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.

Seismic vulnerability of a set of unreinforced masonry aggregated buildings of more than 70 years old located in Barcelona (Spain) is investigated. Four different model buildings are studied: they consist of three isolated buildings and one aggregated system, which are representative of most typical structural configurations used in the city. The aggregated building blocks are built individually without any gaps between them, thus interacting under lateral loads. The seismic hazard is described by the elastic response spectrum defined in Eurocode-8. Capacity curves are obtained using a nonlinear static analysis procedure; they are used to obtain the displacement-based fragility functions, the performance point, the probability damage matrices, and the mean damage factor, corresponding to the specified seismic action. In spite of the low-to-moderate seismic hazard in the region, the results show a high percentage of buildings having moderate and severe damage, depending on the soil type. Their brittle performance makes them seismically vulnerable. The overall behavior of the aggregate system is controlled by the fragility of the two corner buildings.

The response of dam structures subjected to explosion shock loading is a key element in assessments for the dam antiknock safety and antiterrorism applications. The physical processes during an explosive detonated in underwater/air and the subsequent response of structures are extremely complex, involving many complex issues such as the explosion, shock wave propagation, shock wave–structure interaction, and structural response. In addition, there exists a significant contrast in wave propagation phenomena in the water and the air medium due to their different physical properties and interface phenomena. In this paper, a fully coupled numerical approach with combined Lagrangian and Eulerian methods is used to simulate the dynamic responses of a concrete gravity dam subjected to underwater and air explosions. The shock wave propagation characteristics from explosions in water and air are simulated and compared. The damage profiles of concrete gravity dams subjected to underwater and air explosions are discussed. The influence of the blast loading from explosions in water and air on the dynamic response and the damage of the dam is also investigated. The analysis results show that a submerged explosion causes significantly more damage to the dam in water than the same mass of explosive in air.

Movements and lateral earth pressure of integral abutment bridges are mainly affected by seasonal thermal variations. To investigate this aspect, a test bridge was constructed with integral abutments as stub type abutments founded on flexible piles, and abutment movement, earth pressure, and thermal exchange were monitored from 2000 to 2002. Based on long-term monitoring of the test bridge, several relationships for integral abutments, which are the relationships between abutment movement and thermal exchange, abutment movement and earth pressure, and earth pressure and thermal exchange, were proposed. In addition, a three-dimensional finite-element study was conducted to verify the moving behavior of the integral abutment, and its results showed that the integral abutment had rotated and laterally displaced.

In this paper, a series of joint tests and full-scale structural tests were performed to assess the effectiveness of pultruded glass fiber-reinforced polymer (GFRP) profiles for rehabilitating lattice steel columns. The data for the displacements and strains of typical members were recorded. The experimental results showed that the failure modes are generally identical for the original column, the column restored using angles, and the column that adopted the stiffer GFRP-to-steel bolted joints (using steel cover plates, bolts, and nuts) repaired with pultruded GFRP sections. In contrast, the failure pattern of the column that used the ordinary GFRP-to-steel bolted joints (only using bolts and nuts) was not the same. Additionally, the ultimate strength of the specimen that employed the stiffer GFRP-to-steel connections was slightly higher than that of the specimen retrofitted by angles, and the ultimate capacity of the sample that adopted the ordinary GFRP-to-steel connections was significantly lower than that of the sample restored by angles because of the premature failure of the ordinary GFRP-to-steel connections. Additionally, better coordination in the working capacity of the GFRP members was exhibited by the restored structure. Furthermore, joint slippage dramatically decreased the stiffness of the structure, and its influence on the load-bearing capacity and failure mode is not obvious if the structure is subjected to the transverse loading. The conclusion is that pultruded GFRP profiles can be used for retrofitting of lattice steel structures and that the performance of GFRP-to-steel connections is a key factor in this novel method. This preliminary investigation into the feasibility of using pultruded GFRP profiles in the repair of lattice steel structures shows promising results and provides a basis for the development of other FRP shapes for application in the rehabilitation of lattice steel structures.

