Procedia Structural Integrity最新文献

The Italian Guidelines for special inspections of post-tensioned concrete bridges: review and case study 意大利后张法混凝土桥梁特殊检查准则：回顾与案例研究

Procedia Structural Integrity

Pub Date : 2024-01-01 DOI: 10.1016/j.prostr.2024.09.045

Eleonora Bruschi , Dalila Rossi , Carlo Pettorruso , Luca Zoccolini , Virginio Quaglini

Post-tensioned (PT) concrete bridges are structural systems characterized by intrinsic fragility. The assessment of their health condition is very difficult due to their nature, which prevents the detection of degradation in PT elements through conventional investigation methods and/or visual inspections. For this reason, the Italian Guidelines for the maintenance of existing bridges envisage special inspections to assess the condition of the post-tensioning system. According to the dedicated Guideline, the special inspection procedure consists of four steps. First there is Step O, which identifies the number and location of PT samples to be investigated based on the historical•critical review of available documentation and the visible defects in the post-tensioned members. Then, in Step 1 a preliminary analysis of the identified PT elements is performed, identifying the presence and location of active defects and grout voids, as well as the probability of corrosion of the reinforcement through non-destructive tests. In Step 2, the analysis of defects becomes more accurate, determining the probability of corrosion and estimating the level of stress in the concrete and in post-tensioned cables through locally destructive tests. Step 3 is applied if the outcome of Step 2 is uncertain and involves the experimental analysis of the overall structural response of the bridge. Eventually, in case the presence of damaged PT elements is confirmed, a load assessment of the structure is performed. The objective of this study is to evaluate the effectiveness of the investigation method proposed by the Italian Guidelines, highlighting its strengths and potential weaknesses. The procedure is applied to the Dora Riparia River Bridge, located in Avigliana (Turin) on provincial road SP197. The bridge consists of seven spans, 21.4 m long, and is characterized by a simply supported static layout; each span has four post-tensioned I-shape beams and four post-tensioned diaphragms.

后张法（PT）混凝土桥梁是一种具有内在脆弱性的结构系统。由于其本身的性质，很难通过传统的调查方法和/或目视检查来发现 PT 构件的退化情况，因此很难对其健康状况进行评估。因此，意大利的《现有桥梁维护指南》规定进行特殊检查，以评估后张法系统的状况。根据专门的准则，特殊检查程序包括四个步骤。首先是步骤 O，根据对现有文件和后张法构件可见缺陷的历史关键审查，确定需要调查的 PT 样品的数量和位置。然后，在步骤 1 中对已确定的 PT 构件进行初步分析，通过无损检测确定存在的活动缺陷和灌浆空洞及其位置，以及钢筋锈蚀的可能性。在第二步中，对缺陷的分析变得更加精确，通过局部破坏性试验确定锈蚀的概率并估算混凝土和后张拉索的应力水平。如果步骤 2 的结果不确定，则采用步骤 3，对桥梁的整体结构响应进行实验分析。最后，如果确认存在受损的 PT 构件，则对结构进行荷载评估。本研究的目的是评估《意大利指南》所建议的调查方法的有效性，突出其优点和潜在的不足。该程序适用于位于阿维利亚纳（都灵）省道 SP197 上的 Dora Riparia 河大桥。该桥由七跨组成，长 21.4 米，采用简支撑静态布局；每跨有四根后张法工字梁和四根后张法横隔梁。

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引用次数: 0

The IRRADIA research project for the advanced management of infrastructures IRRADIA 基础设施高级管理研究项目

Procedia Structural Integrity

Pub Date : 2024-01-01 DOI: 10.1016/j.prostr.2024.09.013

Alberto Brajon , Eleonora Cesolini , Davide Bernardini , Franco Ciminelli , Egidio Lofrano , Achille Paolone

