A GIS-based method for spatial risk assessment of urban building seismic damage

Abstract

The present invention discloses a method for spatially evaluating the seismic damage risk of urban buildings based on GIS, which relates to the technical field of spatial seismic damage risk assessment. The method for spatially evaluating the seismic damage risk of urban buildings based on GIS provided by the present invention includes obtaining building, seismic risk data and site condition data within a region, constructing a three-dimensional model of the buildings, and integrating a seismic disaster database; constructing a seismic damage scenario simulation model to generate a heat map of the maximum displacement of the buildings; obtaining the generation probability and trajectory of secondary falling objects of the buildings based on building characteristics and ground motion parameters, and generating a heat map of the falling object risk; and obtaining the seismic damage risk of spatial units according to the heat map of the maximum displacement of the buildings and the heat map of the falling object risk, and performing visualization. Therefore, by adopting the above method, it provides a basis for risk control for disaster prevention and mitigation planning, and provides decision-making support for aspects such as building reinforcement, delineation of evacuation areas, and planning of emergency evacuation routes.

Description

Technical Field

[0001] The present invention relates to the technical field of seismic disaster spatial risk assessment, and in particular to a method for assessing the spatial risk of urban building seismic disasters based on GIS. Background Art

[0002] Buildings are the main components of a city and important disaster-bearing bodies in urban earthquake disasters. Quickly and accurately predicting the spatial safety of buildings after an earthquake is an important basis for emergency evacuation space planning and emergency rescue operations. Therefore, it is particularly important and urgent to carry out research on earthquake disaster assessment models and methods.

[0003] At present, earthquake disaster assessment models and methods mainly conduct disaster analysis on individual buildings, mainly including the vulnerability matrix method, parameter mapping method, capacity spectrum method, and pushover analysis (PUSHOVER ANALYSIS, THA) method. The vulnerability matrix method uses a matrix to represent the damage probability of buildings under different earthquake intensities; among them, the elements of the matrix are determined based on historical data, empirical models, or expert judgments. Each row of the matrix represents different earthquake intensity levels, and each column represents different degrees of building damage (from no damage to complete collapse). The parameter mapping method maps the characteristics of buildings (such as structural type, material, design, construction quality, etc.) to one or more parameters, and uses these parameters to estimate the vulnerability of buildings, usually used for quickly evaluating the seismic performance of a large number of buildings. The capacity spectrum method (CSM) estimates the damage probability by comparing the seismic capacity (demand) of a building with the effects or actions caused by an earthquake; among them, the capacity curve shows the response of the building structure under different earthquake effects, and the demand curve represents the force that the earthquake may exert. The intersection point of the two is used to estimate the response of the building under different earthquake intensities. The THA method is a nonlinear static analysis method used to evaluate the performance of a building under gradually increasing static targets, and can obtain a pushover curve, which is used to describe the building's resistance to force until the structure relaxes, local or overall collapse. In addition, the seismic resilience evaluation method at the urban community scale based on CIM can effectively predict the offset distance, range, speed, etc. of each floor of each building for ordinary buildings with regular plane and vertical layout, and realize the evaluation of building seismic disasters at the community scale. However, the above methods mainly focus on building site selection and the design of the seismic performance of building structures, and insufficient consideration is given to risks such as falling objects, blockages, and building collapses that may exist in the surrounding space of buildings during an earthquake.

[0004] Although the above methods can evaluate earthquake risks to a certain extent, the existing methods focus on the seismic performance of the building's main structure, the prediction of earthquake damage is relatively rough, the spatial risk of earthquake disasters is unclear, and it is difficult to conduct safety planning before disasters, effectively prevent disasters, and guide residents to quickly and safely avoid risk areas during disasters. Therefore, paying attention to the risks in the space around buildings during earthquakes is of great significance for the safety and efficiency of evacuation. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for evaluating the spatial risk of earthquake damage to urban buildings based on GIS, which can evaluate the earthquake damage risk of a spatial area and provide a basis for risk control in disaster prevention and mitigation planning.

