Intelligent Risk-Identification Algorithm with Vision and 3D LiDAR Patterns at Damaged Buildings

Existingfirefighting robots are focused on simple storage orfire sup-pression outside buildings rather than detection or recognition.Utilizing a large number of robots using expensive equipment is challenging.This study aims to increase the efficiency of search and rescue operations and the safety offirefigh-ters by detecting and identifying the disaster site by recognizing collapsed areas,obstacles,and rescuers on-site.A fusion algorithm combining a camera and three-dimension light detection and ranging(3D LiDAR)is proposed to detect and loca-lize the interiors of disaster sites.The algorithm detects obstacles by analyzingfloor segmentation and edge patterns using a mask regional convolutional neural network(mask R-CNN)features model based on the visual data collected from a parallelly connected camera and 3D LiDAR.People as objects are detected using you only look once version 4(YOLOv4)in the image data to localize persons requiring rescue.The point cloud data based on 3D LiDAR cluster the objects using the density-based spatial clustering of applications with noise(DBSCAN)clustering algorithm and estimate the distance to the actual object using the center point of the clustering result.The proposed artificial intelligence(AI)algorithm was verified based on individual sensors using a sensor-mounted robot in an actual building to detectfloor surfaces,atypical obstacles,and persons requiring rescue.Accordingly,the fused AI algorithm was comparatively verified.

Damage characteristics and seismic capacity of buildings during Nepal M_s 8.1 earthquake

The extensive damage to buildings caused by the Nepal Ms8.1 earthquake has attracted much attention by the international community.Afterthe preliminary scientific investigations on the different affected areas inNepal,the construction and damage characteristics of five different types of buildings commonly existing in Nepal were discussed and the reasons of their disaster performance were analyzed.Types of buildings investigated include reinforced concrete(RC) frame structures,rubble structures,brick-wood structures,raw soil structures,and brick-wood structures of historic buildings.In addition,the weak links of the seismic design were pointed out,which was very important for the post-earthquake reconstruction and recovery,and gave a preliminary explanations for the damage experienced.

Damage to urban buildings in zones of intensities Ⅷ and Ⅶ during the Wenchuan earthquake and discussion on some typical damages

The outline and typical characteristics of damages to building in Jiangyou city and Anxian county （intensity Ⅷ）, Mianyang city and Deyang city （intensity Ⅶ） are introduced in the paper. The damage ratios, based on the sample statistics of multi-story brick buildings together with multi-story brick buildings with RC frame at first story （BBF）, are presented. Then some typical damages, such as horizontal cricks of brick masonry buildings, X-shaped cricks on the walls under windows, the damages to columns, beams and infill walls of frame buildings and the damage to half circle-shaped masonry walls, are discussed.

Vision-based Recognition Algorithm for Up-To-Date Indoor Digital Map Generations at Damaged Buildings

When firefighters are engaged in search and rescue missions inside a building at a risk of collapse,they have difficulty in field command and rescue because they can only simplymonitor the situation inside the building utilizing old building drawings or robots.To propose an efficient solution for fast search and rescue work of firefighters,this study investigates the generation of up-to-date digital maps for disaster sites by tracking the collapse situation,and identifying the information of obstacles which are risk factors,using an artificial intelligence algorithm based on low-cost robots.Our research separates the floor by using the mask regional convolutional neural network(R-CNN)algorithm,and determines whether the passage is collapsed or not.Then,in the case of a passage that can be searched,the floor pattern of the obstacles that exist on the floor that has not collapsed is analyzed,and obstacles are searched utilizing an image processing algorithm.Here,we can detect various unknown as well as known obstacles.Furthermore,the locations of obstacles can be estimated using the pixel values up to the bounding box of an existing detected obstacle.We conduct experiments using the public datasets collected by Carnegie Mellon university(CMU)and data collected by manipulating a low-cost robot equipped with a smartphone while roaming five buildings in a campus.The collected data have various floor patterns for objectivity and obstacles that are different from one another.Based on these data,the algorithm for detecting unknown obstacles of a verified study and estimating their sizes had an accuracy of 93%,and the algorithm for estimating the distance to obstacles had an error rate of 0.133.Through this process,we tracked collapsed passages and composed up-to-date digital maps for disaster sites that include the information of obstacles that interfere with the search and rescue work.