AISICO and ‘Sapienza’ University of Rome are working on the project IRRADIA, a research program aiming to investigate the use of Artificial Intelligence for the structural assessment of railway and road infrastructures. The starting point is the BRIGHT method (BRIdGes Health Testing method, patented by AISICO), already applied on a large data set of information, and essentially based on the automatic detection of damages on structural elements of bridges and viaducts. The results carried out on 80 railway bridges provide new ideas to the sector of monitoring and control of existing infrastructures in terms of automatization. Then, the BRIGHT method, built on the railway specifications described by DOMUS, has been recently expanded to meet the requirements of the 2022 Italian Guidelines for existing road bridges and viaducts (DM 204, 1/07/2022). These require to fulfill several defect sheets for each structural element (e.g., beams, transversal beams, slabs, piers, abutments, supports, and so on), with a proper evaluation, for each defect, of type, extension and intensity. It follows that the damage evaluation requires usually a large number of operations with a high level of repetitiveness. Therefore, the use of AI techniques is a promising tool for the near future, to acquire and collect the images with unmanned aerial vehicle, from one hand, and to fulfill the defect sheets, from the other one, reducing time and cost. In this framework, one of the main goals of the cited IRRADIA research project is the investigation of the results obtained with the BRIGHT method extended to 2022 Italian Guidelines, that is, to road infrastructures. In this contribution the first results obtained on two bridges, the first in reinforced concrete and the second with a masonry structure, are presented and discussed.

AISICO 和罗马 "萨皮恩扎 "大学正在开展 IRRADIA 项目，该研究项目旨在调查人工智能在铁路和公路基础设施结构评估中的应用。该项目的出发点是 BRIGHT 方法（BRIdGes Health Testing method，由 AISICO 获得专利），该方法已应用于大量的信息数据集，主要基于自动检测桥梁和高架桥结构元素的损坏情况。在 80 座铁路桥梁上取得的成果为监测和控制现有基础设施的自动化提供了新思路。BRIGHT 方法以 DOMUS 所描述的铁路规范为基础，最近又进行了扩展，以满足 2022 年意大利既有公路桥梁和高架桥指南（DM 204，1/07/2022）的要求。这些要求为每个结构元素（如梁、横梁、板、桥墩、桥台、支撑等）提供多个缺陷表，并对每个缺陷的类型、扩展和强度进行适当评估。由此可见，损伤评估通常需要大量的重复性操作。因此，在不久的将来，使用人工智能技术是一种很有前途的工具，一方面可以利用无人驾驶飞行器获取和收集图像，另一方面可以完成缺陷表的制作，从而减少时间和成本。在此框架下，IRRADIA 研究项目的主要目标之一是研究 BRIGHT 方法在 2022 年意大利准则（即道路基础设施）中取得的成果。本文介绍并讨论了在两座桥梁上取得的初步成果，第一座是钢筋混凝土桥梁，第二座是砌体结构桥梁。

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引用次数: 0

Health assessment of road bridges with Gerber saddles: non-linear planar models 使用格柏鞍座的公路桥梁健康评估：非线性平面模型

Procedia Structural Integrity

Pub Date : 2024-01-01 DOI: 10.1016/j.prostr.2024.09.056

Pasquale Fusco , Davide Bernardini , Gianfranco De Matteis , Egidio Lofrano , Achille Paolone , Mattia Zizi

A correct assessment of the structural behavior and performance of deteriorated structures is crucial both for a proper planning of maintenance works and for a correct design of new structures in aggressive environments. The aim of this work is to investigate the response of Gerber saddles to the variation of the two main parameters representing typical damaged scenarios: the concrete cover and the diameter of the steel reinforcements. The analyses are conducted through Finite Element two-dimensional non-linear models based on the compatible stress field; the results are compared with the relevant ‘Strut and Tie’ models. At first, parametric analyses are carried out, in order to evaluate the sensitivity of load capacity to the position of steel rebars and to the dimension of concrete cover; this first part of the contribution aims to highlight the importance of an adequate level of knowledge. Then, the contribution focuses on the reduction of saddle capacity due to degradation conditions, referred to both the loss of concrete cover and the corrosion of reinforcing bars. The analyses closes with a comparison among the results provided by the two-dimensional investigations and the ones provided by the relevant ‘Strut and Tie’ models.