[0006] To achieve the above purpose, the present invention provides a method for evaluating the spatial risk of earthquake damage to urban buildings based on GIS, including the following steps:

[0007] S1. Obtain the spatial basic attribute data, earthquake history data, fault activity data, earthquake intensity distribution data, and site condition data of the buildings in the area, construct a three-dimensional model of the buildings, and integrate the earthquake disaster database;

[0008] S2. Construct a simulation model of the earthquake damage scenario, use nonlinear time history analysis to obtain the maximum displacement of the buildings, and generate a heat map of the maximum displacement of the buildings;

[0009] S3. Based on the building characteristics and earthquake motion parameters, obtain the generation probability of secondary falling objects of the buildings, calculate the trajectories of the falling objects, obtain a zoning map of the falling object risk, and generate a heat map of the falling object risk;

[0010] S4. Divide the spatial area, and obtain the earthquake damage risk of the spatial unit according to the heat map of the maximum displacement of the buildings and the heat map of the falling object risk;

[0011] S5. Based on the earthquake disaster database, obtain the risk values of each spatial unit in the area and visualize them.

[0012] Preferably, step S2 includes:

[0013] Based on the structural attributes and site conditions of the buildings, establish a nonlinear time history analysis model for each building;

[0014] Based on the earthquake motion parameters, set the initial conditions and boundary conditions, and use the motion equation to simulate the response of the buildings under earthquake action, obtain the maximum displacement of the buildings, and visualize the building displacements.

[0015] Preferably, the motion equation is:

[0016]

[0017] In the formula, M is the mass matrix, C is the damping matrix, is the restoring force vector of the structure, u(t) is the nodal displacement vector, is the nodal velocity vector, ü(t) is the nodal acceleration vector, a g (t) is the earthquake acceleration record.

[0018] Preferably, based on the motion equation, the Newmark-beta method is used to solve the nodal displacement of the building, and then the maximum displacement of the building is obtained as follows:

[0019]

[0020] u max =max n ∥u n ∥

[0021] In the formula, u n+1 、u n are the nodal displacement vectors at the (n + 1)-th and n-th time steps respectively, is the nodal velocity vector at the n-th time step, ü n 、ü n+1 are the nodal velocity vectors at the n-th and (n + 1)-th time steps respectively, Δt is the time step, β is the Newmark parameter, u max is the maximum displacement of the building.

[0022] Preferably, in step S3, the probability of secondary falling objects generation and the trajectory of falling objects are as follows:

[0023] P f =f(S,H,M,a,T)

[0024]

[0025]

[0026] In the formula, P f is the probability of secondary falling objects generation, S is the building structure type parameter, H is the building height, M is the external wall material and fixing method parameter, a is the peak ground acceleration, T is the earthquake duration, x 0 、h 0 are the building coordinates and height respectively, v 0 is the initial velocity of the falling object, h(t) is the height of the falling object at time t, x(t) is the coordinate of the falling object at time t, and g is the acceleration due to gravity.

[0027] Preferably, in step S4, the seismic damage risk of the spatial unit building is obtained as follows:

[0028]

[0029] In the formula, R i is the seismic damage risk of the i-th spatial unit, P f,j is the probability of falling object generation of the j-th building, d ij is the distance between the i-th spatial unit and the j-th building, u max,j is the maximum displacement of the j-th building.

[0030] Therefore, the present invention adopts the above-mentioned method for spatial risk assessment of urban building seismic damage, and has the following technical effects:

[0031] (1) By using the above method, it is possible to conduct spatial risk simulation analysis before a disaster occurs, clarify the rigid control area and the emergency evacuation safety area, enhance the risk management ability, and improve the emergency response efficiency and safety.

[0032] (2) Combining nonlinear time history analysis and the probability of secondary falling object generation, a comprehensive risk assessment model is established to accurately identify the spatial distribution of building seismic damage risks, improve the accuracy and precision of risk identification, and is conducive to making spatial planning and emergency evacuation route planning in advance to ensure the safe evacuation of the emergency population.

[0033] (3) Based on the GIS platform, the obtained seismic damage risks are visualized, which is more intuitive and intelligent, and can help the emergency management department and residents better understand the risk distribution and improve the processing efficiency.

[0034] (4) The output results formed based on GIS can be matched with the content in the urban planning text compilation, have high usability and strong coordination, can be synergistically integrated with other data, and provide practical support for planning decisions.

[0035] Next, through embodiments, the technical solutions of the present invention will be further described in detail. Specific Embodiments

[0036] The present invention can be more detailedly explained through the following embodiments. The purpose of disclosing the present invention is to protect all changes and improvements within the scope of the present invention. The present invention is not limited to the following embodiments.