Characteristics of Seismic Damage of Buildings:Constraints from Tilt Photography Technology

In this paper,the tilt photography data acquisition and three-dimensional modeling of the Tashkurgan MS5.5 earthquake in Xinjiang are conducted using the tilt photography system of the Rotor UAV. The three-dimensional model is used to interpret the earthquake damage on buildings in the mega-earthquake area in order to acquire different-level house damage in the Kuzirun village disaster area. In addition,the characteristics of seismic damage on typical buildings are analyzed. The results show that the main collapsed houses in the mega-earthquake area are sand-stone buildings,of which about 39% are sand-stone buildings. Several brick-wood buildings and brick-concrete buildings are seriously damaged,while the buildings with frame structures are mainly slightly damaged,and the houses near the macro-epicenter of the earthquake are all in good conditions. Three-dimensional tilt photography technology can vividly display the scene of earthquake disaster,and can provide significant demonstration in building damage degree together with detailed analysis of disaster situation.

Building damage in Dujiangyan during Wenchuan Earthquake

A field damage survey of 1,005 buildings damaged by the Wenchuan Earthquake in Dujiangyan City was carried out and the resulting data was analyzed using the statistical method. It is shown that buildings that were seismically designed achieved the desired seismic fortification target; they sustained less damage than the non-seismically designed buildings. Among the seismically designed buildings investigated, RC frame buildings performed the best in terms of seismic resistance. Masonry buildings with a ground story of RC frame structure were the second best, and masonry buildings performed the worst. Considering building height, multistory buildings sustained more severe damage than high-rise buildings and 2- and 3-story buildings. Compared to residential buildings, public buildings, such as schools and hospitals, suffered more severe damage.

Performance-based methodology for assessing seismic vulnerability and capacity of buildings

This paper presents a performance-based methodology for the assessment of seismic vulnerability and capacity of buildings. The vulnerability assessment methodology is based on the HAZUS methodology and the improved capacity- demand-diagram method. The spectral displacement (Sd) of performance points on a capacity curve is used to estimate the damage level of a building. The relationship between Sd and peak ground acceleration (PGA) is established, and then a new vulnerability function is expressed in terms of PGA. Furthermore, the expected value of the seismic capacity index (SCev) is provided to estimate the seismic capacity of buildings based on the probability distribution of damage levels and the corresponding seismic capacity index. The results indicate that the proposed vulnerability methodology is able to assess seismic damage of a large number of building stock directly and quickly following an earthquake. The SCev provides an effective index to measure the seismic capacity of buildings and illustrate the relationship between the seismic capacity of buildings and seismic action. The estimated result is compared with damage surveys of the cities of Dujiangyan and Jiangyou in the M8.0 Wenchuan earthquake, revealing that the methodology is acceptable for seismic risk assessment and decision making. The primary reasons for discrepancies between the estimated results and the damage surveys are discussed.

Seismic fragility assessment of RC frame structure designed according to modern Chinese code for seismic design of buildings

Following several damaging earthquakes in China, research has been devoted to find the causes of the collapse of reinforced concrete （RC） building sand studying the vulnerability of existing buildings. The Chinese Code for Seismic Design of Buildings （CCSDB） has evolved over time, however, there is still reported earthquake induced damage of newly designed RC buildings. Thus, to investigate modern Chinese seismic design code, three low-, mid- and high-rise RC frames were designed according to the 2010 CCSDB and the corresponding vulnerability curves were derived by computing a probabilistic seismic demand model （PSDM）.The PSDM was computed by carrying out nonlinear time history analysis using thirty ground motions obtained from the Pacific Earthquake Engineering Research Center. Finally, the PSDM was used to generate fragility curves for immediate occupancy, significant damage, and collapse prevention damage levels. Results of the vulnerability assessment indicate that the seismic demands on the three different frames designed according to the 2010 CCSDB meet the seismic requirements and are almost in the same safety level.