正确评估老化结构的结构行为和性能，对于合理规划维护工程和正确设计侵蚀环境中的新结构都至关重要。这项工作的目的是研究格柏鞍座对代表典型受损情况的两个主要参数变化的响应：混凝土覆盖层和钢筋直径。分析是通过基于兼容应力场的有限元二维非线性模型进行的；分析结果与相关的 "支柱和拉杆 "模型进行了比较。首先，进行了参数分析，以评估承载能力对钢筋位置和混凝土保护层尺寸的敏感性。然后，文章重点讨论了由于退化条件导致的鞍座承载力降低问题，包括混凝土覆盖层的损失和钢筋的腐蚀。分析最后对二维研究结果和相关 "支柱和拉杆 "模型的结果进行了比较。

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引用次数: 0

Interoperability between structural and geotechnical analysis for the study of safety in existing bridges 结构分析和岩土分析在研究现有桥梁安全方面的互操作性

Procedia Structural Integrity

Pub Date : 2024-01-01 DOI: 10.1016/j.prostr.2024.09.070

Adalgisa Zirpoli , Paolo Sattamino

In recent years, the engineering community has shown a significant increase in interest in the field of soil-structure interaction. This problem is undoubtedly one of the most complex. Despite the exponential increase in computer performance in the last two decades, followed by the continuous development of numerical methods, the interaction between structural analysis programs and geotechnical issues remains limited. Specialized calculation codes for structural engineering and geotechnical engineering often operate independently. The reason for this separation lies in the highly specialized capabilities that a solver designed for geotechnical issues must possess. However, it remains crucial to incorporate the structural element within its geotechnical context, especially in the case of structures that are fully or partially embedded in the ground, such as tunnels, retaining walls, bridge abutments, and so on. There exists a mutual and reciprocal influence of the stress-strain state: the stiffness (and strength) of the foundation determines the response of the structure, which in turn affects the response of the foundation through its own stiffness. In many projects, there is an increasing demand to develop analyses that harness the full potential of both the structural and geotechnical aspects. Hence, there is a clear need to establish a connection between these two computational environments. The proposed solution involves the interaction of two programs: Midas Civil, an essential tool for structural engineers, and Flac 3D, a general-purpose software for geotechnical engineering. As explained further, this interaction is made possible thanks to the flexibility and openness of both software codes. Referring to a real case study of a road bridge with a superstructure consisting of reinforced concrete beams, this paper will illustrate the main challenges, significant steps, and undeniable advantages obtained through this approach.

近年来，工程界对土体与结构相互作用领域的兴趣大增。这个问题无疑是最复杂的问题之一。尽管在过去二十年中计算机性能呈指数级增长，数值方法也随之不断发展，但结构分析程序与岩土工程问题之间的互动仍然有限。结构工程和岩土工程的专业计算代码通常是独立运行的。这种分离的原因在于为岩土工程问题设计的求解器必须具备高度专业化的能力。然而，将结构元素纳入岩土工程范畴仍然至关重要，尤其是对于完全或部分嵌入地下的结构，如隧道、挡土墙、桥台等。应力-应变状态存在着相互和相互影响：地基的刚度（和强度）决定了结构的响应，而结构的响应又反过来通过地基自身的刚度影响地基的响应。在许多项目中，人们越来越需要开发出能够充分利用结构和岩土两方面潜力的分析方法。因此，显然需要在这两个计算环境之间建立联系。建议的解决方案涉及两个程序的交互：Midas Civil 是结构工程师的必备工具，而 Flac 3D 则是岩土工程的通用软件。正如进一步解释的那样，由于这两个软件代码的灵活性和开放性，这种互动成为可能。本文将通过对一座由钢筋混凝土梁组成的上部结构公路桥的实际案例研究，说明这种方法所面临的主要挑战、重要步骤以及无可否认的优势。

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引用次数: 0

Numerical Model of 3D Printed Joint of Wooden Frame 木制框架接头的 3D 打印数值模型

Procedia Structural Integrity

Pub Date : 2024-01-01 DOI: 10.1016/j.prostr.2024.09.007

Petr Lehner , David Juračka , Dominik Gřešica , Martin Krejsa

Regardless of the type of material, 3D printing seems to be an interesting alternative to conventional construction methods. Leaving aside the use of 3D printing systems for concrete or cement composites, the more conventional 3D printing of plastic, metal or other separated materials may also have its hypothetical benefits in the creation of structural joints. For truss structures, such as arch bridges, certain types of joints can be expected that do not always have the same angle between the single-plane load-bearing elements of the structure. In such a case, the use of 3D printing technology for joint fabrication is defensible. In the case of a standard scale and using experience from timber bridges, one would assume that an embedded plate and pin connection would be the appropriate connection form. In contrast, from the point of view of producing smaller physical models, mainly for a deeper understanding of the comparability issues of numerical modelling and experimental testing, it is advantageous to use so-called enveloping timber element connections. The present paper describes the basic process of numerical analysis of a detail of a wooden arch bridge connection made from 3D printed polycarbonate joints.