[0037] A method for spatial risk assessment of urban building seismic damage provided by the present invention includes the following steps:

[0038] S1. Obtain the spatial basic attribute data, earthquake history data, fault activity data, earthquake intensity distribution data, and site condition data of the buildings in the area, construct a three-dimensional model of the buildings, and integrate the earthquake disaster database.

[0039] Among them, the basic attribute data of all buildings in the area are collected through investigation and survey data, satellite remote sensing images, UAV images, etc., including the geographical location, height, number of floors, structural type, construction year, etc. of the buildings; historical earthquake data, fault activity data, earthquake intensity distribution data are collected through historical materials and disaster monitoring stations; the obtained site condition data include soil type, geological structure, and groundwater level, etc.

[0040] Import the basic spatial attribute data of buildings, seismic hazard, and site condition data into the GIS platform for spatial data integration and preprocessing, including data cleaning, coordinate registration, and data format conversion, etc.; and based on the spatial basic attribute information of the buildings, construct a 3D model of the buildings on the GIS platform, and then integrate the earthquake disaster database.

[0041] S2. Build a seismic damage scenario simulation model, obtain the maximum displacement of the buildings, and perform visualization to generate a heat map of the maximum displacement of the buildings, as follows:

[0042] Based on the structural attributes and site conditions of the buildings, establish a nonlinear time history analysis model for each building; input the ground motion parameters, set the initial conditions and boundary conditions, and use the motion equation to simulate the response of the buildings under earthquake action, obtain the displacement time history and velocity time history of each floor of the buildings, so as to obtain the maximum displacement of the buildings.

[0043] Among them, the motion equation is:

[0044]

[0045] In the formula, M is the mass matrix; C is the damping matrix; is the restoring force vector of the structure, and the nonlinear effect is considered; u(t) is the nodal displacement vector; is the nodal velocity vector; ü(t) is the nodal acceleration vector; a g (t) is the earthquake acceleration record.

[0046] Based on the above motion equation, use the Newmark-beta method to calculate the nodal displacement of the buildings, as follows:

[0047]

[0048] In the formula, u n+1 、u n are the nodal displacement vectors at the (n + 1)-th and n-th time steps respectively; is the nodal velocity vector at the n-th time step; ü n 、ü n+1They are the nodal velocity vectors at the nth and (n + 1)th time steps respectively; Δt is the time step; β is the Newmark parameter, usually taken as β = 1 / 4 to ensure unconditional stability.

[0049] In summary, the maximum displacement u of the building is obtained max as:

[0050] u max = max n ∥u n ∥

[0051] Import the building and displacement data into the GIS platform, create a new layer that contains the geographical location of each building and its corresponding maximum displacement value, visualize the maximum displacements of different buildings using color gradients, and use corresponding legends to illustrate; among them, the darker the color, the greater the maximum displacement, and the lighter the color, the smaller the maximum displacement, to generate a heat map or contour map of the maximum displacement. According to the heat map generated from the maximum displacement values of the buildings, display the displacement distribution of the entire area and identify the buildings and areas with high displacement and high risk.

[0052] S3. Use the building characteristics and ground motion parameters to calculate the generation probability of secondary falling objects for each building. At the same time, calculate the trajectory of the falling objects, determine the range of the landing points, and generate a falling object risk zoning map on the GIS platform. Use color gradients, heat maps, and legends to clearly identify high, medium, and low risk areas, and intuitively display the buildings and their falling object risk areas through 3D models.

[0053] Among them, the expression of the generation probability P of secondary falling objects f is:

[0054] P f = f(S, H, M, a, T)

[0055] In the formula, S is the building structure type parameter, H is the building height, M is the outer wall material and fixing method parameter, a is the peak ground acceleration, and T is the earthquake duration.

[0056] According to the building coordinates x 0 , height h 0 , and the initial velocity v of the falling object 0 , calculate the trajectory of the falling object as follows:

[0057]

[0058]

[0059] In the formula, h(t) is the height of the falling object at time t, x(t) is the coordinate of the falling object at time t, and g is the acceleration due to gravity.

[0060] Draw a secondary falling object risk area map on the GIS platform to identify high-risk areas outside the building and adjacent roads.

[0061] S4. According to the maximum displacement heat map of the building and the secondary falling object risk area map, divide the research area into several spatial units (grids). The size of each unit is determined according to needs, and calculate the seismic damage risk of the spatial unit as follows:

[0062]

[0063] In the formula, R i is the seismic damage risk of the i-th spatial unit, P f,j is the falling object generation probability of the j-th building, d ij is the distance between the i-th spatial unit and the j-th building, u max,j is the maximum displacement of the j-th building.

