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The 2018 M7.1 Anchorage earthquake damaged over 120 schools in the Anchorage and Matanuska-Susitna (Mat-Su) School Districts. Many remained closed for a week or more for cleanup and repairs, primarily due to nonstructural damage. Major structural damage occurred in three of 132 school buildings across both districts, and a number of additional schools had minor to moderate damage. Most observed damage was to nonstructural components, including suspended ceilings, lighting, architectural finishes, building utility systems, and equipment. Middle and high schools were in session at the time of the earthquake. Despite ceiling damage and fallen ceiling tiles, books, and supplies (heavy furniture was anchored) and objects swinging from the ceiling, both districts reported very few injuries. Statements by the school districts and administrators, media reports, and available video indicate that most students dropped, covered, and held on as practiced in regular drills. The combination of life-safety structural performance (with a few exceptions) due in part to moderate shaking, as well as anchoring of heavy furnishings, and student preparedness and drills to practice protective action, appears to have protected students. Both districts’ experiences provide evidence that school seismic safety programs are valuable, even if efforts to mitigate risks from older, vulnerable schools are in process and more work remains.

The FEMA P-58 performance-based earthquake engineering methodology was used to assess the economic losses associated with earthquake damage to nonstructural components of two prototype buildings with post-tensioned cross-laminated timber rocking walls. A suite of 22 far-field ground motions were used for nonlinear time history (NLTH) analysis. Truncated incremental dynamic analysis was used to scale the ground motions, and results of the NLTH analyses were used to develop cumulative distribution functions for inter-story drift and peak floor accelerations. The economic factors assessed in the risk analysis included the expected repair cost with respect to spectral acceleration, the probability of exceeding an expected repair cost for selected time periods, and the expected annual loss over different time periods considering various discount factors. It was determined that the ratio of nonstructural repair cost to total building cost at the design earthquake and maximum considered earthquake was lower for the low-rise building than the mid-rise building. However, the probability of nonstructural damage at the service-level earthquake was lower for the mid-rise building than the low-rise building.

Modern reinforced concrete structures are typically designed to form plastic hinges during strong earthquakes. In post-earthquake situations, repair of moderate plastic hinging damage can be undertaken by filling the crack system with epoxy resin and reconstituting spalled cover concrete. This study uses available experimental test data, including three large-scale ductile beams tested by the authors, to investigate the effects of epoxy repair on the structural behaviour of plastic hinges, with a focus on beam elements. Factors that have been neglected in past studies, including the effects of residual deformations at the time of repair, are given special attention. It is found that epoxy-repaired plastic hinges can exhibit different behaviour from identical undamaged components in terms of stiffness, strength, deformation capacity, and axial elongation. Potential explanations for the observed differences in behaviour are given, and recommendations are made for how these differences can be quantified in order to relate the expected response of an epoxy-repaired plastic hinge to the response that would be calculated for an identical undamaged component.

Modern reinforced concrete buildings are often designed to dissipate energy during strong earthquakes by permitting the controlled formation of plastic hinges. Plastic hinges require assessment of residual capacity in post-earthquake situations. However, few past studies have investigated this topic, and results from experiments focused on undamaged structures are not always transferable to post-earthquake situations. Data from an experimental program, in which both cyclic and earthquake-type loadings were applied to nominally identical reinforced concrete beams, are used to investigate the relationship between residual crack widths and rotation demands. Assessment of the peak deformation demands incurred during a damaging earthquake is critical for post-earthquake assessments, but residual crack widths are shown to be dependent on several factors in addition to the peak rotation demand. Non-dimensional metrics capturing the distribution of cracking are proposed as a more informative alternative. The reduction in stiffness that occurs as a result of earthquake-induced plastic hinging damage was also investigated. A proposed model is shown to give a lower-bound estimate of the residual stiffness following arbitrary earthquake-type loadings.

