Journal of Performance of Constructed Facilities

It is more rational to analyze permanent geosynthetic reinforced soil (GRS) walls against seismic loading based on their behavior during service life, but it has seldom been attempted. Calibrated finite-element procedure was used to investigate the reinforcement loads of GRS walls subject to seismic loading during service life, the results of which were compared to those predicted by Federal Highway Administration (FHwA) guideline. Parametric studies were carried out to investigate the effects of various wall parameters and characteristics of earthquake excitations. It is found that due to the isotach behavior of geosynthetics, the reinforcement loads during earthquake that occurs 10 years after construction were similar to those if the earthquake occurs at the end of construction. The FHwA method predicted roughly the maximum reinforcement load but it could not consider strain softening of soil and characteristics of earthquakes. The horizontal locations of maximum reinforcement load in lower reinforcement layers were farther away from the facing units than Rankine’s surface, which is believed to come from the potential compound failure.

Geophysical surveys could contribute significantly to remediation programs for damaged buried engineering structures. Resistivity profiling and mapping techniques used in this work allow rapid and one of the most cost-effective ways of characterization and visualization of internal defects of drainage and watering systems of football playgrounds in a nondestructive way. Cost-effective and nondestructive testing can be valuable assets for diagnosis, realization, and restoration of football playgrounds.

An investigation was conducted to determine the root cause of the premature pavement failure. The premature pavement failure occurred in the form of rutting and alligator cracking. Although the affected portion was repaired by removing and replacing the top 75-mm asphalt concrete (AC), the repaired AC experienced recurring rutting and alligator cracking in a few weeks. Through extensive field and lab testing, it was found that the weak base is the root cause of the premature failure and the brittleness of the AC is secondary. However, both the base and AC were built according to plan and met the current material and field density requirements. It was concluded that density alone for construction quality control is not sufficient, as it was not able to protect against premature failures from occurring. Although there are many different ways to minimize premature failures, an immediate action is to include proof rolling in construction quality control. Proof rolling has been used with success to ensure proper compaction and to locate unstable areas, as the stability is greatly influenced by the degree of densification achieved during compaction.

The Hellenic electrical distribution lines have been basically supported with the use of wood poles. Outages due to aging, degradation, or broken wood poles may infer significant costs due to repair and loss of energy to consumers. Lifetime estimation of wood poles is significant for maintenance and replacement decisions at the power utility. The paper presents a methodology, based on a statistical analysis, for the evaluation of the life expectancy and the production of a survival curve of a typical Hellenic distribution wood pole in-service. The proposed methodology intends to minimize the life-cycle cost of inspection and refurbishment of wood poles in the distribution network of Hellas, something that is really important in the new competitive and liberating Hellenic electrical energy market.

Metro systems usually offer an attractive alternative for mass transit transportation system in most large cities. Such infrastructures require proper maintenance and rehabilitation (M&R) programs to maintain them within an acceptable level of operational and safety performance. The Markov decision process (MDP) has been widely used to find the optimal M&R decision policy for situations that deal with uncertainties. A drawback of the traditional MDP approach is that it uses discrete number of states in the analysis as well as a stationary transition probability matrix (TPM). Also the MDP is based on the Markovian or “memory-less” property, which is not necessarily the fact for all aging infrastructures. This research presents a case study on a deteriorating slab in a Montreal metro. The traditional MDP is employed with linear programming to determine the optimal rehabilitation profile. Three different methods are employed for calculating life-cycle cost: (1) the average expected discount cost per time period that is normally used with the traditional MDP; (2) continuous rating approach; and (3) dynamic or time-dependent TPM. Results revealed that the continuous rating approach provides lower values compared to the traditional approach. Dynamic TPM reflects better the infrastructure behavior but necessitate additional data gathering. This research mainly benefits metro management agencies and enhances the MDP practice by overcoming some downsides of the traditional methodology.

In this study the vertical push-down analysis was conducted to investigate the resistance of steel moment frames for progressive collapse. The analysis was carried out by gradually increasing the vertical displacement in the location of the removed column and the vertical load in all spans corresponding to the increase of vertical displacement. The analysis results showed that the load resisting capacity increased as the number of stories and the number of spans increased. However, as the length of a span increased, the load resisting capacity against progressive collapse decreased. The load-displacement relationships obtained from push-down analyses were compared with those obtained by incremental nonlinear dynamic analyses, and the results showed that the maximum load factors resulted from the dynamic analyses were a little less than those from the push-down analyses. This implies that the push-down analysis might overestimate the inherent capacity of structures against progressive collapse.