Trenchless rehabilitation techniques such as cured-in-place pipe (CIPP) had been adopted by many municipalities in the province of Quebec to renew their aging sewer systems. Currently CIPP represents the largest market share of the utilized trenchless rehabilitation techniques in the province of Quebec. Considerable funding is being directed towards sewer systems rehabilitation projects. However, there have been little studies on the performance of the rehabilitated sewers, expected life of the liner, and its structural properties. Therefore, in an effort to address this shortcoming, this paper presents the outcome of a destructive testing protocol conducted on liners samples extracted from sewers rehabilitated using CIPP. Samples used in the testing process were collected from two locations in the sewer network that were rehabilitated over 1 decade ago. Testing the liner included examining the physical properties (e.g., thickness, annular gap, and so on), flexural properties, and tensile properties. The results demonstrate excellent current structural properties and strongly indicate that the liner will meet the anticipated lifetime. Deterioration of liner is expected to take place at a low rate. This conclusion remains valid as long as the current factors influencing structural properties do not change drastically over time.

Four metro stations with similar supporting systems and pit geometries in Shanghai soft clay were excavated using different soil removal procedures, which led to distinctly different pit behaviors. Through analyzing and comparing the well-documented field data from these four bottom-up excavations, the significances of quick excavation, promptly propping, timely casting of floor slabs, and segmented construction in control of pit deformations were identified and their influences were comprehensively quantified. As to these four pits, the measured time-dependent wall deflections and wall heaves in 20–35 days at relatively deep excavation levels were up to 47–94% the magnitudes at completion of excavation to the final depths. The measured postexcavation wall deflections in about 20–30 days were up to 36–45% the maximum wall deflections at completion of excavation and the corresponding postexcavation deflection rates were up to twice those during excavation. The poorly excavated pits, which featured long excavation duration, long wall exposure lengths, or delay in propping struts or casting floor slabs, experienced wall deflections and ground settlements $1–4$ times greater than the appropriately excavated pit. The wall deflection rates of the poorly excavated pits were up to $2–3\times$ and $4–6\times$ those of the appropriately excavated pit during and after excavation, respectively. Compared with the countermeasure of increasing supporting system stiffness by casting rigid concrete struts and/or bracing double steel pipe struts at one level, the approach of quick excavation, promptly propping, and timely casting of rigid floor slabs in combination with a segmented construction procedure was demonstrated to be much more efficient in controlling excavation-induced deformations.

The corrosion performance of epoxy-coated bars in four bridge decks built in the 1970s is evaluated. The study includes data from two separate investigations conducted 10 years apart; it is based on data obtained from in situ inspections and laboratory tests. The data show that after approximately 30 years of service, the decks were all in good condition. They showed light cracking and few delaminated areas (some of which have already been patched), and only one deck had an open spall. Nonetheless, evidence of corrosion activity was found at various locations in all four decks, especially near or at expansion joints, or where cracks had developed. At these locations, chloride ion concentrations at the bar-level were high [${3\mathrm{kg}/\mathrm{m}}^3$ ($5\mathrm{lb}/\mathrm{cu}\mathrm{yd}$) or greater], and the severed bars showed minor rust buildup on the surface. Away from joints or cracks, however, epoxy-coated bars typically showed zero or light corrosion with low bar-level chloride ion concentrations in the concrete.

Support bearings have a very important role in the structural performance of bridges. As an integral part of the bridge, bearings must guarantee a service life that is compatible with that of the remaining bridge components. However, the service life of support bearings is often lower than that of the bridge, leading to repair or replacement operations, which can be relatively expensive and may cause considerable inconvenience to the traffic flow. This paper follows a recent study performed by the authors, in which an inspection and diagnosis system for road bridge structural bearings was proposed. It presents the application of the system to a sample of 152 support bearings in Portuguese road bridges, which is also deemed representative of bridge bearings in most European countries. The results obtained allowed performing a statistical analysis in which a number of aspects were evaluated, namely, the characteristics of the bearings, the anomalies, their causes and degree of urgency of intervention, the inspection and diagnosis methods, and the most appropriate maintenance and rehabilitation techniques. The results obtained allow characterizing and understanding in further depth the behavior of these bridge components, providing a number of lessons on bridge bearing design, execution, and maintenance.

