Journal of Performance of Constructed Facilities

The deterioration attributable to corrosion of concrete structures reinforced with unbonded, posttensioned tendons is a costly problem. Recent research has shown composite materials such as fiber-reinforced polymers (FRP) to be suitable alternatives to steel because they provide similar strength without susceptibility to electrochemical corrosion. Carbon-FRP (CFRP) in particular has great promise for prestressed applications because it shows resistance to corrosion in environments that might be encountered in concrete and experiences less relaxation than steel. This paper outlines the testing and implementation of a posttensioned system that uses CFRP tendons to replace corroded, unbonded posttensioned steel tendons. This system was then implemented in a parking garage in downtown Toronto. To the writers’ knowledge, this is the first example of an unbonded, posttensioned tendon replacement using FRP tendons. The system used split-wedge anchors designed specifically for CFRP tendons. The dead end was anchored by directly bonding the tendon to the concrete slab. The CFRP tendon was successfully inserted in the opening created by the removal of the corroded tendon and stressed. Although the system was shown to be feasible, the current anchorage configuration results in load losses of up to 60% during the transfer. Changing the orientation of the anchor was found to reduce the load loss to an acceptable range of 1–9%.

Recently, Turkey has been hit by several moderate to large earthquakes that resulted in significant loss of life and property. The 1998 Adana and 1999 Marmara earthquakes caused severe damage not only in residential buildings but also in industrial buildings. Most of the industrial buildings in Turkey are constructed as prefabricated structures. Prefabricated structures are preferred because of their economic and rapid production. In the present study, the earthquake behavior and infill wall effects for single story hinged industrial prefabricated buildings were investigated. Nonlinear pushover, performance-based, time history, and fragility analyses were carried out for a sample prefabricated industrial building. Infill wall effect was investigated by adopting a diagonal strut model. The structural behavior and load-deformation relationship of prefabricated industrial buildings both with and without infilled walls were evaluated and compared. Results of the study show that masonry infill walls can affect the lateral load-carrying capacity and modify the earthquake response of prefabricated industrial buildings.

This paper proposes an expert system to support the inspection and diagnosis of partition walls or wall coverings mounted using the drywall (DW) construction method. This tool allows the succinct characterization of the pathological situation of each DW inspected. It also eases the systematization of the inspections included in periodic maintenance actions, thereby preventing future defects. The proposed tool includes a classification of defects in DW and their probable causes. The correlation matrices between defects and between defects and probable causes complement these classifications. Finally, the diagnosis methods and the repair techniques suitable for each DW defect are classified. All the defects, diagnosis methods, and repair techniques have individual files containing their significant information. The proposed classifications were validated via standard inspections of DW in three shopping centers, four stores, a school, three offices, a gymnasium, two condominiums, a hospital, four hotels, and two restaurants.

Seasonal variation of ambient temperature is rarely a cause of concern in structural design of normal buildings, but it has been found to cause recurring distress in a pyramid-shaped reinforced concrete (RC) building located in the foothills of the Himalayas. Abnormal stresses developed because of thermal movement of a large inclined roof exposed to direct sun and anchored to short columns at corners. Integral connection of a long corridor with the building compounds the effect of thermal movement of the building and corridor in opposite directions. A conventional linear analysis cannot correctly predict the observed distress. However, nonlinear analysis predicts the distress in close agreement with the observations. The building is situated in an area of high seismicity, and the inclined roof has a peculiar effect on the seismic response of the building, resulting in soft story phenomenon. Alternative retrofit schemes to safeguard the building against thermal and seismic actions are evaluated. It is observed that some of the retrofit strategies that are suitable for temperature effects may not be suitable for earthquake action.

This paper studies the cross-sectional behavior of steel columns strengthened with fiber-reinforced polymers (FRPs). The composite column is constructed by wrapping the steel I-section column with epoxy-saturated glass- and carbon-FRPs (GFRP and CFRP) sheets in the transverse direction and subsequently filling the voids between the FRP and the steel with concrete. Experimental tests were performed on stub columns under axial compression including one to three CFRP wraps. A corner treatment technique, to avoid stress concentration at the corners and to improve confinement efficiency, was also investigated. A simplified analytical model was developed to predict the axial behavior of the composite columns. Experimental results showed significant enhancement in the behavior of the composite columns primarily attributable to the confinement mechanism imposed by the FRP jacket and concrete. Increasing the corner radius resulted in higher compressive strength of the confined concrete and ultimate axial strain of the composite columns. Good agreement between the analytically developed axial load-displacement relationships and the test data indicates that the model can closely simulate the cross-sectional behavior of the composite columns.

Increasing appraisal of the durability, conservation state, and changeable use and function of old buildings in urban centers relies a great deal on the structural safety evaluation of vertical load capacity and the ability to resist horizontal forces. The need to assess seismic vulnerability, particularly of traditional masonry buildings, is a key issue. Evaluation of the seismic vulnerability of old buildings is essential in the definition of strengthening needs and minimization of damage from seismic actions in the safeguarding of built heritage. A three-dimensional model was developed for an aggregate of four traditional masonry buildings located in the old city center of Coimbra, in Portugal. The finite element modeling of these buildings has aimed to identify structural fragility, understand the damages detected, and evaluate the global structural safety of these types of buildings. The primary results obtained in this case study helped to interpret the structural damage and stress distribution, and verified global stability and its consequences. Different strengthening techniques to improve the global behavior of these buildings were modeled and analyzed. A comparison of the efficiencies of strengthening strategies is also discussed.

