技术领域Technical Field
本发明涉及拱桥技术领域，更具体的说是涉及一种大跨拱桥服役状态评估方法及系统。The present invention relates to the technical field of arch bridges, and more particularly to a method and system for evaluating the service status of a long-span arch bridge.
背景技术Background technique
大跨拱桥因其结构刚度大、经济性好、山区适应性强等显著优势，已成为交通路网跨越山地、峡谷的重要桥型。然而，随着服役年限的增长，大跨拱桥在环境侵蚀、重载交通等多因素的共同作用下不可避免的发生性能退化。因此，准确评估大跨拱桥的服役状态对于保障桥梁运营安全、延长桥梁使用寿命具有重要意义。Due to its significant advantages such as high structural rigidity, good economy and strong adaptability in mountainous areas, long-span arch bridges have become an important type of bridge for transportation networks across mountains and canyons. However, with the increase in service life, long-span arch bridges inevitably experience performance degradation due to the combined effects of environmental erosion, heavy traffic and other factors. Therefore, accurately evaluating the service status of long-span arch bridges is of great significance to ensure the safety of bridge operation and extend the service life of bridges.
目前，拱桥服役状态评估方法可分为两类，即荷载试验法和有限元模型修正法。荷载试验法通过在桥梁结构上施加与设计荷载或使用荷载基本相当的外载，通过测试桥梁结构在试验荷载作用下的挠度、应力等指标，将测试结果与结构相应荷载作用下的计算值或有关规范规定值作比较，从而评定出桥梁结构的承载能力。荷载试验法虽直观有效，但是需要中断交通，试验周期较长，不具备实时性、快速评估的特点，且经济成本较高。有限元模型修正法主要根据拱桥现场实测结果，通过修正有限元模型来反映结构实际的工作状态，进而利用修正后的模型来分析桥梁的安全状态。但是，有限元模型修正法往往涉及到精细化有限元模型建立以及大量修正参数的迭代计算，导致计算工作量大，评估过程极为耗时，无法实现拱桥快速评估的目标。At present, the service status assessment methods of arch bridges can be divided into two categories, namely, load test method and finite element model modification method. The load test method applies an external load that is basically equivalent to the design load or service load on the bridge structure, tests the deflection, stress and other indicators of the bridge structure under the test load, and compares the test results with the calculated values or the values specified in the relevant specifications under the corresponding load of the structure, so as to assess the bearing capacity of the bridge structure. Although the load test method is intuitive and effective, it requires interruption of traffic, has a long test cycle, does not have the characteristics of real-time and rapid assessment, and has a high economic cost. The finite element model modification method mainly reflects the actual working status of the structure by modifying the finite element model based on the on-site measurement results of the arch bridge, and then uses the modified model to analyze the safety status of the bridge. However, the finite element model modification method often involves the establishment of a refined finite element model and the iterative calculation of a large number of correction parameters, resulting in a large amount of calculation workload and an extremely time-consuming evaluation process, which cannot achieve the goal of rapid evaluation of arch bridges.
因此，如何快速评估大跨拱桥的服役状态是本领域技术人员亟需解决的问题。Therefore, how to quickly evaluate the service status of a long-span arch bridge is an urgent problem that technical personnel in this field need to solve.
发明内容Summary of the invention
有鉴于此，本发明提供了一种大跨拱桥服役状态评估方法，通过轻量化卷积神经网络模型实时识别过桥车辆载荷，通过服役环境下大跨拱桥拱轴线形快速获取理论极限响应，进而实现大跨拱桥服役状态的快速评估。In view of this, the present invention provides a method for evaluating the service status of a large-span arch bridge, which uses a lightweight convolutional neural network model to identify the load of vehicles crossing the bridge in real time, and quickly obtains the theoretical limit response through the arch axis shape of the large-span arch bridge under the service environment, thereby realizing a rapid evaluation of the service status of the large-span arch bridge.
为了实现上述目的，本发明提供如下技术方案：In order to achieve the above object, the present invention provides the following technical solutions:
本发明公开了一种大跨拱桥服役状态评估方法，具体步骤如下：The present invention discloses a method for evaluating the service status of a long-span arch bridge, and the specific steps are as follows:
S1：获取运行条件下过桥车辆荷载引起的桥梁位移实测真实响应；S1: Obtain the measured real response of bridge displacement caused by vehicle loads under operating conditions;
S2：通过荷载识别算法，建立过桥车辆荷载与大跨拱桥结构响应的映射关系，根据所述实测真实响应，实时识别过桥车辆荷载；S2: Establishing a mapping relationship between the vehicle load on the bridge and the structural response of the long-span arch bridge through a load identification algorithm, and identifying the vehicle load on the bridge in real time according to the measured real response;
S3：根据大跨拱桥实际拱轴线形，计算过桥车辆荷载下大跨拱桥的理论极限响应；S3: Calculate the theoretical limit response of the long-span arch bridge under the load of vehicles passing through the bridge according to the actual arch axis shape of the long-span arch bridge;
S4：通过所述实测真实响应与所述理论极限响应的包络对比，评估大跨拱桥的服役状态。S4: Evaluate the service status of the long-span arch bridge by comparing the envelope of the measured true response with the theoretical limit response.