In this study the seismic performances of the fixed-base jacket structures with various bracing configurations were evaluated by nonlinear static and dynamic methods, and the effects of various retrofit schemes were compared. It was observed that the conventional retrofit methods of increasing member size were somewhat effective in increasing the strength of fixed steel jacket platform structures but were not so effective in increasing ductility. However, the ductility of the structures retrofitted with buckling-restrained braces turned out to be increased significantly. In the structures with conventional bracing, plastic hinges or buckling generally occurred at the upper half of the jacket structures. On the contrary, they were more uniformly distributed along the structure height in the structure retrofitted using buckling restrained braces. The capacity curves obtained from incremental dynamic analysis generally corresponded well with those obtained from nonlinear static analysis using a lateral load pattern proportional to the first mode shape of the jacket structure.

The authors present their own experimental studies, which include research on a reinforced-concrete cylindrical tank with a nominal unit capacity of $\mathrm{8,300}{\text{m}}^3$, located in the sewage treatment plant in Krakow, Poland. The wall is monolithically connected to the foundation ring and was concreted in two stages: every second segment. This tank is classified among semimassive structures, which, owing to its volume and geometry, has an ability to store up a greater amount of released heat during the hardening process. At the stage of tank erection, because of cracks, numerous cases of leakage through the tank wall appeared. The measurement of longitudinal concrete deformation and crack development, together with the crack widths in selected segments, are presented. Moreover, the measurement of strains and crack-width propagation in vertical construction joints among three selected segments are discussed. The research presented provides information about the real behavior of such a structure under construction. In the subsequent paper (Part II), the results from experimental studies will be compared with the results obtained from an advanced numerical model.

The subject of this paper is a phase numerical analysis of early-age cracking of a reinforced concrete (RC) cylindrical tank wall, with a nominal unit capacity of ${\mathrm{8,300}\mathrm{m}}^3$, under construction. Numerical calculations are based on the model that can analyze the behavior of such structures, including the temperature development originating from heat hydration, external conditions, the development of shrinkage, and mechanical properties in time. A viscous-elastic concrete model with cracking was used. The real state of cracked wall segments 8 and 9 (Part I) is compared with the results of the numerical calculations. Moreover, the cracks’ localization and sequence of cracking as a result of the numerical analysis is discussed. Based on the achieved numerical results, the design solutions of vertical construction joints in which the degree of reinforcement is increased to ensure their water-tightness (despite the use of a sealing tape) negatively affect the cracking state of the jointed walls. This is reflected in the extended cracking that leads to the occurrence of leakage.

Evaluating the condition of concrete bridge decks is an increasingly important challenge for transportation agencies and bridge inspection teams. Closing the bridge to traffic, safety, and time consuming data collection are some of the major issues during a visual or in-depth bridge inspection. To date, several nondestructive testing technologies have shown promise in detecting subsurface deteriorations. However, the main challenge is to develop a data acquisition and analysis system to obtain and integrate both surface and subsurface bridge health indicators at higher speeds. Recent developments in imaging technologies for bridge decks and higher-end cameras allow for faster image collection while driving over the bridge deck. This paper will focus on deploying nondestructive imaging technologies such as the three-dimensional (3D) optical bridge evaluation system (3DOBS) and thermal infrared (IR) imagery on a bridge deck to yield both surface and subsurface indicators of condition, respectively. Spall and delamination maps were generated from the optical and thermal IR images. Integration of the maps into ArcGIS, a professional geographic information system (GIS), allowed for a streamlined analysis that included integrating and combining the results of the complimentary technologies. Finally, ground truth information was gathered through coring several locations on a bridge deck to validate the results obtained by nondestructive evaluation. This study confirms the feasibility of combining the bridge inspection results in ArcGIS and provides additional evidence to suggest that thermal infrared imagery provides similar results to chain dragging for bridge inspection.