The use of deformation capacity limits is becoming increasingly common in seismic design and assessment of reinforced concrete (RC) walls. Deformation capacity limits for RC walls in existing design and assessment documents are reviewed using a comprehensive database. It is found that the existing models are inconsistent and do not account for variation in deformation capacity with changes in the ratio of neutral axis depth to wall length ( c/ L w) and ratio of transverse reinforcement spacing to longitudinal bar diameter ( s/ d b) at the wall end region. A new mechanics-based model considering strain limits on the concrete and reinforcement is recommended. Concrete compressive strain limits for different levels of wall end region detailing are selected based on curvature ductilities for the walls in the database. Reinforcement tensile strain is limited based on a model for bar buckling. The proposed model, which accounts for c/ L w and s/ d b, is shown to have less dispersion and more accuracy than existing models when compared against experimental data and provides consistency between assessment and design provisions.

Nonlinear time history analyses were conducted for 5-story and 12-story prototype buildings that used post-tensioned cross-laminated timber rocking walls coupled with U-shaped flexural plat...

The 2010–2011 Canterbury Earthquakes in New Zealand highlighted the vulnerability of gravity load resisting reinforced concrete frames in older buildings that do not comply with modern buil...

A set of tests on 17 large-scale, nominally identical, beam specimens with variations in loading protocol, loading rate, and restraint to axial elongation are described. Three specimens were also repaired by epoxy injection following an initial damaging earthquake loading. This paper provides a detailed description of the test program, and the corresponding data are made available at Design-Safe (DOI: 10.17603/DS2SQ2K). While the primary goal of the test program was to improve the state of knowledge regarding the post-earthquake residual capacity of reinforced concrete plastic hinges in beams, the data are useful for modeling approaches that consider loading rate, plastic hinge elongation, cyclic degradation, and flexure–shear–axial interaction, in addition to investigating the effectiveness of post-earthquake repair techniques by epoxy injection of cracks.

As a result of the 2010-2011 Canterbury earthquakes, over 60% of the concrete buildings in the Christchurch Central Business District have been demolished. This experience has highlighted the need to provide guidance on the residual capacity and repairability of earthquake-damaged concrete buildings. As limited testing has been performed on repaired components, this study focuses on the performance of severely-damaged lightly-reinforced concrete walls repaired through replacement of reinforcement and concrete in the damaged region. The damage prior to repair included buckling and fracture of longitudinal reinforcement, crushing and spalling of concrete, and, for one of the two specimens, out-of-plane instability of the gross section. Prior to repairing the wall specimens, tensile testing of reinforcement with welded connections was conducted to verify acceptable performance of welds suitable for reinstating the damaged reinforcement. Repairs to the specimens consisted of removal of damaged concrete through either hydro-demolition or jack hammering, followed by cutting and removal of damaged reinforcement and reinstatement of new reinforcement and repair mortar. The two repaired wall specimens were tested using a standard protocol that was identical to that used for one of the two original wall specimens. Aside from a difference in the elastic stiffness, the load-deformation responses of the repaired specimens were similar to that of the originally-tested specimen through to the first loading cycle at 2.0% drift, beyond which strength degradation was more pronounced for the repaired specimens. The overall performance of the repaired walls relative to the original wall indicates that it is feasible to achieve acceptable performance of severely-damaged concrete walls repaired through replacement of reinforcement and concrete in the damaged region.

Experimental testing was conducted on four large-scale, flexure-yielding walls with rectangular cross sections to investigate the impact of imposed axial load ratio (10, 14, and 20% of axia...

An analytical algorithm was developed to compute the midpanel deflection history for reinforced concrete two-way floor slabs in multistory buildings. Midpanel deflection was determined usin...

Structural steel-reinforced concrete (SRC) coupling beams are an alternative to conventional and diagonal rebar-reinforced concrete coupling beams. To address gaps in previous testing that was used to develop design recommendations, four large-scale, flexure-yielding, cantilever SRC coupling beams were embedded, without inclusion of auxiliary transfer bars and bearing plates, into reinforced concrete structural walls. Beams were tested by applying quasi-static, reversed-cyclic shear loading to the coupling beam, and moment and shear to the top of the wall to create cyclic tension and compression fields across the embedment region. The primary test variables were the structural steel section embedment length, beam span length (aspect ratio), quantities of wall boundary longitudinal and transverse reinforcement, and applied wall loading (moment, shear, and axial load). Favorable performance, characterized by minimal pinching and asymmetry in the load-deformation response and concentration of damage ...

