Protect Life Safety Research Articles

Disaster Journalism Guide: "Protecting Life Safety and Human Dignity is Essential"

Disaster Journalism Guide: "Protecting Life Safety and Human Dignity is Essential"

Information Model Construction and State Analysis Strategy for Vital Signs of Power Network Inspector

Based on the requirement for protecting life safety of electric workers, the vital signs information model which consists of real time vital signs model, fatigue degree evaluation model and vital signs trends model is designed and implemented. The model is based on data collected, including basic attributes, heart rate, body temperature, blood pressure and Work scenarios. Besides, the most suitable vital signs historical data for each power maintenance personnel is calculated by the national standard and personal historical data. The model not only enhances the supervisory means of the guardians, but also greatly improves the production efficiency of the inspectors on the electric power field.

A statistical analysis of occurrence and association between structural fire hazards in heritage housing

Reported in this paper is a novel application of statistical analysis of structural fire hazards that were found in heritage housing stock in a metropolitan area. The structural fire hazards in terms of non-compliances to the building regulations are digitised and then subjected to statistical analysis to obtain estimates of probabilities of occurrence under various conditions. The concepts of Hamming distance, Jaccard distance, virtual distance and pairwise Phi correlation coefficients are employed in the analysis to estimate the association between the fire hazards. Estimates of the probability distribution over the number of joint occurrence of hazards and pairwise joint probabilities are also obtained. In addition the 3-tuple and 4-tuple joint probabilities are analysed. Finally, logistic regression models are established to correlate each fire hazard with the others. The results show that not only the probability of occurrence of structural fire hazards is high, but probability of multiple occurrence is also significant. There are indications that some structural fire hazards are correlated. The findings of this study may assist certifying authorities, building surveyors, fire safety engineers and fire services in identifying fire hazards in heritage buildings and developing alleviating and effective strategies or solutions to protect life safety of building occupants as well as the cultural heritage values of the relevant building stock.

Using failure analysis tools to establish seismic resilience objectives for building components and systems

While modern building codes have proven effective at reducing casualties caused by structural collapse following several recent earthquakes, they have been less effective at preventing damage that can lead to loss of functionality, especially in ordinary buildings (e.g., offices, factories, hotels, etc.). Because the performance of these buildings can significantly impact community recovery and resilience, it is imperative that building codes expand their current focus on protecting life safety in rare earthquakes to include provisions and requirements that aim to prevent damage and minimize loss of functionality in more frequent events. Towards this end, this paper presents a conceptual framework that directly connects performance targets for structural and nonstructural components to global resilience objectives for an entire building. The framework uses fault trees, a common failure analysis tool, to: (1) model how damage to or failure of different components and systems within a building can affect overall building functionality, and (2) provide the quantitative underpinnings for deriving consistent performance targets for building components and systems. The paper then presents a demonstration of the proposed framework to study loss of functionality in a generic commercial building and derive a set of consistent performance targets for its structural and nonstructural components. Lastly, the paper discusses potential applications of the proposed framework, including providing risk-consistent foundations for future generations of building codes and engineering standards.

Geotechnical Mitigation Strategies for Earthquake Surface Fault Rupture

AbstractSurface fault rupture can be damaging to structures built on or near active faults if the hazard is not addressed properly. Fault-induced angular distortion and lateral ground strain can cause beams to yield and eventually lead to structural collapse. When avoidance is not possible, geotechnical mitigation strategies can be used. These strategies include spreading fault displacement over a large area, causing the structure to respond with rigid-body movement, and diverting the fault rupture around the structure. The effectiveness of these strategies can vary from protecting life safety to preventing significant damage and can be effective for a range of dip-slip fault displacements. Earth fills should be sufficiently thick and ductile to prevent the underlying fault dislocation from developing at the ground surface. Thick RC mat foundations proved to be especially effective in shielding the superstructure from the damaging effects of the underlying ground movements. Although more challenging to im...