Buildings can be poorly maintained because of lack of understanding about the role of building maintenance in achieving the organization’s objective and long-term profitability. The maintenance management is the agent that provides maintenance services to fulfill the needs of the organization. However, involvement of all of the key participants is the key to enhance maintenance planning, execution, and outcome whereby the participative mechanism involves the key participants dealing with the maintenance issues. Thus, this paper seeks to identify the participative mechanisms through a literature review. Then, a relationship between the mechanisms and maintenance performance through a questionnaire survey and interview is established. Finally, a regression model for prediction purposes is produced. The findings reveal that effective communication among the key participants is vital to enhance the maintenance performance. Therefore, this paper recommends that management should develop an effective communication platform involving all key participants, with contribution and commitment toward the maintenance activities.

Tongue-and-groove plank wood decking is a product that is commonly used in post and beam timber construction to transfer gravity loads on roofs and floors. In 2010, the National Building Code of Canada changed the application area of the specified concentrated roof live loads from $750\times 750\mathrm{mm}$ to $200\times 200\mathrm{mm}$. Preliminary analysis showed that the change in the application area of concentrated loads would have a significant impact on the design of decking systems. An experimental program was undertaken at the University of Ottawa’s structural laboratory to better understand the stiffness characteristics of plank decking under concentrated loads. The experimental test program was complimented with a detailed finite-element model in order to predict the behavior of a plank decking system, especially the force transfer between decks through the tongue and groove joint. The study found that under concentrated loads, the stiffness of the decking system increased significantly as more boards were added. The number of boards found to be representative of a system was eight boards. A deflection coefficient of $\gamma =0.4$ was found to be appropriate to calculate the deflection for the simple span, two-span continuous, and controlled random layup, under concentrated load on an area of 200 by 200 mm. A finite-element model was created and compared with the experimental results, and it was found to predict the behavior with reasonable accuracy.

An experimental program was undertaken at the University of Ottawa’s structural laboratory to investigate the behavior of plank decking under uniformly distributed loads. Nondestructive and destructive tests were conducted on plank decking systems to investigate their stiffness and failure mode characteristics. The study showed that the established deflection coefficients used to check the deflection of plank decking under balanced uniformly distributed loads can be conservatively used to estimate the stiffness of the simple span, two-span continuous, and controlled random layup patterns. It was also found that a deflection coefficient of 0.60 would be suitable for the combination simple and two-span continuous layup. Under unbalanced loading on two-span continuous layups, it was found that the deflection coefficient of 0.42 was nonconservative and that a more appropriate value to use in this case would be 0.60. The failure mode of a controlled random layup decking system under a uniformly distributed load was found to be consistent with the failure observed for simple span. The assumption of basing the capacity of the controlled random layup on the capacity of simple span layup seems appropriate.

Sustainable development studies have recently begun to consider damage loss attributable to natural hazards. A sustainable perspective on building design entails an understanding of a structure’s life-cycle environmental costs and consideration of the associated environmental impacts induced by natural hazards. Damage repair costs lead to additional material and energy consumption, creating harmful environmental impacts. Merging the results obtained from a natural hazard evaluation and related environmental impacts for buildings in seismically prone areas provides a novel outlook for sustainable design decisions. To evaluate the environmental impacts caused by buildings, the long-term effects accrued throughout a building’s lifetime and the effects associated with damage repair need to be quantified. A literature review and a proposed method for this type of analysis have been developed and are discussed. Using Athena and HAZUS-MH software, this study evaluated the performance of steel and concrete buildings by considering their life-cycle assessments and earthquake resistance. This study determined that code design level greatly affects building repair and damage estimations. This study presented two case-study buildings and found specific results using several assumptions. Future research recommendations were provided to make this methodology more useful in real-world applications. Examining the cost and environmental impacts of a building using a cradle-to-grave analysis and seismic damage assessment assists in reducing material consumption and construction activities before and after an earthquake event occurs.