Building Damage Extraction from Post-earthquake Airborne LiDAR Data

Building collapse is a significant cause of earthquake-related casualties; therefore, the rapid assessment of buildings damage is important for emergency management and rescue. Airborne light detection and ranging （LiDAR） can acquire point cloud data in combination with height values, which in turn provides detailed information on building damage. However, the most previous approaches have used optical images and LiDAR data, or pre- and post-earthquake LiDAR data, to derive building damage information. This study applied surface normal algorithms to extract the degree of building damage. In this method, the angle between the surface normal and zenith （0） is used to identify damaged parts of a building, while the ratio of the standard deviation to the mean absolute deviation （σ/δ） of θ is used to obtain the degree of building damage. Quantitative analysis of 85 individual buildings with different roof types （i.e., flat top or pitched roofs） was conducted, and the results confirm that post-earthquake single LiDAR data are not affected by roof shape. Furthermore, the results confirm that θ is correlated to building damage, and that σ/δ represents an effective index to identify the degree of building damage.

Building damages in Deyang city by the 2008 Wenchuan earthquake

The Ms8.0 Wenchuan earthquake in 2008 caused huge casualties, economic losses, and building damages , which are analyzed. The results show that damages of houses designed according to the current seismic code were significantly smaller than those without such design, suggesting that the code has achieved the desired goal of seismic fortification. Buildings of different kinds of structures showed large differences in damages ： Houses with steel-frames and shear walls or steel structures suffered the least damages ; those with frames or with brick-and-concrete structures suffered more; old cottages, the most.

Revision of seismic design codes corresponding to building damagesin the “5.12” Wenchuan earthquake

A large number of buildings were seriously damaged or collapsed in the "5.12" Wenchuan earthquake. Based on field surveys and studies of damage to different types of buildings, seismic design codes have been updated. This paper briefly summarizes some of the major revisions that have been incorporated into the "Standard for classification of seismic protection of building constructions GB50223-2008" and "Code for Seismic Design of Buildings GB50011-2001." The definition of seismic fortification class for buildings has been revisited, and as a result, the seismic classifications for schools, hospitals and other buildings that hold large populations such as evacuation shelters and information centers have been upgraded in the GB50223-2008 Code. The main aspects of the revised GB50011-2001 code include: (a) modification of the seismic intensity specified for the Provinces of Sichuan, Shanxi and Gansu; (b) basic conceptual design for retaining walls and building foundations in mountainous areas; (c) regularity of building configuration; (d) integration of masonry structures and precast RC floors; (e) requirements for calculating and detailing stair shafts; and (f) limiting the use of single-bay RC frame structures. Some significant examples of damage in the epicenter areas are provided as a reference in the discussion on the consequences of collapse, the importance of duplicate structural systems, and the integration of RC and masonry structures.

Availability of seismic vulnerability index(K_g) in the assessment of building damage in Van, Eastern Turkey

The seismic vulnerability index(Kg) is a parameter that depends on the dynamic properties of soil. With this parameter, it is possible to evaluate the vulnerability of a point-based site under strong ground motion. Since it is related to the natural vibration period and amplification factor, the parameter can be calculated for both soil and structure. In this study, HVSR microtremor measurements are recorded at more than 200 points in the Van region to generate a seismic vulnerability index map. After generating the map, it is determined that the hazard potential and seismic vulnerability index is high at the sites close to Van Lake and at the densely populated city center. Damage information of the buildings investigated after the 2011 Van earthquakes(Mw = 7.1) are placed on the seismic vulnerability index map and it is realized that there may be a correlation between the damage and the seismic vulnerability index. There is a high correlation, approximately 80 percent, between the damage rate map based on the damaged building data and the K_g values. In addition, vulnerability indexes of buildings are calculated and the effect of local soil conditions and building properties on the damage levels are determined. From the results of this study and the site observations after the 2011 Van earthquakes, it is found that structural damage is not only structure-dependent but is also related to the dynamic behavior of soil layers and local soil conditions.