进一步的，所述S1包括：获取运行条件下大跨拱桥主拱跨截面在固定时间内的竖向位移响应，然后利用卡尔曼滤波剔除所述竖向位移响应中的温度效应，得到所述实测真实响应。Furthermore, S1 includes: obtaining the vertical displacement response of the main arch span section of the long-span arch bridge under operating conditions within a fixed time, and then using Kalman filtering to eliminate the temperature effect in the vertical displacement response to obtain the measured true response.
进一步的，所述S2包括：Further, the S2 includes:
S201：建立大跨拱桥的车桥耦合动力学模型：S201: Establish a vehicle-bridge coupling dynamics model for a long-span arch bridge:
S202：生成车辆荷载工况，并根据所述车桥耦合动力学模型，获取不同车辆荷载下大跨拱桥的结构响应，利用小波变换将所述结构响应转换为对应的时频图；S202: generating a vehicle load condition, and obtaining the structural response of the long-span arch bridge under different vehicle loads according to the vehicle-bridge coupling dynamics model, and converting the structural response into a corresponding time-frequency diagram using wavelet transform;
S203：以所述时频图为输入，对应的车辆荷载作为输出，利用轻量化卷积神经网络MobileNetV2建立大跨拱桥结构响应时频图与车辆荷载的映射关系；S203: using the time-frequency graph as input and the corresponding vehicle load as output, a mapping relationship between the time-frequency graph of the structural response of the long-span arch bridge and the vehicle load is established using a lightweight convolutional neural network MobileNetV2;
S204：根据所述实测真实响应，实时识别过桥车辆荷载。S204: Identify the load of vehicles crossing the bridge in real time according to the measured real response.
进一步的，所述S3包括：Further, the S3 includes:
S301：考虑环境温度变化、拱肋损伤影响，基于大跨拱桥真实拱轴线形，构建大跨拱桥服役条件下的几何非线性控制微分方程；S301: Considering the influence of ambient temperature change and arch rib damage, based on the real arch axis shape of the long-span arch bridge, the geometric nonlinear control differential equation of the long-span arch bridge under service conditions is constructed;
S302：根据所述几何非线性控制微分方程，结合样条函数理论和Newton-Raphson法，计算各节点处拱肋竖向位移、水平位移、截面轴力、截面弯矩；S302: Calculate the vertical displacement, horizontal displacement, section axial force, and section bending moment of the arch rib at each node according to the geometric nonlinear control differential equation, combined with the spline function theory and the Newton-Raphson method;
S303：计算各节点处截面形心应变和曲率；S303: Calculate the centroid strain and curvature of the cross section at each node;
S304：根据弯矩和曲率的关系，以及轴力和形心应变的关系，迭代计算各节点处的截面真实弯矩和截面真实轴力；S304: Iteratively calculate the true bending moment and true axial force of the section at each node according to the relationship between the bending moment and the curvature, and the relationship between the axial force and the centroid strain;
S305：根据各节点处所述截面真实弯矩、所述截面真实轴力，计算各节点处截面抗弯刚度、抗压刚度；S305: Calculate the bending stiffness and compressive stiffness of the cross section at each node according to the true bending moment and the true axial force of the cross section at each node;
S306：更新各节点处截面抗弯刚度和抗压刚度，重复步骤S301-S305，直到截面满足内力平衡条件；所述内力平衡条件为：更新截面抗弯刚度和抗压刚度前，所述几何非线性控制微分方程计算得到的截面轴力和截面弯矩计算值，与更新后的截面轴力和截面弯矩计算值相等；S306: updating the bending stiffness and compressive stiffness of the cross section at each node, and repeating steps S301-S305 until the cross section satisfies the internal force balance condition; the internal force balance condition is: before updating the bending stiffness and compressive stiffness of the cross section, the calculated values of the cross section axial force and cross section bending moment calculated by the geometric nonlinear control differential equation are equal to the updated calculated values of the cross section axial force and cross section bending moment;
S307：判断各节点处截面是否发生破坏，若未发生破坏，则施加下一荷载增量步，重复步骤S301-S306；若发生破坏，则输出得到大跨拱桥的极限响应。S307: Determine whether the cross section at each node is damaged. If not, apply the next load increment and repeat steps S301-S306. If damage occurs, output the ultimate response of the long-span arch bridge.