Communication and coordination are key issues for successful project management. Coordination is specifically a challenging task for industrial projects where a number of interdependent role players are needed to achieve the desired project outcomes. In this context, a two-stage case study of construction phase delay control for an oil and gas industrial project is presented. A process improvement methodology was carried out in the first stage and the root causes for the delays were identified. The investigation results revealed that the scope of one item of work, piping, dominated a large portion of delays. It was found that piping packages were not processed smoothly due to four main causes: incomplete testing, frequent piping modifications, incomplete as-built drawings, and incomplete punch listing. Seventy percent of the delays were caused by incomplete testing activities and incomplete as-built drawings. The improvement study suggested establishing a new unit for piping test package control and coordination. The review process was improved and the dedicated control team was implemented for the second unit, resulting in a substantial drop in the number of delayed test packages (down from 48 to 8%) and punch list items (down from 3,075 to 2,371). The findings of the case study demonstrate the importance of communication and coordination in successful project management for complex projects. The case presented is an example of process improvement use for successful delay management.

The number of permits for superheavy loads crossing Texas bridges has steadily increased over the years, and compared with several other states, the criteria that establish superheavy-load status are generous. The result is that many Texas bridges experience high-stress loads that cause accelerated deterioration. In this study, bridge load and rating factors and the validity of the criteria for establishing superheavy-load status are evaluated. The primary objective of this study was to evaluate Texas superheavy-load criteria for bridges. To accomplish this, field tests for the response behavior of a bridge subjected to overweight vehicles and a parametric study using finite element analysis were utilized to extract bridge criteria triggers. The field-verified solid model and related parametric study show that the Texas superheavy-load criteria are valid for the study bridge type. Load ratings computed using the distribution factors determined in this study show that the evaluated bridge has much reserve capacity, even for short 1,023 kN (230 kip) and longer 1,383 kN (311 kip) superheavy loads. The parametric study using finite element modeling shows that the criteria adequately protect this bridge type. Because the criteria are based on prior permitting by Texas Department of Transportation (TxDOT), a graphical version of the criteria might serve TxDOT and carriers better than do the gross vehicle weight limits alone. Long term collection of load frequency and load level data from a relevant bridge would help TxDOT determine the effects stress level variations have on the life of Texas bridges.

Throughout the U.S., there has been a dramatic increase in the installation of wind turbines, which and are now producing a notable portion of renewable energy. The tower base experiences large stress reversals as a result of wind loading and can be subjected to fatigue failure if not properly designed. In this study, fatigue life estimates for wind turbine tower bases throughout Colorado are investigated and the effects of wind distribution and turbulence intensity of those estimates are discussed. The concept of performance-based design (PBD) is applied to optimize the tower base design parameters such that the desired fatigue life is achieved with a minimum amount of steel used in the design. It is concluded that the application of PBD may substantially reduce the initial cost of wind turbine startup, i.e., design and construction, thereby reducing the cost of wind power.

The response of a blast mitigation cladding consisting of a face sheet and metal foam core subjected to a close-range blast is predicted. Whereas the cladding is sufficiently wide compared to the standoff distance between the explosion center and the cladding, the boundary of the blast induced bulge is released. The face sheet is considered as a rigid perfectly plastic membrane as the deformation of the sheet always exceeds half its thickness. A procedure predicting the depth and extent of the bulge is proposed with energy method. Subsequently, the minimum thickness of the foam layer is calculated based on the bulge depth. This design-oriented approach, in a ready-to-use manner, can be straightforwardly applied, facilitating the preliminary design of blast mitigation claddings with metal foam core.