Using test results presented in previous studies, design and modeling recommendations for steel-reinforced concrete (SRC) coupling beams are provided for both code-based (prescriptive) design approaches and performance-based design approaches. Procedures for computing both nominal and expected (upper bound) moment and shear strengths are described. For embedment, a capacity design approach is recommended in which the provided embedment strength exceeds the expected beam strength. Two approaches are recommended for determination of effective stiffness, one based on using a rigid beam (for flexure and shear) along with an interface rotational spring, since test results from the literature indicate that the majority of the coupling-beam deformations were associated with interface slip/extension, and an alternative approach where the effective stiffness is based on the beam aspect ratio or beam length. Additional parameters are provided to define deformation capacity at significant strength loss (to c...

The objective of this study was to compare the shear bond strength to zirconium oxide ceramic of adhesive-phosphate-monomer-containing (APM) and non-APM-containing (nAPM) luting cements after different surface treatments. nAPM cements: Bifix QM, Dual Cement, Duo Cement Plus, Multilink Automix, ParaCem Universal DC, PermaCem Smartmix, RelyX ARC, Variolink Ultra, and Variolink II; APM cements: Panavia EX, Panavia F2.0, and RelyX UniCem. Groups of ten test specimens were each prepared by layering luting cement, using cylindrical Teflon molds, onto differently treated zirconium dioxide discs. The surface treatments were airborne-particle abrasion with 110 mum alumina particles, silica coating (SC) using 30 mum alumina particles modified by silica (Rocatec System) or SC and silanization. Bifix QM and Multilink Automix were used in combination with an additional bonding/priming agent recommended by the manufacturers. After 48 h of water storage, each specimen was subjected to a shear test. Combinations involving APM-containing cements (14.41-23.88 MPa) generally exhibited higher shear bond strength than those without APM (4.29-17.34 MPa). Exceptions were Bifix QM (14.20-25.11 MPa) and Multilink Automix (19.14-23.09 MPa) in combination with system-specific silane or priming agent, which were on the upper end of shear bond strength values. With the use of the Rocatec system, a partially significant increase in shear bond strength could be achieved in nAPM cement. Modified surface treatment modalities increased the bond strength to zirconium oxide, although the most important factor in achieving a strong bond was the selection of a suitable cement. System-specific priming or bonding agents lead to further improvement.

The aim of the study was to evaluate the influence of fatigue and cementation mode on the fracture behavior of endodontically treated bovine incisors restored with zirconium dioxide posts and crowns. Forty-eight endodontically treated bovine primary incisors were restored with zirconium dioxide posts (Cerapost, Brasseler), composite build-ups, and crowns cast from a chromium cobalt alloy. In 16 teeth, each of the posts was cemented conventionally with KetacCem (3M ESPE) or adhesively with Panavia F (Kuraray) or RelyX UniCem (3M ESPE). One-half of the specimens in each group were subjected to thermocycling with 10,000 cycles at 5-55 degrees C and mechanical aging, loading the specimens at an angle of 45 degrees in 1,200,000 cycles with 50 N. Fracture resistance was determined by loading the specimens until fracture at an angle of 45 degrees to the long axis of the teeth. The loading test showed that neither cementation mode nor fatigue testing had an influence on the load bearing capability. Most specimens fractured in a favorable way, independent from the type of cementation.