进一步的，S302中所述几何非线性控制微分方程为：Furthermore, the geometrically nonlinear control differential equation in S302 is:
式中，ω和δ分别为拱的竖向位移和水平位移，MA和MB分别为左、右拱脚弯矩，H代表拱脚水平推力，VA为左拱脚竖向反力，x为拱的横坐标；系数C1、C2、C3、C4、C5满足如下关系：Where ω and δ are the vertical displacement and horizontal displacement of the arch respectively,MA andMB are the bending moments of the left and right arch feet respectively, H represents the horizontal thrust of the arch foot,VA is the vertical reaction force of the left arch foot, and x is the horizontal coordinate of the arch; the coefficientsC1 ,C2 ,C3 ,C4 , andC5 satisfy the following relationship:
式中，y代表大跨拱桥实际拱轴方程，y′代表y的一阶导数，y″代表y的二阶导数，EI和EA分别为截面抗弯刚度和抗压刚度，ξ＝x/l，l代表拱桥计算跨径，Mx表示荷载作用下相应简支曲梁任意截面弯矩，t为截面上下缘升温之和，Δt为截面上下缘的温差，α为材料的线膨胀系数，d为截面高度。Where y represents the actual arch axis equation of the long-span arch bridge, y′ represents the first-order derivative of y, y″ represents the second-order derivative of y, EI and EA are the section bending stiffness and compressive stiffness respectively, ξ＝x/l, l represents the calculated span of the arch bridge,Mx represents the bending moment of any section of the corresponding simply supported curved beam under load, t is the sum of the temperature rise of the upper and lower edges of the section, Δt is the temperature difference between the upper and lower edges of the section, α is the linear expansion coefficient of the material, and d is the section height.
进一步的，S303中计算公式如下：Furthermore, the calculation formula in S303 is as follows:
式中，si和s′i分别代表第i个离散节段变形前后的弧长，ε0为第i个节点处截面形心应变，为第i个节点处截面曲率，ωi和δi分别为第i个节点的竖向和水平位移，ω′为ωi的一阶导数，ω″为的二阶导数，xi为第i个节点处水平坐标，yi为第i个节点处竖向坐标。Wheresi ands′i represent the arc lengths of the ith discrete segment before and after deformation,ε0 is the centroid strain of the cross section at the ith node, is the section curvature at the i-th node, ωi and δi are the vertical and horizontal displacements of the i-th node, ω′ is the first-order derivative of ωi , ω″ is the second-order derivative of ,xi is the horizontal coordinate at the i-th node, andyi is the vertical coordinate at the i-th node.
进一步的，S305中所述截面真实弯矩M的计算公式如下：Furthermore, the calculation formula of the true bending moment M of the section in S305 is as follows:
式中，n＝N0/Nu代表轴压比，Nu为截面的轴压极限轴力，B4(n)、B5(n)为折线斜率，通过纤维模型法确定，Mcr(n)为截面开裂弯矩，分别是截面开裂曲率和极限曲率；Where n = N0 /Nu represents the axial compression ratio,Nu is the axial compression limit axial force of the section, B4 (n) and B5 (n) are the broken line slopes determined by the fiber model method,Mcr (n) is the section cracking moment, They are the cross-section cracking curvature and limiting curvature respectively;
所述截面真实轴力N的计算公式如下：The calculation formula of the true axial force N of the section is as follows:
N＝P1(m)ε2+P2(m)ε+P3(m),M＜Mu；N＝P1 (m)ε2 +P2 (m)ε+P3 (m), M＜Mu ;
式中，m＝M/Mu代表弯矩比，Mu为截面的纯弯极限弯矩，P1(m)、P2(m)、P3(m)分别代表二次抛物线的系数，通过纤维模型法确定，ε为截面形心应变；Where, m = M/Mu represents the moment ratio,Mu is the pure bending limit moment of the section, P1 (m), P2 (m), and P3 (m) represent the coefficients of the quadratic parabola, respectively, which are determined by the fiber model method, and ε is the centroid strain of the section;
迭代计算时，首先令N0＝N′，N′为根据所述几何非线性控制微分方程计算得到的截面轴力，然后根据N0计算M值，并基于M值计算N值，直至N＝N0。During iterative calculation, firstly, N0 =N′ is set, where N′ is the cross-sectional axial force calculated according to the geometric nonlinear control differential equation, and then the M value is calculated according to N0 , and the N value is calculated based on the M value until N=N0 .
进一步的，S307中根据下式判断截面是否发生破坏：Furthermore, in S307, whether the cross section is damaged is determined according to the following formula:
f(n,m)-1＝0；f(n,m)-1＝0;
式中，n和m分别代表截面的轴压比与弯矩比，f(n,m)为截面的广义屈服函数，广义屈服函数根据不同拱圈截面通过数值计算确定。Where n and m represent the axial compression ratio and bending moment ratio of the section respectively, and f(n,m) is the generalized yield function of the section. The generalized yield function is determined by numerical calculation according to different arch ring sections.