Seismic retrofitting of unreinforced masonry buildings using posttensioning has been the topic of many recent experimental research projects. However, the performance of such retrofit designs in actual design-level earthquakes has previously been poorly documented. In 1984, two stone masonry buildings within The Arts Centre of Christchurch received posttensioned seismic retrofits, which were subsequently subjected to design level seismic loads during the 2010/2011 Canterbury earthquake sequence. These 26-year-old retrofits were part of a global scheme to strengthen and secure the historic building complex and were subject to considerable budgetary constraints. Given the limited resources available at the time of construction and the current degraded state of the steel posttension tendons, the posttensioned retrofits performed well in preventing major damage to the overall structure of the two buildings in the Canterbury earthquakes. When compared to other similar unretrofitted structures within The Arts Centre, it is demonstrated that the posttensioning significantly improved the in-plane and out-of-plane wall strength and the ability to limit residual wall displacements. The history of The Arts Centre buildings and the details of the Canterbury earthquakes is discussed, followed by examination of the performance of the posttension retrofits and the suitability of this technique for future retrofitting of other historic unreinforced masonry buildings.

An analysis until the failure on a series of one-way slabs with severe corrosion at the lower reinforcement of the RC joists is presented. Different positions in the slab and number of damaged joists have been studied, obtaining the residual safety assessment in cases of slabs damaged by flexural failure mechanisms. Since the boundary conditions have proved decisive for obtaining the behavior, the damaged slab has been evaluated as part of the entire building, as precisely as possible, taking into account the different phases of the construction process and deterioration in time, and the complex behavior of concrete, steel and masonry. The results of the proposed methodology are consistent with the pathology of the observed cases. As a result of this study the authors propose practical recommendations to help in making decisions about the magnitude of the intervention, always necessary in this type of pathology.

This paper presents the results of large-deflection resistance testing of partially grouted single-wythe and multiwythe insulated masonry walls. Three design sections were evaluated under uniform pressure in a vacuum chamber test, as follows: (1) 150-mm (6-in.) standard block masonry wall reinforced with 10-mm (No. 3) rebar at 80-cm (32-in.) maximum spacing; (2) 200-mm (8-in.) standard block masonry wall reinforced with 13-mm (No. 4) rebar at 120-cm (48-in.) maximum spacing; and (3) a cavity wall consisting of 200-mm (8-in.) standard reinforced concrete masonry unit (CMU) wythe, a 100-mm (4-in.) clay facing brick veneer with 50-mm (2-in.)-thick extruded polystyrene rigid board insulation, and a 25-mm (1-in.) air gap between the structural wythe and the veneer. Each test panel was $3.5\text{-}\mathrm{m}(136\text{-}\mathrm{in.})\text{wide}\times 3.0\text{-}\mathrm{m}(116\text{-}\mathrm{in.})\text{high}$ with only the cells containing reinforcement grouted. Displacement at several locations through the height and width of each panel were recorded as each test panel was loaded to collapse. Interior and exterior videography was also used to record the progression of cracking and failure. The failure mechanisms demonstrated the expected tension cracking due to flexure and a ductile flexural response was observed with rotations up to approximately 20°. The resistance function results were plotted and assessed against the resistance definitions assumed by commonly used blast design methodologies, and it was demonstrated that the flexural design resistances used in blast analysis single degree of freedom methodology are conservative. Furthermore, since the 200-mm (8-in.) thick single-wythe wall and the veneer wall had the same structural wythe designs, the stabilizing effects provided by the clay brick veneer and cavity wall components was demonstrated. The resistances and failure modes will subsequently be compared in the companion paper against those encountered in full-scale blast tests involving the same masonry panel designs.