Purpose The aim of the study was to evaluate the influence of different posts on the fracture load and fracture mode of endodontically treated premolars with class II cavities and direct composite restorations in an ex vivo setting. Methods Forty-eight single-rooted human premolars were endodontically treated and prepared with standardized MO (mesio-occlusal) cavities. Eight teeth each received either no posts or were restored with titanium screws (BKS), glass fiber posts (DentinPost), or quartz fiber posts (DT Light SL). Sixteen teeth were restored with zirconium dioxide posts (CeraPost). BKS-screws and eight zirconium dioxide posts were cemented conventionally with glass ionomer cement; Panavia F resin cement was used for all others. The specimens were restored with direct composite restorations. Eight sound premolars served as the controls. After thermomechanical fatigue testing, the samples were loaded until fracture occurred at an angle of 45°. All specimens were evaluated for fracture lines. Results The sound teeth showed the significant highest fracture load (792.50 ± 210.01 N). The group restored with quartz fiber posts differed not significantly from the control. In the groups with fiber posts and titanium screws significant higher fracture load values occurred as in the group with direct composite restorations without posts. The groups with fiber posts did not show a more favorable fracture mode than the other groups. Clinical significance The use of an intraradicular post in premolars with class II cavities can significantly increase the resistance towards extra-axial forces.

A tunable modulated broadband source and narrow-bandwidth filter are used to measure chromatic dispersion, group-delay ripple, and pass-band shape of DWDM-network light paths. This new method is simple and suitable for in-service measurements.

An integrated, computerized monitoring system that provides for the capture and analysis of vibration data is described. The heart of the system is the Transient Data Manager (TDM) Communications Processor (CP), a computer interface that captures data during machine startup or coastdown. In addition, steady-state data are captured during online machine operation. Data captured include current static values and dynamic waveforms. The system collects and stores static data every four seconds from each monitor in a rack. In addition, dynamic transducer waveform data are captured and stored from each applicable monitor approximately every 40 seconds. Any time an alert, danger, or transducer-not-OK status is detected, the information is stored in an alarm event list. A status change notification is sent to the computer, and the computer subsequently retrieves the list and notifies the user of the status change. The system consists of at least one CP, software, and a computer. Examples of its application are provided. The future use of expert systems for this application is discussed. >

This study was undertaken to determine how amniotomy performed during different phases of delivery affects mother and child. 1504 out of 4770 birth recorded during one year at the University Department of Obstetrics and Gynaecology in Graz were analyzed. None of these was associated with the presence of risk factors at the onset of delivery nor when amniotomy was performed. Regardless of parity, the number of ensuing complications was clearly related to the time at which amniotomy was performed: the earlier the amnion was perforated, the higher the rate of complications, particularly with primiparae. The aim of activation of labour, thereby accelerating the process of delivery by early amniotomy, was not, however, achieved. Consequently, amniotomy should not be regarded as the method of choice for the programmed induction or the acceleration of delivery. Medication should be the first step taken towards getting delivery under way and amniotomy postponed until contractions are well established and the uterine os is at least 7 cm open in primiparae and at least 4 cm in multiparae.

In March 2020, COVID-19 infections began to rise exponentially in the United States, placing substantial burden on the healthcare system. As a result, there was a rapid change in transplant practices and policies, with cessation of most procedures. Our goal was to understand changes to pediatric kidney transplantation (KT) at the national level during the COVID-19 epidemic. Using SRTR data, we examined changes in pediatric waitlist registration, waitlist removal or inactivation, and deceased donor and living donor (DDKT/LDKT) events during the start of the disease transmission in the United States compared to the same time the previous year. We saw an initial decrease in DDKT and LDKT by 47% and 82% compared to expected events and then a continual increase, with numbers reaching expected pre-pandemic levels by May 2020. In the early phase of the pandemic, waitlist inactivation and removals due to death or deteriorating condition rose above expected values by 152% and 189%, respectively. There was a statistically significant decrease in new waitlist additions (IRR 0.49 0.65 0.85 ) and LDKT (IRR 0.17 0.38 0.84 ) in states with high vs low COVID activity. Transplant recipients during the pandemic were more likely to have received a DDKT, but had similar cPRA, waitlist time and cause of ESRD as before the pandemic. The COVID-19 pandemic initially reduced access to kidney transplantation among pediatric patients in the United States, but has not had a sustained effect.