本发明还公开了一种大跨拱桥服役状态评估系统，包括：依次数据连接的真实响应获取模块、车辆载荷识别模块、理论极限计算模块、评估模块，并且，所述真实响应获取模块还与所述评估模块数据连接；The present invention also discloses a long-span arch bridge service status assessment system, comprising: a real response acquisition module, a vehicle load identification module, a theoretical limit calculation module, and an assessment module which are sequentially data-connected, and the real response acquisition module is also data-connected to the assessment module;
所述真实响应获取模块：获取运行条件下过桥车辆荷载的实测真实响应；The real response acquisition module is used to acquire the measured real response of the vehicle load over the bridge under the operating conditions;
所述车辆载荷识别模块：通过荷载识别算法，建立过桥车辆荷载与大跨拱桥结构响应的映射关系，根据所述实测真实响应，实时识别过桥车辆荷载；The vehicle load identification module: establishes a mapping relationship between the vehicle load on the bridge and the structural response of the long-span arch bridge through a load identification algorithm, and identifies the vehicle load on the bridge in real time according to the measured real response;
所述理论极限计算模块：根据大跨拱桥实际拱轴线形，计算过桥车辆荷载下大跨拱桥的理论极限响应；The theoretical limit calculation module is used to calculate the theoretical limit response of the long-span arch bridge under the load of vehicles passing through the bridge according to the actual arch axis shape of the long-span arch bridge;
所述评估模块：通过所述实测真实响应与所述理论极限响应的包络对比，评估大跨拱桥的服役状态。The evaluation module evaluates the service status of the long-span arch bridge by comparing the envelope of the measured true response with the theoretical limit response.
经由上述的技术方案可知，与现有技术相比，本发明公开提供了一种大跨拱桥服役状态评估方法及系统，利用轻量化卷积神经网络MobileNetV2，通过少量的参数、极低计算资源，实时快速识别过桥车辆荷载，保障了拱桥服役状态快速评估的可实现性；并且基于拱轴线形与大跨拱桥极限响应的本质联系，考虑环境温度变化、拱肋刚度退化引起的拱轴线形演变，提出了基于真实拱轴线形的大跨拱桥极限响应计算方法，无需精细化有限元模型建立，仅需获取服役环境下大跨拱桥拱轴线形，即可快速获取理论极限响应，进而实现了大跨拱桥服役状态的快速评估。It can be seen from the above technical scheme that compared with the prior art, the present invention discloses a method and system for evaluating the service status of a large-span arch bridge. It uses a lightweight convolutional neural network MobileNetV2 to quickly identify the load of vehicles crossing the bridge in real time through a small number of parameters and extremely low computing resources, thereby ensuring the feasibility of rapid evaluation of the service status of the arch bridge. Moreover, based on the essential connection between the arch axis shape and the ultimate response of the large-span arch bridge, the evolution of the arch axis shape caused by changes in ambient temperature and degradation of the arch rib stiffness is considered, and a method for calculating the ultimate response of a large-span arch bridge based on the real arch axis shape is proposed. There is no need to establish a refined finite element model. Only the arch axis shape of the large-span arch bridge under the service environment needs to be obtained to quickly obtain the theoretical ultimate response, thereby realizing rapid evaluation of the service status of the large-span arch bridge.
附图说明BRIEF DESCRIPTION OF THE DRAWINGS
为了更清楚地说明本发明实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据提供的附图获得其他的附图。In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.
图1为本发明的整体流程示意图。FIG1 is a schematic diagram of the overall process of the present invention.
图2为本发明的理论极限响应计算流程示意图。FIG. 2 is a schematic diagram of a theoretical limit response calculation flow of the present invention.
图3为本发明实施例主拱跨中截面在某一时间段内的竖向位移响应示意图。FIG3 is a schematic diagram of the vertical displacement response of the mid-span section of the main arch in a certain time period according to an embodiment of the present invention.
图4为本发明实施例分离得到的过桥车辆荷载响应示意图。FIG4 is a schematic diagram of the load response of vehicles crossing the bridge separated according to an embodiment of the present invention.
图5为本发明实施例车辆荷载响应小波时频图；FIG5 is a wavelet time-frequency diagram of vehicle load response according to an embodiment of the present invention;
图6为本发明实施例过桥车辆荷载的识别结果示意图。FIG. 6 is a schematic diagram of the identification result of the vehicle load passing over the bridge according to an embodiment of the present invention.
图7为本发明实施实测真实车辆荷载响应与理论极限响应的包络对比示意图。FIG. 7 is a schematic diagram showing the envelope comparison between the actual vehicle load response and the theoretical limit response according to the present invention.