Lessons learned from the “5.12” Wenchuan Earthquake:evaluation of earthquake performance objectives and the importance of seismic conceptual design principles

Many different types of buildings were severely damaged or collapsed during the May 12, 2008 Great Wenchuan Earthquake. Based on survey data collected in regions that were subjected to moderate to severe earthquake intensities, a comparison between the observed building damage, and the three earthquake performance objectives and seismic conceptual design principles specified by the national ＂Code for Seismic Design of Buildings GB50011-2001,＂ was carried out. Actual damage and predicted damage for a given earthquake level for different types of structures is compared. Discussions on seismic conceptual design principles, with respect to multiple defense lines, strong column-weak beam, link beam of shear walls, ductility detailing of masonry structures, exits and staircases, and nonstructural elements, etc. are carried out. Suggestions for improving the seismic design of structures are also proposed. It is concluded that the seismic performance objectives for three earthquake levels, i.e., ＂no failure under minor earthquake level, ＂＂repairable damage under moderate earthquake level＂ and ＂no collapse under major earthquake level＂ can be achieved if seismic design principles are carried out by strictly following the code requirements and ensuring construction quality.

A Deep Learning Application for Building Damage Assessment Using Ultra-High-Resolution Remote Sensing Imagery in Turkey Earthquake

Rapid building damage assessment following an earthquake is important for humanitarian relief and disaster emergency responses.In February 2023,two magnitude-7.8 earthquakes struck Turkey in quick succession,impacting over 30 major cities across nearly 300 km.A quick and comprehensive understanding of the distribution of building damage is essential for e fficiently deploying rescue forces during critical rescue periods.This article presents the training of a two-stage convolutional neural network called BDANet that integrated image features captured before and after the disaster to evaluate the extent of building damage in Islahiye.Based on high-resolution remote sensing data from WorldView2,BDANet used predisaster imagery to extract building outlines;the image features before and after the disaster were then combined to conduct building damage assessment.We optimized these results to improve the accuracy of building edges and analyzed the damage to each building,and used population distribution information to estimate the population count and urgency of rescue at different disaster levels.The results indicate that the building area in the Islahiye region was 156.92 ha,with an affected area of 26.60 ha.Severely damaged buildings accounted for 15.67%of the total building area in the affected areas.WorldPop population distribution data indicated approximately 253,297,and 1,246 people in the collapsed,severely damaged,and lightly damaged areas,respectively.Accuracy verification showed that the BDANet model exhibited good performance in handling high-resolution images and can be used to directly assess building damage and provide rapid information for rescue operations in future disasters using model weights.

Evaluation of effectiveness of three fuzzy systems and three texture extraction methods for building damage detection from post-event LiDAR data

Building damage maps after disasters can help us to better manage the rescue operations.Researchers have used Light Detection and Ranging(LiDAR)data for extracting the building damage maps.For producing building damage maps from LiDAR data in a rapid manner,it is necessary to understand the effectiveness of features and classifiers.However,there is no comprehensive study on the performance of features and classifiers in identifying damaged areas.In this study,the effectiveness of three texture extraction methods and three fuzzy systems for producing the building damage maps was investigated.In the proposed method,at first,a pre-processing stage was utilized to apply essential processes on post-event LiDAR data.Second,textural features were extracted from the pre-processed LiDAR data.Third,fuzzy inference systems were generated to make a relation between the extracted textural features of buildings and their damage extents.The proposed method was tested across three areas over the 2010 Haiti earthquake.Three building damage maps with overall accuracies of 75.0%,78.1%and 61.4%were achieved.Based on outcomes,the fuzzy inference systems were stronger than random forest,bagging,boosting and support vector machine classifiers for detecting damaged buildings.