无论是哪种材料，3D 打印似乎都是传统建筑方法的一种有趣的替代方案。抛开使用 3D 打印系统制造混凝土或水泥复合材料不谈，更传统的塑料、金属或其他分离材料的 3D 打印在制造结构接缝方面也可能有其假设的好处。对于拱桥等桁架结构而言，某些类型的接缝在结构的单面承重元件之间并不总是具有相同的角度。在这种情况下，使用三维打印技术来制作接缝是可行的。在标准比例的情况下，根据木桥的经验，人们会认为嵌入式板销连接是合适的连接形式。相反，从制作小型物理模型的角度来看，主要是为了更深入地了解数值建模和实验测试的可比性问题，使用所谓的包络木构件连接是有优势的。本文介绍了对用 3D 打印聚碳酸酯连接件制作的木拱桥连接细节进行数值分析的基本过程。

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引用次数: 0

Understanding the response of masonry arch bridges under different scour scenarios 了解圬工拱桥在不同冲刷情况下的反应

Procedia Structural Integrity

Pub Date : 2024-01-01 DOI: 10.1016/j.prostr.2024.09.061

Fabrizio Scozzese , Enrico Tubaldi , Andrea Dall’Asta

In the last decades, several flood-induced bridge collapses have been registered all over the world, in particular related to local scour phenomenon. Masonry bridges, which constitute the most of the existing infrastructure heritage worldwide, are significantly sensitive to this problem because of their high stiffness and typically shallow foundations. With the aim of helping to understand the response of masonry arch bridges under scour actions, this paper proposes a numerical study on a real case study. A 3D finite element model of the bridge is developed in Abaqus accounting for both mechanical and geometrical nonlinearities, then two possible scour scenarios are simulated by following a consolidated procedure proposed in previous works and the damage mechanisms activated at different scour levels are analyzed and discussed.

在过去的几十年里，世界各地发生了多起由洪水引发的桥梁坍塌事故，特别是与局部冲刷现象有关的事故。圬工结构桥梁是全球现有基础设施遗产的主体，由于其刚度高且地基通常较浅，因此对这一问题非常敏感。为了帮助理解圬工拱桥在冲刷作用下的响应，本文对一个实际案例进行了数值研究。在 Abaqus 中建立了该桥的三维有限元模型，考虑到了力学和几何非线性因素，然后按照以前著作中提出的综合程序模拟了两种可能的冲刷情况，并分析和讨论了不同冲刷程度下的损坏机制。

引用次数: 0

Effect of Nozzle Diameter on Tensile and Fracture Behavior of FDM-PLA Samples 喷嘴直径对 FDM-PLA 样品拉伸和断裂行为的影响

Procedia Structural Integrity

Pub Date : 2024-01-01 DOI: 10.1016/j.prostr.2024.06.004

Shadi Salamatian Hosseini , Amir Nabavi-Kivi , Majid R Ayatollahi , Michal Petru

Fused Deposition Modeling (FDM) technique is a subcategory of additive manufacturing processes that works by extruding a fine polymeric filament on the heated bed. The current research paper surveys the influence of nozzle diameter as a manufacturing parameter on the mechanical properties and mode I fracture behavior of the FDM-PLA samples. Four different nozzle diameters of 0.4, 0.6, 0.8, and 1 mm with two raster configurations of 0/90° and 45/-45° were considered for printing the dog-bone and Semi-Circular Bending (SCB) samples. Also, to evaluate the fracture resistance of FDM-PLA pre-cracked samples, the critical value of J-integral (Jc) was used and calculated through a finite element analysis. The obtained results indicated that the raster angle of 45/-45° resulted in higher mechanical properties compared to 0/90° one, also, the 1 mm nozzle diameter presented a better performance from a mechanical property point of view. The SCB sample printed through the 1 mm nozzle diameter and 45/-45° raster orientation had the highest value of Jc (10400 J/m²). Besides, the crack extension paths were monitored and discussed comprehensively.