具体实施方式Detailed ways
下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
下面对本发明的一种大跨拱桥服役状态评估方法进行详细说明，以大跨上承式钢筋混凝土拱桥为例对桥梁的服役状态进行具体的快速评估操作和结果验证，本实施例所采用的桥梁主拱拱轴线采用悬链线，计算跨径为600m，矢高为125m，矢跨比f/l＝1/4.8，拱轴系数m＝1.9，拱箱单肋采用单箱单室变高度截面，拱顶截面高8m，拱脚截面高12m，宽6.5m，拱肋横向中心距16.5m。横向设置梁两片肋，为平行拱形式。混凝土拱肋采用钢管混凝土桁架结构作为劲性骨架，桁架上弦管外径900mm，钢管壁厚从拱脚到拱顶由30mm变化为35mm，下弦管外径900mm，壁厚从拱脚到拱顶由35mm变化为30mm，钢材采用Q420qD25Z。拱肋外部混凝土采用C60，主弦管内灌注C80自密实微膨胀混凝土。The following is a detailed description of a method for evaluating the service status of a large-span arch bridge of the present invention. Taking a large-span top-bearing reinforced concrete arch bridge as an example, a specific rapid evaluation operation and result verification are performed on the service status of the bridge. The main arch axis of the bridge used in this embodiment adopts a catenary, the calculated span is 600m, the rise is 125m, the rise-span ratio f/l=1/4.8, the arch axis coefficient m=1.9, the arch box single rib adopts a single-box single-chamber variable height section, the arch top section is 8m high, the arch foot section is 12m high, the width is 6.5m, and the arch rib transverse center distance is 16.5m. Two ribs of the beam are arranged transversely, in the form of parallel arches. The concrete arch rib adopts a steel tube concrete truss structure as a rigid skeleton, the outer diameter of the truss upper chord tube is 900mm, the wall thickness of the steel tube changes from 30mm to 35mm from the arch foot to the arch top, the outer diameter of the lower chord tube is 900mm, the wall thickness changes from 35mm to 30mm from the arch foot to the arch top, and the steel material is Q420qD25Z. The external concrete of the arch rib is C60, and the main chord is poured with C80 self-compacting slightly expansive concrete.
本发明实施例公开了一种大跨拱桥服役状态评估方法，如图1所示，具体步骤如下：The embodiment of the present invention discloses a method for evaluating the service status of a long-span arch bridge, as shown in FIG1 , and the specific steps are as follows:
S1：获取运行条件下过桥车辆荷载引起的桥梁位移实测真实响应；S1: Obtain the measured real response of bridge displacement caused by vehicle loads under operating conditions;
S2：通过荷载识别算法，建立过桥车辆荷载与大跨拱桥结构响应的映射关系，根据实测真实响应，实时识别过桥车辆荷载；S2: Through the load identification algorithm, the mapping relationship between the vehicle load on the bridge and the structural response of the long-span arch bridge is established, and the vehicle load on the bridge is identified in real time based on the measured real response;
S3：根据大跨拱桥实际拱轴线形，计算过桥车辆荷载下大跨拱桥的理论极限响应；S3: Calculate the theoretical limit response of the long-span arch bridge under the load of vehicles passing through the bridge according to the actual arch axis shape of the long-span arch bridge;
S4：通过实测真实响应与理论极限响应的包络对比，评估大跨拱桥的服役状态。S4: Evaluate the service status of long-span arch bridges by comparing the envelope of measured true response with the theoretical limit response.
在一个具体的实施例中，S1包括：通过健康监测系统获获取运行条件下大跨拱桥主拱跨截面在固定时间内的竖向位移响应，然后利用卡尔曼滤波剔除竖向位移响应中的温度效应，得到实测真实响应。如图3所示，获取了桥梁主拱跨中截面在某一时间段内的竖向位移响应，从图3中可以看出，结构的竖向位移响应波动剧烈，包含多种效应成分，因此需要剔除无关成分，获得车辆荷载下的结构响应。如图4所示，根据温度效应与车辆荷载效应时间尺度上的差异，利用卡尔曼滤波剔除了结构实际响应中的温度效应，得到了过桥车辆荷载产生的响应。从图4中可以看出，剔除温度效应后，响应曲线更符合随机车辆荷载产生的响应，有助于车辆荷载的精准识别和结构服役状态的准确评估。In a specific embodiment, S1 includes: obtaining the vertical displacement response of the main arch span section of the long-span arch bridge under operating conditions within a fixed time through a health monitoring system, and then using Kalman filtering to eliminate the temperature effect in the vertical displacement response to obtain the measured true response. As shown in Figure 3, the vertical displacement response of the mid-span section of the main arch of the bridge within a certain period of time is obtained. It can be seen from Figure 3 that the vertical displacement response of the structure fluctuates violently and contains multiple effect components. Therefore, it is necessary to eliminate irrelevant components to obtain the structural response under vehicle load. As shown in Figure 4, based on the difference in time scale between the temperature effect and the vehicle load effect, the temperature effect in the actual response of the structure is eliminated by using Kalman filtering, and the response generated by the vehicle load passing the bridge is obtained. As can be seen from Figure 4, after eliminating the temperature effect, the response curve is more consistent with the response generated by random vehicle loads, which is helpful for the accurate identification of vehicle loads and the accurate evaluation of the service status of the structure.
