Safety resilience is an important field in urban safety research. This paper defines the level of urban safety resilience based on a resilience curve and presents an urban safety resilience model that includes an urban structure model, urban safety resilience model, emergency model and urban recovery model. The model is used to analyze a virtual city including the architecture, traffic, power, communication and water supply sub-systems. The urban seismic safety resilience is then analyzed quantitatively using the Monte Carlo method. The model framework and method have good scalability and can provide support for constructing and assessing the safety resilient of a city.

A safety resilience analysis of Chinese earthquake emergency response characteristics was used to develop a training program to improve the abilities of professional rescuers regarding rapid disaster assessment, survivor search and rescue, action planning and emergency medical treatment. Simulations were used to analyze building damage triggering mechanisms and damage characteristics in strong earthquakes for various working conditions. The finite element simulations of common earthquake disaster scenes show the potential distribution of survivors in the field. The simulations provide theoretical support and a quantitative basis for designing training functions such as structural support training, search and rescue training, vertical transfer training, inclined staircase training, high altitude rescue training and temporary camp construction training for emergency rescue training for earthquakes.

Urban rail transit systems will have fully automatic operation (FAO) in the near future. The noise characteristics of urban rail transit stations with fully automatic operating systems were investigated at 9 elevated stations along the YF line with noise measurements on the platforms, station halls, control rooms and equipment rooms. The average L_Aeq of the train arrival and departure noise were below the standard limits of 80 dB(A). The average L_Aeq in the station halls was 68~76 dB(A) with the high noise levels due to the PA system. The average L_Aeq in the control rooms was 47~65 dB(A). The average L_Aeq in the equipment control room ranged from 47 to 61 dB(A). The measured values were used to calculate the daily noise dose received by the station staff which ranged from 69 to 72 dB(A) during the day shift and from 66 to 69 dB(A) during the night shift. The fully automatic systems have lower noise levels than manual control systems and automatic train operation systems when trains are arriving and leaving the stations.

Leakage from underground medium pressure gas pipelines can easily lead to major fires and explosions. A physical model was developed to model accidents in real underground building structures. CFD simulations were then used to predict the gas diffusion and explosion characteristics for leaks from medium pressure pipelines. The safety characteristics of the underground space were analyzed along with the impact of the accident on the resilience of the underground space. The study concluded that 2 s and 210 s are two important critical leak times for the given leakage and space characteristics. The gas concentration in a cooked food portion of a kitchen with gas leakage reached the lower explosion limit at 2 s, while the gas concentration in the hall outside the kitchen reached the lower flammability limit at 210 s. The gas explosion overpressure in the kitchen was about 12 kPa. The explosion overpressure for a 1 m thick gas layer along the top of the hallway was approximately 24 kPa. The shock wave from the kitchen explosion had little influence on the structural stability of the building, while that from the hallway explosion damaged the building structure but did not lead to complete failure of the structure. Thus, poor fire resistance in the underground space can lead to accidents and significantly impact the safety resilience. Gas explosions can affect the bearing capacity, absorption capacity and resilience of the underground space. An accident characterization curve was then developed to show the safety resilience of underground spaces with the resilience a function of the gas leakage length. The key point when the accident transitions from the formation of a dangerous condition to an explosion and deflagration is the relative location of the ignition source. More serious accidents have longer recovery times and higher costs but with better designs after the accident. The key measures to improve the spatial resilience are to promptly close the leakage source, improve ventilation to avoid the formation of a flammable cloud, control ignition sources, increase pressure relief areas, and improve space fire performance.

Crowd evacuation simulations were used to evaluate evacuation capabilities and disaster response strategies for mountainous neighborhoods. The results were used to develop evacuation plans based on the building layout, road networks, exit distribution and greenery morphology. The simulations used an agent based model for the crowd evacuation simulations with control groups based on potential paths, spatial enclosure degree and green space layout. The simulations give the overall evacuation time, best paths, congestion characteristics and changes in the number of people in various sections. The results also show how the structure affects the crowd evacuation behavior and the overall safety to support mountainous neighborhood safety evacuation planning and disaster response planning in southwest China.

One key technical problem of the Hong Kong-Zhuhai-Macao Bridge is the structural response to high winds. This study included wind tunnel tests of a conventional sectional model, a large sectional model, a full-bridge aeroelastic model and a self-supporting aeroelastic tower model for three channel bridges and non-navigable bridges. The results indicate that the original design of the Hong Kong-Zhuhai-Macao Bridge may suffer from wind effects such as flutter, unacceptable vortex-induced vibrations and tower galloping. Aerodynamic and structural modifications are given to eliminate the wind problems of the Hong Kong-Zhuhai-Macao Bridge. This research provides guidance for guaranteeing the safety of the Kong-Zhuhai-Macao Bridge in high winds.

This paper describes a high-toughness, ultra-thin friction course developed to improve the pavement quality and extend the service life of the channel (originally a temporary bridge) for the artificial island in the Hong Kong-Zhuhai-Macao Bridge. The effects of extra loads and the extended operating period on the bridge were investigated experimentally for various binding materials, gradation designs, repair plans for the bridge deck, various bonding interface treatment, and construction quality management techniques. The results show that the high-toughness, ultra-thin friction course coupled with synchronous paving provides thinner pavement thicknesses, much higher mechanical strength, less compaction requirement, and higher construction efficiency. The texture depth (increased by 0.34 mm), friction coefficient (increased by 15.5 BPN), noise (reduced by 3~6 dB), and flatness (improved from 6.5 mm to 1.4 mm) were significantly better than for the original cement concrete bridge pavement. The water sealing ability (< 30 mL/min) and the debonding strength (> 0.7 MPa) reached a good condition. This paving system can also be applied upgrade highway, urban road, bridge, and tunnel surfaces.