A Low-Cost Mobile Mapping System (LCMMS) for field data acquisition: a potential use to validate aerial/satellite building damage assessment

Among the major natural disasters that occurred in 2010,the Haiti earthquake was a real turning point concerning the availability,dissemination and licensing of a huge quantity of geospatial data.In a few days several map products based on the analysis of remotely sensed data-sets were delivered to users.This demonstrated the need for reliable methods to validate the increasing variety of open source data and remote sensing-derived products for crisis management,with the aim to correctly spatially reference and interconnect these data with other global digital archives.As far as building damage assessment is concerned,the need for accurate field data to overcome the limitations of both vertical and oblique view satellite and aerial images was evident.To cope with the aforementioned need,a newly developed Low-Cost Mobile Mapping System(LCMMS)was deployed in Port-au-Prince(Haiti)and tested during a five-day survey in FebruaryMarch 2010.The system allows for acquisition of movies and single georeferenced frames by means of a transportable device easily installable(or adaptable)to every type of vehicle.It is composed of four webcams with a total field of view of about 180 degrees and one Global Positioning System(GPS)receiver,with the main aim to rapidly cover large areas for effective usage in emergency situations.The main technical features of the LCMMS,the operational use in the field(and related issues)and a potential approach to be adopted for the validation of satellite/aerial building damage assessments are thoroughly described in the article.

Grouting-induced ground heave and building damage in tunnel construction:A case study of Shenzhen metro

This paper presents a case study of the grouting-induced ground heave and building damage in the tunnel construction of Shenzhen Metro Line 10,which passes through a crowded urban area with water-rich strata in Shenzhen,the province of Guangdong,China.It was reported that the ground surface heave of up to approximately 500 mm was observed,and the customs building above the tunnels was seriously damaged because of a 200 mm heave.Such a significant heave was closely associated with the advanced curtain grouting adopted in the tunnel construction.To this end,the heave of the ground surface and the displacement and deformation of the customs building were examined.The discrete element method(DEM)was then used to qualitatively analyze the relations between the grouting parameters and the ground disturbance.The results demonstrated that the poor dewatering work in the early stages increased the difficulty of grouting.The grouting materials with high viscosity and large grouting pressure were required for water blocking because of the large amount of confined water in the tunnel,resulting in fracture grouting.The ground was then uplifted due to the large inflow of the slurry and the excess pore water pressure.Finally,the lessons learned from this incident were discussed.The presented case study provides a reference for tunnel construction in urban areas with water-rich strata.

Life-Cycle and Seismic Fragility Assessment of Code-Conforming Reinforced Concrete and Steel Structures in Bucharest, Romania

In this article, the fragility of reinforced concrete and steel structures in Bucharest, a city of high seismic hazard, designed using the recent building codes in Romania, is assessed. A total of 24 reinforced concrete and steel structures with heights varying from five stories to 13 stories were analyzed. Their seismic fragility was evaluated using two procedures from the literature. In the first procedure(SPO2 FRAG), the fragility was derived based on the pushover curves using the SPO2 IDA algorithm, while in the second procedure(FRACAS), the fragility was derived from nonlinear time-history analyses. The analyzed structures were designed for three levels of peak ground accelerations, corresponding to mean return periods of 100,225, and 475 years. Subsequently, the damage assessment of the analyzed structures was performed using ground motions generated from a Monte-Carlo simulated earthquake catalogue for the Vrancea intermediate-depth seismic source. The damage degrees that were estimated using the SPO2 FRAG approach are higher than those estimated using the FRACAS approach. The life-cycle analysis of the structures shows that a further increase of the design peak ground acceleration for Bucharest is feasible from an economic point of view using the SPO2 FRAG results.However, based on the FRACAS results, the opposite conclusion can be drawn. Finally, generic lognormal fragility functions are proposed as a function of building height and structural system.