Journal of Performance of Constructed Facilities

This paper describes the collapse during construction of a precast concrete girder bridge crossing Highway 15, north of Montréal. The bearing conditions for the girders at the time of collapse are discussed. The tie rods that were used to restrain the movement of the girder top flanges were tested to determine their effective stiffness and strength. Rotational and sliding tests were also performed on the pot bearing units. These experimental results were used in an analytical study to confirm the sequence of collapse of the girders. Bracing requirements during construction for precast girder bridges supported on pot bearings are discussed.

One of the greatest challenges facing municipal engineers is the condition rating of buried infrastructure assets, particularly water mains. This is because water mains are typically underground, operated under pressure, and usually inaccessible. Condition rating is a mandatory process to establish and employ management strategies for any asset. To assess the condition of water mains, current research considers physical, environmental, and operational factors and their effect on different types of mains (i.e., cast iron, ductile iron, and asbestos). A condition rating model is developed to assess and set up rehabilitation priority for water mains using the artificial neural network (ANN) approach. Data are collected from different municipalities to train the developed model. The ANN input factors incorporate pipe type, size, age, breakage rate, Hazen-Williams factor, excavation depth, soil type, and top road surface; however, the output is pipe condition. The trained ANN shows robust performance (learning $\text{rate}=0.005$ , $R^2=0.931$ , correlation coefficient $r=0.9653$ ). Results show that the breakage rate has the highest relative contribution factor among the others. The developed model is relevant to researchers and practitioners (municipal engineers, consultants, and contractors) in order to prioritize pipe inspection and rehabilitation planning for existing water mains.

With an alarmingly increased rate of deterioration in reinforced concrete structures due to durability performance, efforts are being made to quantify in situ performance. Performance is a function of time and it is related to degradation and the parameters influencing it. Although state-of-the-art modeling of various deterioration mechanisms is available in the literature, evaluation of the influence of various deterioration mechanisms that decrease performance with time is difficult. However, in situ condition documentation, survey, and assessment of deteriorated structures reflect the resultant deterioration process and also helps in validation of experimental and theoretical methods of performance evaluation. In this research, a systematic in situ condition documentation, survey, and assessment of water tank structures has been done based on an empirical damage scale similar to that suggested in the literature and a bilinear graphical deterioration model for such water retaining structures in a semitropical region like India is presented on the basis of case studies.

Bridge management systems have adopted Markov-chain models for predicting the future condition of bridge components, systems, and networks. These models are developed based on two assumptions. First, bridge inspections are performed at predetermined and fixed time intervals (i.e., constant inspection period). Second, the future bridge condition depends only on the present condition and not on the past condition (i.e., state independence). This paper evaluates the impact of these assumptions on the performance prediction of bridge deck systems using field data obtained from the Ministère des Transports du Québec. Transition probability matrices are developed for the different elements of the deck system and adjusted for the variation in the inspection period using Bayes’ rule. This investigation indicated that the variation in the inspection period may result in a 22% error in predicting the service life of a bridge deck system. Also, the statistical tests used to assess the validity of the state independence assumption of Markov chains showed that this assumption is acceptable with a 95% level of confidence, which is reasonable for network level analysis.

Plain jointed concrete pavements laid in Mumbai City (India) during the early 1990s were structurally evaluated using a falling weight deflectometer (FWD) and testing of concrete cores extracted from the pavement slabs. The ultrasonic pulse velocity (UPV) of the concrete in the cores was determined first and then the cores were crushed under compression. The pavement deflections were found to be within the limits as suggested in the Indian codes and the international literature. The joint conditions were also found to be satisfactory. The design strength of the concrete was back-calculated from the compressive strength of the cores and was found to conform to the design specifications. However, the construction quality was found wanting as the thickness of pavement slabs at a few locations was lower than that specified and it has resulted in cracking of the slabs. The dynamic modulus of elasticity of concrete as determined by the FWD was found to correspond well with that computed from the UPV of cores and from the compressive strength of concrete. A method is suggested to estimate the structural parameters of uncracked pavement slabs from the dynamic modulus of elasticity obtained through the indirect method of UPV testing which is less expensive compared to evaluation by the FWD.