在一个具体的实施例中，S2包括：In a specific embodiment, S2 includes:
S201：建立大跨拱桥的车桥耦合动力学模型：S201: Establish a vehicle-bridge coupling dynamics model for a long-span arch bridge:
S202：生成车辆荷载工况，并根据车桥耦合动力学模型，获取不同车辆荷载下大跨拱桥的结构响应，利用小波变换将结构响应转换为对应的时频图；S202: Generate vehicle load conditions, and obtain the structural response of the long-span arch bridge under different vehicle loads according to the vehicle-bridge coupling dynamics model, and convert the structural response into a corresponding time-frequency diagram using wavelet transform;
S203：以时频图为输入，对应的车辆荷载作为输出，利用轻量化卷积神经网络建立大跨拱桥结构响应时频图与车辆荷载的映射关系；S203: using the time-frequency graph as input and the corresponding vehicle load as output, a lightweight convolutional neural network is used to establish a mapping relationship between the time-frequency graph of the long-span arch bridge structure response and the vehicle load;
S204：根据实测真实响应，实时识别过桥车辆荷载。S204: Identify the load of vehicles crossing the bridge in real time according to the measured real response.
利用小波变换将车辆荷载大跨拱桥的结构响应转换为时频图，结果如图5所示；将小波时频图输入到设计好的轻量化卷积神经网络MobileNetV2中，得到了过桥车辆荷载的识别结果，如图6所示。从图6中可以看出，该时段共有五辆车通过桥梁，此外，识别出过桥车辆仅用时0.1s，极为快速、实时性高。The structural response of the long-span arch bridge under vehicle load is converted into a time-frequency diagram using wavelet transform, and the result is shown in Figure 5. The wavelet time-frequency diagram is input into the designed lightweight convolutional neural network MobileNetV2, and the recognition result of the vehicle load crossing the bridge is obtained, as shown in Figure 6. As can be seen from Figure 6, there are five vehicles passing through the bridge during this period. In addition, it only takes 0.1s to identify the vehicles crossing the bridge, which is extremely fast and has high real-time performance.
在一个具体的实施例中，计算过桥车辆荷载下大跨拱桥的理论极限响应过程如图2所示，S3包括：In a specific embodiment, the process of calculating the theoretical limit response of a long-span arch bridge under the load of a vehicle passing through the bridge is shown in FIG2 , and S3 includes:
S301：考虑环境温度变化、拱肋损伤影响，基于大跨拱桥真实拱轴线形，构建大跨拱桥服役条件下的几何非线性控制微分方程；S301: Considering the influence of ambient temperature change and arch rib damage, based on the real arch axis shape of the long-span arch bridge, the geometric nonlinear control differential equation of the long-span arch bridge under service conditions is constructed;
S302：根据几何非线性控制微分方程，结合样条函数理论和Newton-Raphson法，计算各节点处拱肋竖向位移ω、水平位移δ、截面轴力N′、截面弯矩M′；S302: According to the geometric nonlinear control differential equation, combined with the spline function theory and the Newton-Raphson method, the vertical displacement ω, horizontal displacement δ, section axial force N′, and section bending moment M′ of the arch rib at each node are calculated;
S303：计算各节点处截面形心应变和曲率；S303: Calculate the centroid strain and curvature of the cross section at each node;
S304：根据弯矩和曲率的关系，以及轴力和形心应变的关系，迭代计算各节点处的截面真实弯矩和截面真实轴力；S304: Iteratively calculate the true bending moment and true axial force of the section at each node according to the relationship between the bending moment and the curvature, and the relationship between the axial force and the centroid strain;
S305：根据各节点处截面真实弯矩、截面真实轴力，计算各节点处截面抗弯刚度、抗压刚度；S305: Calculate the bending stiffness and compressive stiffness of the cross section at each node according to the true bending moment and true axial force of the cross section at each node;
S306：更新各节点处截面抗弯刚度和抗压刚度，重复步骤S301-S305，直到各节点处截面满足内力平衡条件；所述内力平衡条件为：更新截面抗弯刚度和抗压刚度前，所述几何非线性控制微分方程计算得到的截面轴力和截面弯矩计算值，与更新后的截面轴力和截面弯矩计算值相等；S306: updating the bending stiffness and compressive stiffness of the cross section at each node, and repeating steps S301-S305 until the cross section at each node satisfies the internal force balance condition; the internal force balance condition is: before updating the bending stiffness and compressive stiffness of the cross section, the calculated values of the cross section axial force and cross section bending moment calculated by the geometric nonlinear control differential equation are equal to the updated calculated values of the cross section axial force and cross section bending moment;
S307：判断各节点处截面是否发生破坏，若未发生破坏，则施加下一荷载增量步，重复步骤S301-S306；若发生破坏，则输出得到大跨拱桥的极限响应。S307: Determine whether the cross section at each node is damaged. If not, apply the next load increment and repeat steps S301-S306. If damage occurs, output the ultimate response of the long-span arch bridge.