The goal of this study was to develop an understanding of the nature of wave loading on a wood-framed scale residential building model for a variety of building configurations and test conditions. Testing was performed on a 1/6th scale two-story wood-framed residential structure. The structure was impacted with waves and tested in both flooded and nonflooded conditions. The measured forces were mainly uplift forces due to wave loading, and resulting overturning moments. The qualitative analysis of the data showed that differences in structural stiffness throughout the structure will cause a different load distribution in the structure, e.g., overhanging eaves above the garage can provide unanticipated loading conditions, water traveling beneath the structure generates predominantly uplift forces, and the effect of waves breaking on or near the structure greatly increases the loading. The ratio of force from the windows closed condition to the windows open condition is approximately 2.5:1.

The study of earthquake engineering has made significant strides over the last one-half century with scientists developing methods to better understand the basis and mechanisms of earthquakes and engineers working to mitigate economic loss and fatalities. A paradigm known as performance-based seismic design (PBSD) not only provides life safety to building occupants, but seeks to control structural and nonstructural damage in buildings and other structures. The development of fragility curves based on the well-known Park-Ang damage index is examined herein. This type of formulation can provide the information needed to assess the seismic vulnerability of a structure. Existing shake table test data from the NEESWood Project’s test of a $223{\text{m}}^2$ (1,800 sq ft) two-story house was combined with a participant survey to calibrate a damage model. The result was the development of damage fragilities based exclusively on nonlinear time history analysis. Then, the proposed numerical damage model was applied and fragility curves were developed for a six-story light-frame wood condominium building. The results appear logical based on observations of system-level shake table tests over the last decade, and thus the method shows promise provided significant torsion is not present in the system.

In this study, a nonlinear model is developed to study the response of blast-loaded reinforced concrete (RC) columns. The strain rate dependency and the axial load and $P-\Delta$ effects on the flexural rigidity variation along the column heights were implemented in the model. Strain rate and axial load effects on a typical RC column cross section were investigated by developing strain-rate-dependent moment-curvature relationships and force-moment interaction diagrams. Analysis results showed that the column cross section strength and deformation capacity are highly dependent on the level of strain rates. Pressure-impulse diagrams were developed for two different column heights with two different end connection details (ductile and nonductile) and the effects of the axial load on the column midheight deflection and end rotation at failure were evaluated for both connection types. Based on the results of this study, a pressure-impulse band (PIB) technique is proposed. The PIB technique presents a useful tool that covers practical uncertainties associated with RC column reinforcement details as well as possible increase of column axial loads resulting from different blast-induced progressive collapse scenarios. Finally, the uses of the PIB technique for vulnerability screening of critical infrastructure or postblast capacity assessment of RC columns of target structures are presented.

This study presents investigations regarding visual inspection, dynamic testing, and finite-element modeling of an approximately 80-year old reinforced concrete tied-arch railway bridge that is still in service in Turkey. Investigations were conducted as part of a systematic periodic inspection along Ankara-Zonguldak railway line. The bridge is subject to heavy freight trains with increasing axle loads. Field tests such as material tests and dynamic tests were used to calibrate the finite-element model of the bridge. Detailed information regarding testing and model updating procedure is given. Based on test results, computer model was refined. The calibrated model of the bridge structure was then used for structural assessment and evaluation. Despite sufficient overall safety, local details were found to be problematic. Due to insufficient bond length in hanger-to-arch connection, a strengthening scheme using steel channel sections was proposed.

On September 11, 2006, “unusual” deflections of an overhead bridge-mounted sign support truss along IR 75 in Dayton, Ohio were reported. Investigation by Ohio DOT road crews revealed the complete fracture of two truss members near one of the truss supports. While total collapse did not occur, such an event could have catastrophic consequences along a major arterial roadway like IR 75. This concern, along with the fact that a similar failure occurred near Cleveland, Ohio in 2004, prompted an investigation that is the subject of this manuscript. Results of the investigation are based upon a combination of in situ field monitoring of traffic-induced bridge vibrations at the location of the failed sign support truss, finite-element simulation of the expected dynamic response of the original truss in such an environment, the length of service of the truss at the time of its failure, the volume of truck traffic on the bridge in question during that time of service, and metallurgical examination of the failed components of the sign truss. The conclusion of the investigation is that extremely high-cycle fatigue of the chord-web diagonal welded connection was the cause of the truss failure. The in-service effective stress range of the AASHTO Category ET connection in question was most likely below the currently specified AASHTO constant amplitude fatigue limit for the detail, but the enormous quantity of response cycles (approaching or even exceeding 1 billion cycles) such a bridge-mounted sign on a heavily traveled route accumulates over a service life of 30 or 40 years, exceeds anything currently considered in the design codes for such structures. The implications of this fact on the current inventory of such structures in similar installations and of the same age range, i.e., installed with the original interstate routes, largely in the 1960’s, are obvious.