Journal of Performance of Constructed Facilities

Performance-based seismic design (PBSD) is considered by many to be the next generation of design philosophy that focuses on the system performance of a structure during earthquake loading. For steel and concrete structures, this design philosophy is being used by a select group of practitioners. However, application to wood-frame buildings is still in the research stages; several approaches for PBSD are proposed with rehabilitation concepts available in ASCE 41. Currently, most of the PBSD methods for wood-frame buildings require designers to utilize a level of approach that is far more detailed than current design approaches. This increases the cost of any engineering for the design of wood-frame buildings. Therefore, in this study, a simplified design approach is developed that allows a designer to employ the PBSD methodology without complex analysis. Different from most existing PBSD procedures, this prescriptive approach was developed based on a significant number of numerical simulations using a simplified, nonlinear time history model that represented typical one- and two-story light-frame wood residential buildings. The final format of this simplified PBSD procedure is similar to the prescriptive tabular format in current design codes such as the National Design Specification for Wood (NDS). These tables enable selection of shear wall configuration based on a building’s performance expectation. Two design examples were used to illustrate this prescriptive PBSD procedure. Each of the final buildings designed using this procedure was then verified using a detailed nonlinear numerical model. The method was shown to be approximately 5 to 10% conservative, on average, from an exceedance probability standpoint for interstory drift limits.

Fire performance of steel structures is highly dependent on the effectiveness of applied fire insulation. However, insulation materials are susceptible to damage under extreme loading events. A state-of-the-art review on the role of insulation damage on fire resistance of steel structures is presented. Parametric studies on a six-story steel-framed building were carried out to illustrate the effect of insulation damage on fire response of a steel structure. In the analysis, realistic fire scenarios, loading, and failure criteria were taken into consideration. Analysis results indicate that the fire resistance of a steel-framed structure is significantly influenced by the extent of insulation loss, type of fire scenario, and level of lateral load. Insulation damage causes faster deterioration in the structural response of framed buildings under the combined effect of fire and lateral loading. The need for accounting for any insulation damage, arising under extreme loading events, in fire design of steel-framed structures is highlighted, and a performance-based design strategy incorporating fire resistance analysis is discussed.

The overall goal of this project was to design a wood frame shear wall that could withstand greater displacement before damage occurred to the gypsum wall board (GWB). A total of 14 shear walls consisting of seven different designs with two walls built per design were tested to failure. Six of these walls had $1,105\times 610\mathrm{mm}$ window openings and eight did not. Shear wall test behavior generally agreed with the ASCE/SEI 41-06 performance-based drift criteria. The results of the shear wall visual failure comparison indicated that all innovative shear wall designs outperformed the control designs at 1% drift. This was because less GWB damage was observed in the innovative shear wall designs. At 2 and 3% drift, two designs performed worse than the control. Three designs performed superior to the control designs at 2 and 3% drift. The greater performance of all these designs can be attributed to the increase in strength and stiffness of these shear walls. However, superior performance of the two designs was attributable to the similar stiffness of both sides of the shear wall, resulting in equal load sharing and less damage to the GWB.

In 2005, 15 adjacent box-beam bridges were randomly selected and inspected to document their performance with consideration of the evolving design procedures. Longitudinal cracking along the soffit of several fascia beams was documented. After evaluating inspection data, the bridge engineer recommended the replacement of a severely distressed fascia beam from the Hawkins Road Bridge in Jackson County, Michigan. The beam was salvaged and the capacity was evaluated through load testing. The remaining prestress was 75% of the initial prestress, which is 5% less than the final prestress used for the design. Concrete modulus of elasticity was evaluated as 35.4 GPa and the nominal compressive strength as 54.4 MPa. Analysis of load test data indicated that a bridge with the beam in this distressed state is safe to operate. This is assuming that the transverse connectivity between the beams is sufficient for load distribution as envisioned in the design. The importance of identifying concealed corrosion, and quantifying material properties and load distribution is highlighted in this paper.