This paper presents the results of full-scale blast load testing of partially grouted single-wythe and multiwythe insulated masonry walls. Three design sections were evaluated, as follows: (1) a 150-mm (6-in.) standard block masonry wall reinforced with 10-mm (No. 3) rebar at 80-cm (32-in.) maximum spacing, (2) a 200-mm (8-in.) standard block masonry wall reinforced with 13-mm (No. 4) rebar at 122-cm (48-in.) maximum spacing, and (3) a cavity wall consisting of 200-mm (8-in.) standard reinforced concrete masonry unit (CMU) wythe plus a 102-cm (4-in.) clay facing brick veneer with 52-mm (2-in.) thick extruded polystyrene rigid board insulation and a 25-mm (1-in.) air gap between the structural wythe and the veneer. Each test panel was 285 cm (112 in.), seven blocks, in $\text{width}\times 345\mathrm{cm}$ (136 in.), 17 courses, in height. Only the cells containing reinforcement were grouted. Three blast load experiments were conducted; each experiment tested one each of the three test panel designs. The loading varied significantly between each of the three experiments. Dynamic displacement at several locations through the height (quarter points) of each panel was recorded. The reflected pressures, free field pressures, and internal pressures were recorded at several locations. Interior and exterior videography was also used to record the response. A detailed posttest forensic evaluation was conducted to determine predominant failure mechanisms. The measured transient deflection responses were then compared to analytical responses calculated using the static resistance functions generated from the test results presented in the companion paper as well as by typical blast design methodologies. The comparisons demonstrated that the design resistances used in blast analysis single degree of freedom methodology are conservative. However, the blast testing demonstrated that potentially dangerous modes of localized failure between the grouted cells can occur at scaled distances that are significantly greater than scaled distances that would be assumed to cause breaching.

Masonry flat arch diaphragm that developed in Britain is still in use in parts of Europe, North America, the Middle East, and Indian subcontinent. The damage of a large number of these diaphragms during past earthquakes all around the world highlighted the need for developing an appropriate retrofitting method. In this study, the in-plane seismic behavior of ordinary and the retrofitted brick flat arch diaphragms are experimentally investigated. Eight full-scale experiments were conducted under cyclic loading. Perpendicular and parallel loads were applied to the steel I-cross beams of the masonry flat arch diaphragms. The experimental models consisted of two frames of masonry flat arch diaphragms in the absence of brick flat arch, two ordinary masonry flat arch diaphragms with steel tension ties in end arch spans as prototype, two masonry flat arch diaphragms without and with steel tension ties in diaphragm span, and two retrofitted masonry flat arch diaphragms with simultaneous use of steel diagonal bracing and steel tension ties in end arch spans. The results of the experiments demonstrate that the ordinary masonry flat arch diaphragms have insufficient shear capacity and integrity. However, among the retrofitted models, the simultaneous use of diagonal bracing and steel tension ties in end arch spans improved the overall seismic performance, integrity, and ductility of the masonry flat arch diaphragm. Moreover, the stiffness and shear capacity of this diaphragm increased up to 108 and 88%, respectively. The findings of this study recommend the use of simultaneous diagonal bracing and steel tension ties in end arch spans for retrofitting the ordinary masonry flat arch diaphragms.

Nowadays, modern analysis of civil engineering structures implies the use of increasingly sophisticated computer models, designed not only to predict the response of actual structures to different loadings, but also to simulate the effects of eventual modifications in their structural configuration. Nevertheless, it is often discovered that when the numerical simulations are compared with experimental data, the degree of correlation is weak, thus preventing the use of the finite-element (FE) models with confidence in further analyses. In such cases, FE updating techniques are available to correct the FE models, based on dynamic response records of the real structures. These updating processes usually consist of four phases: preliminary FE modeling, experimental modal identification, manual sensitivity analysis and, finally, updating the FE model. The present paper presents all four phases of a successful updating process for the FE model of a footbridge structure. It is shown how the last phase of the process can be performed fully automatically by coupling an optimization routine with a commercial FE analysis program.

A three-span-continuous girder bridge has to be integrally lifted by 3 m to meet increased navigation capacity. This paper mainly introduces the lifting system mechanism, construction process, and bridge jack-up monitoring. To determine the control threshold value during the construction process and to ensure the safety of successive lifting, a three-dimensional finite-element model is established to analyze the strain and stress distribution characteristics of the bridge. With guidance from the numerical analyses, the three-continuous-span girder bridge is lifted successfully. The design and construction methods adopted in this project provide a useful reference for similar engineering projects.