熔融沉积建模（FDM）技术是增材制造工艺的一个子类，其工作原理是在加热的床面上挤出细小的聚合物丝。本研究论文探讨了作为制造参数的喷嘴直径对 FDM-PLA 样品的机械性能和模式 I 断裂行为的影响。考虑了 0.4、0.6、0.8 和 1 毫米四种不同的喷嘴直径，以及 0/90° 和 45/-45° 两种光栅配置，用于打印狗骨和半圆弯曲 (SCB) 样品。此外，为了评估 FDM-PLA 预裂纹样品的抗断裂性，使用了 J 积分（Jc）临界值，并通过有限元分析进行了计算。结果表明，与 0/90° 的光栅角相比，45/-45° 的光栅角具有更高的机械性能，而且从机械性能的角度来看，喷嘴直径为 1 毫米的光栅角具有更好的性能。采用 1 毫米喷嘴直径和 45/-45° 光栅方向印刷的 SCB 样品具有最高的 Jc 值（10400 J/m2）。此外，还对裂纹扩展路径进行了全面监测和讨论。

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引用次数: 0

Effects of Print Orientation on Mode-I Fracture Toughness of Additively Manufactured PLA: Simulation by XFEM 打印方向对增材制造聚乳酸 Mode-I 断裂韧性的影响：XFEM 仿真

Procedia Structural Integrity

Pub Date : 2024-01-01 DOI: 10.1016/j.prostr.2024.06.030

Bahman Paygozar, Recep M. Gorguluarslan

In engineering applications, considering the growing utilization of Polylactic acid (PLA) material manufactured through material extrusion (MEX) additive manufacturing techniques, it becomes imperative to predict its fracture behavior to assess damage thoroughly under various loading scenarios. As an initial step, this study focuses on determining the Mode-I fracture toughness of the PLA material manufactured by MEX in three different print orientations through a three-point (3P) bending fracture test. The raster angle utilized to fabricate the single-edge notch bending (SENB) specimens was chosen as ±45°. Three different print orientations were used to investigate the effects of printing direction (i.e., horizontal, lateral, and vertical) on the fracture properties. The fracture properties were extracted per the standard ASTM D5045-14 on the specimens fabricated in three different print orientations. The values of Mode-I fracture toughness of PLA were respectively obtained as 4.22, 4.18, and 3.56 MPa/m with horizontal, lateral, and vertical print orientation. Then, corresponding fracture energy values were calculated for numerical investigations. A commercial finite element package was utilized to employ the extracted values into the extended finite element method (XFEM) and investigate the crack propagation in the specimens. It was found that the numerical analyses well simulated the crack propagation and peak load (damage initiation point) experienced in the SENB specimens tested under 3P bending loading.

在工程应用中，考虑到通过材料挤压（MEX）增材制造技术制造的聚乳酸（PLA）材料的使用率越来越高，预测其断裂行为以彻底评估各种加载情况下的损伤变得势在必行。作为第一步，本研究的重点是通过三点（3P）弯曲断裂测试，确定通过 MEX 制造的聚乳酸材料在三种不同打印方向上的 Mode-I 断裂韧性。用于制作单边缺口弯曲（SENB）试样的光栅角度选择为±45°。三种不同的印刷方向用于研究印刷方向（即水平、横向和垂直）对断裂特性的影响。根据 ASTM D5045-14 标准提取了三种不同印刷方向试样的断裂性能。在水平、横向和垂直印刷方向上，聚乳酸的模式 I 断裂韧性值分别为 4.22、4.18 和 3.56 MPa/m。然后，计算出相应的断裂能值，用于数值研究。利用商业有限元软件包将提取的数值应用到扩展有限元法（XFEM）中，并研究试样中的裂纹扩展。结果发现，数值分析很好地模拟了在 3P 弯曲加载下测试的 SENB 试样的裂纹扩展和峰值载荷（损伤起始点）。