This study was initiated after the sliding plate expansion joints of Millard E. Tydings Memorial Bridge, a long-span truss bridge, failed prematurely just a few months after their initial installation. The study included field investigation, material testing, analysis, and field testing. Test data records show numerous high spikes, which represent high tensile stresses, within their respective measured periods. By extrapolation, the failure was predicted by applying Miner’s linear cumulative damage rule. The calculation shows that the accumulative value would reach 1.0 when the first and subsequent failures were reported. The unexpected high stresses and poor workmanship caused early crack formation attributable to distress.

One of the latest solutions available for storm-water storage purposes is the underground chamber structure. Recently, a research team at Ohio University conducted a series of field load tests on the underground chambers. Four chamber structures were placed side by side in an excavated area, backfilled with coarse granular soil, buried under a soil cover of 0.46 m (18 in.), instrumented with sensors, and subjected to a series of controlled live load tests at a field project site. The sensor readings and visual inspection results indicate that the chamber with the specified minimum soil cover had no problem in supporting a wheel load of 52.3 kN (11.8 kips) and an axle load of 109.0 kN (24.5 kips) in both the transverse and longitudinal directions. Maximum reduction in the rise dimension was only approximately 2.3% when the chambers were subjected to the live loads. The vertical soil pressure readings measured at the chamber crowns were within 15% of the values given by a live load spreading formula included in the AASHTO LRFD specifications.

Central HVAC is a critical constructed facility in the built environment, yet polluted air quality has been causing environment, health, and safety problems to end-users worldwide, particularly in multistory commercial buildings with such systems installed. An index system was introduced in Hong Kong to measure the external air quality, but no system has yet been introduced for measuring internal air quality, nor the legislation to control it. The Hong Kong government states that more than 32% of commercial buildings and 37% of shopping arcades have sick building syndrome, which leads to nausea, dizziness, headaches, sore throats, nose irritation, sinus congestion, and other symptoms in the occupiers. In this study, the major causes, design, construction, users’ habitual modes, and mitigating measures will be investigated, with supporting case studies in Hong Kong. A preliminary investigation, air sample analysis, and end-users’ feedback from questionnaires will be gathered and analyzed to establish a long-term solution for air quality problems.

The investigation of dynamic response for civil engineering structures largely depends on a detailed understanding of their dynamic characteristics, such as the natural frequencies, mode shapes, and modal damping ratios. Dynamic characteristics of structures may be obtained numerically and experimentally. The finite-element method is widely used to model structural systems numerically. However, there are some uncertainties in numerical models. Material properties and boundary conditions may not be modeled correctly. There may be some microcracks in the structures, and these cracks may directly affect the modeling parameters. Modal testing gives correct uncertain modeling parameters that lead to better predictions of the dynamic behavior of a target structure. Therefore, dynamic behavior of special structures, such as minarets, should be determined with ambient vibration tests. The vibration test results may be used to update numerical models and to detect microcracks distributed along the structure. The operational modal analysis procedure consists of several phases. First, vibration tests are carried out, spectral functions are produced from raw measured acceleration records, dynamic characteristics are determined by analyzing processed spectral functions, and finally analytical models are calibrated or updated depending on experimental analysis results. In this study, an ambient vibration test is conducted on the minaret under natural excitations, such as wind effects and human movement. The dynamic response of the minaret is measured through an array of four trixial force-balanced accelerometers deployed along the whole length of the minaret. The raw measured data obtained from ambient vibration testing are analyzed with the SignalCAD program, which was developed in MATLAB. The employed system identification procedures are based on output-only measurements because the forcing functions are not available during ambient vibration tests. The ModalCAD program developed in MATLAB is used for dynamic characteristic identification. A three-dimensional model of the minaret is constructed, and its modal analysis is performed to obtain analytical frequencies and mode shapes by using the ANSYS finite-element program. The obtained system identification results have very good agreement, thus providing a reliable set of identified modal properties (natural frequencies, damping ratios, and mode shapes) of the structure, which can be used to calibrate finite-element models and as a baseline in health monitoring studies.