Commercial buildings, which are ubiquitous in metropolises, are typically equipped with a wide range of facilities. Satisfactory operation of the facilities necessitates provision of effective maintenance works in the long run. Since, fully computerized maintenance management systems are seldom adopted for facilities in commercial buildings, the dearth of proper maintenance data makes it difficult to investigate their maintenance performance. Reported in this paper is an examination of the maintenance data of a large commercial building, which were recorded semi-automatically by a computer-aided maintenance system. The maintenance works were found to be mainly corrective in nature, dominated by the electrical trade. Existing occupancy and business operation were influential to the issue time of the work orders. Benchmarks of response time, repair time, and downtime were established for evaluation and benchmarking purposes. Further works are needed to probe into the factors that affect maintenance performance, especially the effectiveness of maintenance manpower deployment.

Building defects are an important aspect to address to enhance the quality of homes. However, there is limited knowledge of defects of posthandover new-build homes. This paper aims to examine the profile of building defects in number, type, location, and severity and investigate their influencing factors, including building type, floor area, number of bedrooms, build method, and performance standard. Data were collected using defect records for 327 homes in the United Kingdom (U.K.) during the defects liability period of 12 months posthandover. In total, 3,209 defects were identified and examined. The results indicate that the defect profile of UK post-2006 new-build homes has improved in the number, diversity, and severity of defects. Kitchens and bathrooms remained the two most defective areas. Larger houses were found to be significantly more defective than smaller flats. However, no clear relationship was observed between the defect profile of the dwellings and their build method or performance standard adopted. The findings shed light on the understanding of the profile of building defects and should support their better predictability and control in future practices.

Proposed herein is a method for load rating of prestressed box beam (PSBB) bridges based on their dynamic response collected using wireless sensor networks (WSNs). The hypothesis states that the health of a bridge is associated with its vibration signatures. Two WSNs were deployed on a 25-year-old PSBB bridge, and trucks were run with variable loads and speeds for collecting its real-time dynamic response at current condition. Also performed were finite-element (FE) simulations of 3D bridge models under vehicular loads to acquire the representative dynamic response at its newest condition. The bridge model was validated by field testing and numerical analysis. The fast Fourier transform and peak-picking algorithms were used to find maximum peak amplitudes and their corresponding frequencies. The in-service stiffness of the bridge was calculated to determine its load rating, which resembles the actual load rating of the bridge. The application software developed from this research can instantly determine the load rating of a PSBB bridge by collecting its real-time dynamic response. The research outcome will help reduce bridge maintenance costs and increase public safety.

This paper describes a modification to the layered-sectional analysis approach, which provides the engineer with a tool to assess structural behavior of concrete beams with localized damage, a problem not well suited to classical, closed-form solutions. The modified layered-sectional analysis (MLSA) framework is applied to a forensic investigation case study in which two prestressed double-tee beams are exposed to a short duration, intense fire in a parking structure. The results of the MLSA are within 1% of the case study load test, which indicates that the MLSA could be a useful, computationally efficient tool for the investigating engineer to predict the postfire serviceability and strength of damaged beams, and potentially eliminate the need for expensive load testing. A short parametric study is included for the research engineer interested in the MLSA for predicting the postdamage behavior of non-standard materials such as enhanced sustainability concrete (ESC).

Recently, mainland China has experienced the fastest urbanization in the world; however, the development of structural regulations regarding facility management (FM) services for housing is relatively recessive. As a result, disputes and conflicts in facility management of the private housing sector have become a serious problem in urban communities, affecting social sustainable development of the building industry. Comparatively, the private housing FM system in the urban areas in the Taiwan region was developed much earlier; thus, it is more advanced and mature than that in mainland China. This paper intends to compare the FM sectors between the two regions to provide suggestions for improving the service quality of the FM system in mainland China.