Steel box girder with large projecting slab applied in Hong Kong-Zhuhai-Macao Bridge (HZMB), is very prone to vortex-induced vibration (VIV) due to its bluff configuration. A series of section models and full aeroelastic bridge models wind tunnel tests were conducted to investigate the effects of aerodynamic measures and additional damping measures for mitigating the VIV of HZMB. The results show that two vertical VIV regions and one torsional VIV region were observed during the wind tunnel tests. According to the VIV amplitude and wind speed range of each case, the particular attention should be paid on the second vertical VIV region for the cable-stayed bridges of navigable span and the first vertical VIV region for the continuous beam bridges of non-navigable span. The VIV performance of the bridges was efficiently improved by installing arc-shaped guide vane on guardrails. In addition, the VIV amplitude were reduced significantly by increasing additional damping, and the VIV phenomenon disappeared when the damping ratio increases to 1.0%, which can be used for the design of the tuned mass damper (TMD) for HZMB. Finally, the consistency of wind tunnel test results between section model and full bridge aeroelastic model was discussed by three-dimensional nonlinear VIV analysis method.

Based on the analysis of wind-tearing the vertical locked side metal roof of the Travel Inspection Building on Zhuhai Port of Hong Kong-Zhuhai-Macao Bridge and other similar projects, as well as the dynamic and static tests of wind-tearing metal roof, this paper analyses the increase of equivalent basic wind pressure in recent years, and suggests that the basic wind pressure should be adjusted appropriately according to the change of extreme weather. It is pointed out that in typhoon-prone regions such as Guangdong, Hong Kong and Macao, the 8-10 s fluctuation period can more truly reflect the typhoon environment in the region. The test also reveals that the control wind force of metal roof tore by wind is dynamic pulsing wind. Because the joint of the roof panel rib and T code bearing is easy to be detached, it is suggested that the wind-resistant clamps should be generally installed in this part, the purlin spacing should be closed, wind-resistant clamp spacing should be closed, and wind-resistant depression bars should be installed in weak parts such as eaves etc. It is suggested that the strength and stiffness of the metal roof slab, T code bearing, tapping screw and wind clamp should be specified in the code or design. It is suggested that the metal roof should be divided into warehouse joints at a certain distance to avoid the domino effect when the metal roof is tore by wind.

Structural imperfections in ring micro-electromechanical system (MEMS) gyroscopes lead to frequency splitting of the operating mode and axial deflection of the vibrations, which are some of the main factors affecting the performance. The mass distribution imperfections most strongly influence the fourth harmonic component. The angular position of this defect is determined from the frequency response characteristics at the detection electrodes of the ring structure which were analyzed theoretically in this study for various defect angles. A method is also given to calculate the intrinsic axial direction of the ring structure operating mode from the frequency response parameters. The accuracy of this method was verified against finite element calculations of the harmonic response of the ring structure with structural defects with the results showing that the intrinsic axial relative error is about 2%.

Micro inertial measurement units (MIMU) based on micro-electro-mechanical-system (MEMS) designs are very small and light with low power consumption, but they have large inertial errors that limit applications. The rotation modulation technique was used to reduce the influence of these errors so that the MIMU systems can more accurately identify the northern direction. However, there have been few observability analyses of MIMU devices with the observability closely related to whether the Kalman filtering can accurately estimate the error state. This study analyzes the MIMU observability using Kalman filtering based on measured data for stationary, multi-position and continuous rotation conditions. The results show that the heading angle error in the stationary condition is quite large and the device cannot be self-aligned. A multi-positioning scheme with rotation around the heading axis and the pitch axis makes the MIMU error state completely observable. With continuous rotation, the Kalman filtering can quickly estimate the heading angle and the azimuth accelerometer bias with the azimuth gyro drift estimated after a short period of time. The gyro drift and the accelerometer bias in the horizontal plane cannot be accurately estimated using Kalman filtering, but they can be measured by the north-seeking algorithm. The research provides a theoretical basis for improving the self-alignment accuracy of MIMU devices and evaluating their performance.

Numerical simulations were used to study the effect of welding sequence and surfacing thickness on the residual stresses and deformation after on-line surfacing welding repair of the flange surface of a nuclear grade pipe. The simulations show that the welding sequence from the inside to the outside wall leads to smaller residual stresses and deformation due to the different thicknesses of the inside and outside walls of the flange and the rigidity differences between the connecting pipes. With a 20 mm surfacing thickness, the residual axial stress at the welding seam of the outer pipe wall is close to the material yield strength. With surfacing thicknesses no more than 15 mm thick, the residual stress at the welding seam of the outer pipe wall is far lower than the yield strength. A sample specimen was made using the optimized welding process with the residual stress then measured using X-ray diffraction. The predicted stresses agree well with the measured data to verify the simulation results.

Existing fire-spreading models for building clusters mostly consider 2-D horizontal spreading without the influence of ground elevation, so they are not accurate for building clusters with large elevation changes. A 3-D fire-spreading model was developed here for building clusters with different ground elevations. Existing 2-D models were extended to 3-D models for the thermal radiation and plumes in a 3D fire-spreading model for building clusters. The 3-D fire spreading model was then verified against computational fluid dynamics (CFD) models. The model was then used to model the spreading of fires in Dukezong, Yunnan and Hot Spring Village, Guizhou as examples that have large elevation changes with the 3-D spreading results being more accurate than 2-D spreading results. Thus, this work provides a more accurate simulation method for fire spreading for building clusters in mountainous or hilly areas where the elevations change significantly.