New Nonlinear Roof Sheathing Fastener Model for Use in Finite-Element Wind Load Applications

Performance-based design is being developed and implemented in seismic and fire resistant design. The field of structural wind engineering has introduced several techniques that may eventually lead to performance-based wind engineering for buildings such as database assisted design. For wood-frame buildings, one deficiency is the lack of accurate load/response models with the ability to go beyond first failure leaving only force-based approaches which protect life safety but only infer certain levels of performance. This paper introduces a new nonlinear roof sheathing fastener model that is a function of not only the uplift pressure acting on the roof sheathing, but the effective moment arm (not just the moment) acting on the edge nails. A targeted set of experimental tests was conducted to determine the effect of the load eccentricity, a new stiffness matrix for a nail element formulated, and illustrative examples presented for a roof sheathing assembly analyzed using the finite element procedure. The model is shown to result in a significantly reduced capacity from current state-of-the-art finite element analyses which assume only nail withdrawal. It is anticipated that this more accurate nail model can aid in the development of performance-based wind engineering for wood-frame buildings.

Incorporating modeling uncertainties in the assessment of seismic collapse risk of buildings

The primary goal of seismic provisions in building codes is to protect life safety through the prevention of structural collapse. To evaluate the extent to which current and past building code provisions meet this objective, the authors have conducted detailed assessments of collapse risk of reinforced-concrete moment frame buildings, including both ‘ductile’ frames that conform to current building code requirements, and ‘non-ductile’ frames that are designed according to out-dated (pre-1975) building codes. Many aspects of the assessment process can have a significant impact on the evaluated collapse performance; this study focuses on methods of representing modeling parameter uncertainties in the collapse assessment process. Uncertainties in structural component strength, stiffness, deformation capacity, and cyclic deterioration are considered for non-ductile and ductile frame structures of varying heights. To practically incorporate these uncertainties in the face of the computationally intensive nonlinear response analyses needed to simulate collapse, the modeling uncertainties are assessed through a response surface, which describes the median collapse capacity as a function of the model random variables. The response surface is then used in conjunction with Monte Carlo methods to quantify the effect of these modeling uncertainties on the calculated collapse fragilities. Comparisons of the response surface based approach and a simpler approach, namely the first-order second-moment (FOSM) method, indicate that FOSM can lead to inaccurate results in some cases, particularly when the modeling uncertainties cause a shift in the prediction of the median collapse point. An alternate simplified procedure is proposed that combines aspects of the response surface and FOSM methods, providing an efficient yet accurate technique to characterize model uncertainties, accounting for the shift in median response. The methodology for incorporating uncertainties is presented here with emphasis on the collapse limit state, but is also appropriate for examining the effects of modeling uncertainties on other structural limit states.

Using traditional and innovative approaches in the seismic evaluation and strengthening of a historic unreinforced masonry synagogue

A monumental 100-year-old multi-story brick masonry synagogue in San Francisco was threatened with closure due to non-compliance with an Unreinforced Masonry Building Ordinance. The Ordinance required demonstrating that the building would protect life safety in the event of a major earthquake or upgrading the building to do so, despite the historical record showing that the building survived the Great 1906 Earthquake with relatively little damage. Much of the minor damage that did occur is still visible today as the historic finishes have remained intact since that earthquake. The structure consists primarily of thick, brick masonry perimeter walls, wood-framed diaphragms with diagonal and straight sheathing, and riveted structural steel trusses and columns that support the dome over the main sanctuary and a large portion of the floors and main roof. The structure was subjected to linear dynamic and non-linear static analyses to benchmark its behavior during the 1906 earthquake, to better understand its vulnerabilities in the event of potentially stronger shaking, and to develop seismic improvements that minimize disturbance of its ornately detailed stone and painted plaster finishes. The most appropriate structural solution consistent with preserving the historic fabric takes advantage of the dynamic separation between the modes predominated by in-plane and out-of-plane wall shaking. The out-of-plane wall modes have long periods and low modal mass participation. The in-plane wall modes have higher mass participation, but act rigidly with little amplification. The solution consisted of a combination of intervention techniques, each developed to minimize disturbance to the non-structural finishes and retain the original dynamic characteristics. These interventions include a system of tension ties in the attic that interconnect the four perimeter walls, yet circumvent the domed sanctuary; center-cored reinforcement of the masonry walls; and fiber-wrap of a few critical piers. The tension ties contain super-elastic nitinol wires and were designed to be lightweight, easy to install, and to restrain the walls from falling outward while maintaining the modal separation and inherent flexibility of the system that enabled the structure to survive the 1906 earthquake.