Technical due diligence (TDD) as an evaluation of the performance of constructed facilities has become an important new field of practice for consultants. Before the financial crisis started in autumn 2008, TDD represented the fastest growing activity in some consulting companies. TDD is usually carried out for buyers or sellers involved in real estate transactions. It can also be part of mergers, including real estate and other assets, or part of facilities management outsourcing. This paper is based on a case study and an interview survey of companies involved in TDD consulting in Denmark and Italy during 2009. The research identifies the current practice and compares it with the recommended practice in international guidelines. The current practice is very diverse and could, in many cases, be improved by a more structured approach and stricter adherence to international guidelines. However, the investigation of the current practice also identifies examples of value-adding practices, which can give the companies in question competitive advantages by differentiation and/or give input to improvements of the recommended practice guidelines.

Adjacent precast, prestressed multibeam bridges have often been used for medium- and short-span bridges. However, there have been longitudinal cracking problems in shear keys and overlays commonly seen on some adjacent precast multibeam bridges during their service years. The fundamental reason for the problem is the poor transverse connection. Transverse posttensioning is important to the transverse connection design, although the posttensioning varies largely from state to state. Especially for adjacent precast solid multibeam bridges without diaphragms, there are no theoretical justifications for designing the transverse posttensioning. In this study, an approach based on the concept of shear friction, which is used for designing the transverse posttensioning in adjacent precast solid multibeam bridges, is presented. Furthermore, a newly rehabilitated bridge was load tested with the primary purpose of evaluating the effect of transverse posttensioning under truck load. Also, the calibration of a numerical model was conducted. At last, suggestions about design and construction of shear keys, with reference to the experience in other states, are presented for the practice in the state of Maryland.

Transmission line towers, though designed per code provisions, may fail during mandatory testing required in many countries. Different types of premature failures that were observed during full-scale testing of transmission line towers at Tower Testing and Research Station, Structural Engineering Research Centre, Chennai (CSIR-SERC) are studied, and the results are discussed in detail. The failures are modeled using finite-element software, and the analytical results and the test results are compared with various code provisions. The nonlinear finite-element analysis program NE-Nastran was used to model the elastoplastic behavior of towers. Bracing members with slenderness ratios above 170 become ineffective, even though they have to carry insignificant forces. Importance of design assumptions and connection detailing in overall performance of towers were studied. Nonlinear finite-element analysis is useful in understanding the system behavior and for prediction of the failure pattern and ultimate load. Based on the test results, the importance of studying these failures is highlighted and significant conclusions were drawn.

The dynamic compaction (DC) method is a versatile ground treatment technique with growing popularity. It is applicable to a wide variety of soil types and conditions, particularly sandy materials and granular fills. This study presents a case history of the dynamic compaction with a high energy level of $6,000\mathrm{kN}·\mathrm{m}$ on granular deposits at a site in China. The reclaimed site featured loose backfill with heterogeneity and saturated silt. In order to properly deal with such soil conditions and to optimize the DC design, field tests were conducted to determine the influencing factors in DC. Deformation tests were performed to ascertain the rational spacing of impacts and the optimal number of drops and to provide proofs to the adjustment of the original DC procedure. Monitoring of the pore water pressure helped obtain the time delay between passes. The approach to assess the depth of improvement was discussed based on interpretations of the spectral analysis of surface waves (SASW) test. Analysis of the SASW and plate-load tests demonstrated significant improvement in the soils at the site, with no obvious weak layers. Following dynamic compaction, the allowable ground-bearing capacity and the depth of improvement at the site were no less than 270 kPa and 7.4 m, respectively.

The pavement network represents a visible and expensive component of a highway agency’s total transportation investment and, thus, requires proper management. Historically, the agencies managing these investments have relied on manual distress surveys carried out by personnel who drive the network and provide subjective condition assessments. Surveys completed by a highly instrumented vehicle driven at standard travel speeds have become a viable alternative. Questions regarding accuracy and consistency with existing survey protocols still remain with these automated survey methods. This paper reports on the findings from a study to evaluate automated distress surveys. Vendors and manual survey teams have evaluated the distresses along a test loop in North Carolina using two survey protocols: (1) an agency’s standard network level survey, and (2) the long-term pavement performance survey. Communication between the vendor and agency is the single most important factor that allows for the proper utilization of automated surveys for network-level surveys. For best results, agencies considering using automated methods may wish to utilize an initial test loop to calibrate the automated distress results.

The use of water main break history as a proxy for condition has become common practice because of the high costs associated with direct assessments. Statistical deterioration models predict future water main breaks on the basis of historical patterns. Many municipalities are beginning to understand the value of utilizing water pipe break histories to manage their noncritical distribution networks via deterioration models. This paper presents a generic IDEF0 process model for developing water main deterioration models. Two common statistical deterioration models for water pipes are compared: rate-of-failure models (ROF) and transition-state (TS) models. ROF models extrapolate the breakage rate for a particular cohort of pipes and do not differentiate between the times between successive failures. On the other hand, transition-state models attempt to model the time between successive failures for pipes. This paper presents a comparison and analysis of ROF models and transition-state models by using a single data set for cast- and ductile-iron pipes in the City of Hamilton, Ontario, Canada. The paper compares the models’ ability to support breakage forecasting, long-term strategic planning, and short-term tactical planning. Best practices for pipe segmentation in support of water main deterioration models are presented.