在一个具体的实施例中，S302中几何非线性控制微分方程为：In a specific embodiment, the geometric nonlinear control differential equation in S302 is:
式中，ω和δ分别为拱的竖向位移和水平位移，MA和MB分别为左、右拱脚弯矩，H代表拱脚水平推力，VA为左拱脚竖向反力；以左拱脚为原点建立直角坐标系，x为拱的横坐标；系数C1、C2、C3、C4、C5满足如下关系：Where ω and δ are the vertical displacement and horizontal displacement of the arch respectively,MA andMB are the bending moments of the left and right arch feet respectively, H represents the horizontal thrust of the arch foot, andVA is the vertical reaction force of the left arch foot. A rectangular coordinate system is established with the left arch foot as the origin, and x is the horizontal coordinate of the arch. The coefficientsC1 ,C2 ,C3 ,C4 , andC5 satisfy the following relationship:
式中，y代表大跨拱桥实际拱轴方程，根据实测的拱轴线性拟合得到，y′代表y的一阶导数，y″代表y的二阶导数，EI和EA分别为截面抗弯刚度和抗压刚度，ξ＝x/l，l代表拱桥计算跨径，Mx表示荷载作用下相应简支曲梁任意截面弯矩，t为截面上下缘升温之和，Δt为截面上下缘的温差，α为材料的线膨胀系数，d为截面高度。几何非线性控制微分方程是针对整个大桥的，可以计算桥梁任意节点的竖向位移和水平位移、截面轴力和截面弯矩。Where y represents the actual arch axis equation of the long-span arch bridge, which is obtained by linear fitting of the measured arch axis. y′ represents the first-order derivative of y, y″ represents the second-order derivative of y, EI and EA are the section bending stiffness and compressive stiffness, respectively. ξ＝x/l, l represents the calculated span of the arch bridge,Mx represents the bending moment of any section of the corresponding simply supported curved beam under load, t is the sum of the temperature rise of the upper and lower edges of the section, Δt is the temperature difference between the upper and lower edges of the section, α is the linear expansion coefficient of the material, and d is the section height. The geometrically nonlinear governing differential equation is for the entire bridge, and can calculate the vertical and horizontal displacements, section axial forces, and section bending moments of any node of the bridge.
在一个具体的实施例中，S303中计算公式如下：In a specific embodiment, the calculation formula in S303 is as follows:
式中，si和s′i分别代表第i个离散节段变形前后的弧长，ε0为第i个节点处截面形心应变，为第i个节点处截面曲率，ωi和δi分别为第i个节点的竖向和水平位移，ω′为ωi的一阶导数，ω″为的二阶导数，xi为第i个节点处水平坐标，yi为第i个节点处竖向坐标。Wheresi ands′i represent the arc lengths of the ith discrete segment before and after deformation,ε0 is the centroid strain of the cross section at the ith node, is the section curvature at the i-th node, ωi and δi are the vertical and horizontal displacements of the i-th node, ω′ is the first-order derivative of ωi , ω″ is the second-order derivative of ,xi is the horizontal coordinate at the i-th node, andyi is the vertical coordinate at the i-th node.
在一个具体的实施例中，S305中截面真实弯矩M的计算公式如下：In a specific embodiment, the calculation formula of the cross-section true bending moment M in S305 is as follows:
式中，n＝N0/Nu代表轴压比，Nu为截面的轴压极限轴力，B4(n)、B5(n)为折线斜率，通过纤维模型法确定，Mcr(n)为截面开裂弯矩，分别是截面开裂曲率和极限曲率；Where n = N0 /Nu represents the axial compression ratio,Nu is the axial compression limit axial force of the section, B4 (n) and B5 (n) are the broken line slopes determined by the fiber model method,Mcr (n) is the section cracking moment, are the cross-section cracking curvature and limiting curvature respectively;
截面真实轴力N的计算公式如下：The calculation formula of the true axial force N of the section is as follows:
N＝P1(m)ε2+P2(m)ε+P3(m),M＜Mu；N＝P1 (m)ε2 +P2 (m)ε+P3 (m), M＜Mu ;
式中，m＝M/Mu代表弯矩比，Mu为截面的纯弯极限弯矩，P1(m)、P2(m)、P3(m)分别代表二次抛物线的系数，通过纤维模型法确定，ε为截面形心应变；Where, m = M/Mu represents the moment ratio,Mu is the pure bending limit moment of the section, P1 (m), P2 (m), and P3 (m) represent the coefficients of the quadratic parabola, respectively, which are determined by the fiber model method, and ε is the centroid strain of the section;
迭代计算时，首先令N0＝N′，N′为根据几何非线性控制微分方程计算得到的截面轴力，然后根据N0计算M值，并基于M值计算N值，直至N＝N0。During the iterative calculation, firstly, N0 =N′, where N′ is the cross-sectional axial force calculated according to the geometric nonlinear governing differential equation, and then the M value is calculated according to N0 , and the N value is calculated based on the M value until N=N0 .