Longitudinal joint cracking is one of the most prevalent forms of distress in asphalt concrete pavements. The joint area does not achieve the same density as the mat due to an unconfined edge on the initial pass and a cold joint during the second pass. The lower density allows water to penetrate and the material cracks, usually within $\text{one}\text{year}$ of construction. There are many techniques for constructing longitudinal joints, one being to preheat the joint prior to paving the second lane. This paper describes a field study conducted in New Hampshire using an infrared joint heater. Thermocouples were embedded in the pavement to determine the extent of heat penetration from the infrared heaters. Cores were taken along the joint and in the travel lanes for both the control and test sections. Density and strength measurements were taken on the cores. Permeability measurements along the control and test joints were performed. A cracking survey performed $\text{one}\text{year}$ after construction showed that the section of pavement where the infrared heater was used had significantly less cracking than the control section.

Woodframe structures represent the most common structure type within the residential building stock in the United States. These relatively light structures perform well with regard to life safety and collapse during earthquakes, but can be significantly damaged resulting in large financial losses. Societal demands for damage-limiting design philosophies in the wake of the Northridge earthquake have fueled researchers (and practitioners) need to understand and better predict damage to woodframe structures. This paper examines damage to the lateral load carrying assemblies within woodframe structures, namely shearwalls. This is presented within the context of damage prediction for a wood shearwall assembly, and shortcomings and needs of such an approach are subsequently addressed. The incremental dynamic analysis approach is also examined as a possible tool for damage prediction. Qualitative damage descriptions and seismic force demands matched very well while maximum transient drifts did not match experimental results well. The potential for development of a whole-structure predictive damage model and its integration into the development of a performance-based seismic design development for woodframe structures is examined.

The present study aims at investigating the applicability of the Florida Building Code (FBC) wind provisions and demonstrating benefits of the shuttering on the openings in the Florida House Learning Center, a unique demonstration structure with a large number of windows and sliding glass doors. The wind analysis of the building was performed according to the FBC on the currently existing structure with no hurricane shutters and on the strengthened structure with hurricane shutters added to all openings. It was found that wind pressures on walls and roofs for the unshuttered Florida House structure decreased by 0–95% due to the addition of hurricane shuttering. The reduction of the design forces for wall studs, anchor bolts, and uplift varies from 0 to 38% due to the addition of shutters. The only reason for wind pressure differences on the shuttered and unshuttered Florida House structure was the difference between the internal pressures on the “enclosed” and “partially enclosed” buildings, respectively. The significant hurricane mitigation effects of hurricane shutters on the Florida House hurricane vulnerability is demonstrated through the comparison of wind analysis between the shuttered and unshuttered structure.

Design defects are experienced in many projects; the difference is only in the extent of occurrence. This technical note discusses a design error case in a building project in Nepal, where the designer made the wrong assumptions in roof treatment work for waterproofing as well as for heat insulation purposes. From the investigation of the problem, it was found that the waterproofing polymer was not applied directly over concrete slab top. Use of heavy concrete block as a heat insulation material also helped to increase the leakage problem. The problem evoked loss of prestige for project officials, the design consortium, and the contractor.

Tests were conducted to measure the fundamental frequencies of reinforced concrete beams. Beams were tested prior to load application and after they had been loaded to various fractions of their ultimate moment capacity. Dynamic testing was performed in an unloaded state in both the direction of loading and in the direction perpendicular to loading. Resulting fundamental frequencies were used to determine the dynamic flexural stiffness $\left(E_{d}I\right)$ relative to the undamaged flexural stiffness. Results show that fundamental frequency tests can effectively measure decreases in dynamic flexural stiffness caused by flexural cracking. However, the effective moment of inertia in the relaxed state is not accurately predicted by American Concrete Institute recommendations for computing static beam deflections. Equations were developed to describe the effective flexural stiffness of unloaded, cracked beams. A relative dynamic flexural stiffness value of 70 provides a conservative prediction that a beam has failed by being loaded to its ultimate moment capacity.