[0064] S5. Based on the earthquake disaster database, obtain the spatial seismic damage risk value in the region and visualize the seismic damage spatial risk as follows:

[0065] Load the earthquake disaster database into the GIS platform. According to the methods in steps S2 - S4, calculate the risk value of each spatial unit, and through the visualization tool of the GIS platform, generate a spatial seismic damage risk heat map based on the seismic damage risk value of each spatial unit. Represent different seismic damage risk levels through color gradients (dark colors are used for high-risk areas and light colors are used for low-risk areas), and add a legend to the spatial seismic damage risk heat map to explain the risk level represented by the color.

[0066] Add labels of important buildings, roads, shelters, etc. to help understanding and decision-making, and output the result report in the form of charts, 3D models, and spatial seismic damage risk heat maps to visually display the seismic damage risks in different regions.

[0067] Therefore, by adopting the above-mentioned method for evaluating the spatial seismic damage risk of urban buildings based on GIS, the present invention can obtain a visual spatial seismic damage risk heat map, provide a risk control basis for disaster prevention and mitigation planning, and provide decision-making support in aspects such as building reinforcement, delineation of evacuation areas, and planning of emergency evacuation routes, so as to enhance the seismic resilience of the city.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify or equivalently replace the technical solutions of the present invention, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A spatial risk assessment method for earthquake damage to urban buildings based on GIS, characterized in that: The following steps are involved: S1. Obtain spatial basic attribute data, earthquake history data, fault activity data, earthquake intensity distribution data and site condition data of buildings in the area, build a three-dimensional model of the building, and integrate the earthquake disaster database; S2. Construct a simulation model of earthquake damage scenarios, use nonlinear time history analysis to obtain the maximum displacement of buildings, and generate a thermal map of the maximum displacement of buildings; S3. Based on the building characteristics and seismic parameters, the secondary falling object generation probability of the building is obtained, and the falling object trajectory is calculated to obtain the falling object risk zoning map and generate the falling object risk heat map; The probability of secondary falling objects and their trajectories are as follows: P f =f(S,H,M,a,T) Where P f is the probability of secondary falling objects, S is the building structure type parameter, H is the building height, M is the exterior wall material and fixing method parameter, a is the earthquake peak acceleration, T is the earthquake duration, x0 and h0 are the building coordinates and height respectively, v0 is the initial velocity of the falling object, h(t) is the height of the falling object at time t, x(t) is the coordinates of the falling object at time t, and g is the gravitational acceleration; S4. Divide the spatial area and obtain the earthquake damage risk of the spatial unit according to the maximum displacement thermal map of the building and the falling object risk thermal map, as follows: In the formula, R i is the earthquake damage risk of the ith spatial unit, P f,j is the probability of falling objects generated by the j-th building, d ij is the distance between the i-th spatial unit and the j-th building, u max,j The maximum displacement of the jth building; S5. Based on the earthquake disaster database, the earthquake damage risk value of each spatial unit in the region is obtained and visualized.

2. The GIS-based urban building earthquake damage spatial risk assessment method according to claim 1 is characterized in that: Step S2 includes: Based on the structural properties of the buildings and site conditions, a nonlinear time-history analysis model for each building is established; Based on the seismic parameters, the initial and boundary conditions are set, and the motion equation is used to simulate the response of the building under the action of the earthquake, obtain the maximum displacement of the building, and visualize the displacement of the building.

3. The GIS-based urban building earthquake damage spatial risk assessment method according to claim 2 is characterized in that: The equation of motion is: Where M is the mass matrix, C is the damping matrix, is the restoring force vector of the structure, u(t) is the node displacement vector, is the node velocity vector, is the node acceleration vector, a g (t) is the earthquake acceleration record.

4. The GIS-based urban building earthquake damage spatial risk assessment method according to claim 3 is characterized in that: Based on the equation of motion, the Newmark-beta method is used to solve the displacement of the building nodes, and then the maximum displacement of the building is obtained, as follows: u max =max n ||u n || In the formula, u n+1 、u n are the node displacement vectors at the n+1th and nth time steps respectively, is the node velocity vector at the nth time step, are the node velocity vectors at the nth and n+1th time steps, Δt is the time step, β is the Newmark parameter, and u max is the maximum displacement of the building.

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