth of all stiffening beams is 1.05 m. Beam spacing distances, center to center, are 3.05 and 3.81 m in the short and long directions, respectively. Exploration of subsurface soil conditions at the EOB site took place to determine soil index properties as well as unsaturated moisture diffusion and volume change characteristics for unsaturated soils. Monitoring the movements of both the slab-on-grade and the 4.5 m soil underneath continued for 2 years after foundation construction, since September 2004. Investigating the EOB foundation performance in light of the soil-structure interaction characteristics of the foundation showed two main distinct slab movement patterns: continuous global heave and localized fluctuating slab edge heave and drop movements.

In this paper, the Barcelona basic model (BBM) was implemented in a finite difference-based computer program to simulate the behavior of unsaturated soils subjected to wetting. The BBM implementation was verified using analytical solutions, and the verified model was used to simulate the wetting-induced response of a compacted fill embankment subjected to complete saturation as the worst-case scenario for design. Results showed that considerable amount of total and differential settlements could develop at the top surface of the embankment. Additionally, upper sections of the embankment had a tendency to heave, whereas lower sections under larger confining stresses could collapse due to wetting. Results of a subsequent parametric study indicated that initial moisture content, embankment height, and slope angle have significant influences on the wetting-induced deformations and stability of unsaturated embankments.

Energy pile, piled foundation incorporating pipe loops for ground source heat pump systems, has been implemented in more and more countries. However, the mechanical performance of energy pile has not been comprehensively studied. To improve the understanding on the performance of energy pile, a field study on energy pile is carried out in this study. A prestressed concrete pipe pile installed with water pipe loops inside was tested as an energy pile in the field. The performance of energy pile during heating and cooling was investigated by using vibrating-wire stress gauges and temperature sensors. The field tests reveal that the temperature influence distance of the energy pile on surrounding soil is approximately 0.5 m from the center of the pile after heating for 60 h. The axial force of energy pile increases/decreases with the increase/decrease of temperature at different rates at different depths. The neutral plane shifts from above 7.7 to below 7.7-m depth because of heating. The magnitudes of shaft resistance increase with temperature increase and decrease with temperature decrease.