在一个具体的实施例中，S307中根据下式判断截面是否发生破坏：In a specific embodiment, in S307, whether the cross section is damaged is determined according to the following formula:
f(n,m)-1＝0；f(n,m)-1＝0;
式中，n和m分别代表截面的轴压比与弯矩比，f(n,m)为截面的广义屈服函数，广义屈服函数根据不同拱圈截面通过数值计算确定。Where n and m represent the axial compression ratio and bending moment ratio of the section respectively, and f(n,m) is the generalized yield function of the section. The generalized yield function is determined by numerical calculation according to different arch ring sections.
在一个具体的实施例中，通过实测真实响应与理论极限响应的包络对比，评估大跨拱桥的服役状态，若根据实测真实响的平均值与理论极限响应的平均值的比值小于阈值，则说明桥梁无明显的状态退化，仍处于安全运行状态。In a specific embodiment, the service status of a long-span arch bridge is evaluated by comparing the envelope of the measured real response with the theoretical limit response. If the ratio of the average value of the measured real response to the average value of the theoretical limit response is less than a threshold, it means that the bridge has no obvious state degradation and is still in a safe operating state.
实测真实响应与理论极限响应的包络对比如图7所示，从图7中可以看出，实测真实响应远低于理论极限响应，因此桥梁目前处于安全运行状态。由于整个评估流程中车辆荷载识别和极限响应计算仅需极少的时间就可以完成，因此本发明公开的方法能够实现大跨拱桥服役状态的快速评估，可为大跨拱桥得监测预警提供重要的技术支持。The envelope comparison of the measured real response and the theoretical limit response is shown in Figure 7. It can be seen from Figure 7 that the measured real response is much lower than the theoretical limit response, so the bridge is currently in a safe operating state. Since the vehicle load identification and limit response calculation in the entire evaluation process only take a very short time to complete, the method disclosed in the present invention can realize the rapid evaluation of the service status of the long-span arch bridge, and can provide important technical support for the monitoring and early warning of the long-span arch bridge.
本发明实施例还公开了一种大跨拱桥服役状态评估系统，包括：依次数据连接的真实响应获取模块、车辆载荷识别模块、理论极限计算模块、评估模块，且真实响应获取模块还与评估模块数据连接；The embodiment of the present invention also discloses a long-span arch bridge service status assessment system, comprising: a real response acquisition module, a vehicle load identification module, a theoretical limit calculation module, and an assessment module which are sequentially data-connected, and the real response acquisition module is also data-connected to the assessment module;
真实响应获取模块：获取运行条件下过桥车辆荷载的实测真实响应；Real response acquisition module: obtains the measured real response of the vehicle load over the bridge under operating conditions;
车辆载荷识别模块：通过荷载识别算法，建立过桥车辆荷载与大跨拱桥结构响应的映射关系，根据所述实测真实响应，实时识别过桥车辆荷载；Vehicle load identification module: through the load identification algorithm, a mapping relationship between the vehicle load on the bridge and the structural response of the long-span arch bridge is established, and the vehicle load on the bridge is identified in real time according to the measured real response;
理论极限计算模块：根据大跨拱桥实际拱轴线形，计算过桥车辆荷载下大跨拱桥的理论极限响应；Theoretical limit calculation module: Calculate the theoretical limit response of a long-span arch bridge under the load of vehicles passing through the bridge according to the actual arch axis shape of the long-span arch bridge;
评估模块：通过所述实测真实响应与所述理论极限响应的包络对比，评估大跨拱桥的服役状态。Evaluation module: evaluates the service status of the long-span arch bridge by comparing the envelope of the measured real response with the theoretical limit response.
本说明书中各个实施例采用递进的方式描述，每个实施例重点说明的都是与其他实施例的不同之处，各个实施例之间相同相似部分互相参见即可。对于实施例公开的装置而言，由于其与实施例公开的方法相对应，所以描述的比较简单，相关之处参见方法部分说明即可。In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.
对所公开的实施例的上述说明，使本领域专业技术人员能够实现或使用本发明。对这些实施例的多种修改对本领域的专业技术人员来说将是显而易见的，本文中所定义的一般原理可以在不脱离本发明的精神或范围的情况下，在其它实施例中实现。因此，本发明将不会被限制于本文所示的这些实施例，而是要符合与本文所公开的原理和新颖特点相一致的最宽的范围。The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.
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