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引用次数: 0

Impact of Element Layout and Notching Technique on the Fracture Toughness of FFF-Processed Thermoplastics 元件布局和切口技术对 FFF 加工热塑性塑料断裂韧性的影响

Procedia Structural Integrity

Pub Date : 2024-01-01 DOI: 10.1016/j.prostr.2024.06.020

Albert E. Patterson , Charul Chadha , Iwona M. Jasiuk , James T. Allison

This work explores the effects of notching method and element layout on the fracture loading properties of thermoplastic materials processed using fused filament fabrication (FFF). Three common thermoplastic materials were used (acrylonitrile butadiene styrene, polylatide, and polycarbonate). Four different notching methods were used, with printed and machined notches and with and without pre-cracking on ASTM D5045 compact tension specimens (n = 36). It was concluded that the notching method has a statistically significant impact on the sample preparation and that pre-cracking is necessary in all cases. Using this information to prepare specimens, a designed experiment using four different element layout strategies and two different nozzle sizes was completed with a total of 72 tests. The layout pattern was shown to have a very strong effect on the maximum fracture load, with the nozzle size showing a smaller but still statistically significant impact. With the exception of one layout using polycarbonate with likely design-driven printing defects, the results were very consistent through several replications. The results of this study are useful for making design decisions with FFF-processed materials, for better understanding the impact of the process design, and for working toward standardized printing and testing methods for additive manufacturing.

这项研究探讨了切口方法和元件布局对使用熔融长丝制造（FFF）工艺加工的热塑性材料断裂加载性能的影响。研究使用了三种常见的热塑性材料（丙烯腈-丁二烯-苯乙烯、聚酰亚胺和聚碳酸酯）。在 ASTM D5045 紧凑型拉伸试样（n = 36）上使用了四种不同的切口方法，包括印刷切口和机加工切口，以及预裂和不预裂。得出的结论是，切口方法对试样制备有显著的统计学影响，并且在所有情况下都需要预裂纹。利用这些信息制备试样，使用四种不同的元件布局策略和两种不同的喷嘴尺寸完成了设计实验，共进行了 72 次测试。实验结果表明，布局模式对最大断裂载荷的影响非常大，喷嘴尺寸的影响较小，但在统计学上仍有显著影响。除了一个使用聚碳酸酯的布局可能存在设计驱动的印刷缺陷外，多次重复试验的结果都非常一致。这项研究的结果有助于使用 FFF 加工材料做出设计决策，有助于更好地理解工艺设计的影响，也有助于为增材制造制定标准化的打印和测试方法。

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引用次数: 0

Experimental and analytical investigation on the evaluation of residual stresses in prestressed concrete girders 预应力混凝土大梁残余应力评估的实验和分析研究

Procedia Structural Integrity

Pub Date : 2024-01-01 DOI: 10.1016/j.prostr.2024.09.051

Giulia Rossini , Matteo Lamberti , Stefano G. Mantelli , Fausto Minelli , Giovanni Plizzari

Since the strength of prestressed reinforced concrete (PRC) structures, particularly under shear, substantially depends on the effective residual prestressing force, the evaluation of residual stresses in prestressed concrete structures is currently a target of importance. Three semi-destructive techniques were used on the 4 PRC full scale: core trepanning, saw-cut at intrados, and blunt pyramidal specimen for in-situ prestressing evaluation based on tension release. Furthermore, a novel method, resembling parallel saw cuts at the intrados but applied to the web, was introduced and examined. Among the tested techniques, this latter approach demonstrated the highest reliability, and both 2D and 3D finite element models were developed and extensively discussed to support the findings.

由于预应力钢筋混凝土（PRC）结构的强度（尤其是剪切强度）在很大程度上取决于有效的残余预应力，因此评估预应力混凝土结构中的残余应力是当前的一个重要目标。我们在 4 层预应力混凝土结构中采用了三种半破坏性技术：取芯、内径锯切和钝金字塔试件，用于基于张力释放的原位预应力评估。此外，还引入并研究了一种新方法，类似于在内侧平行锯切，但适用于腹板。在测试过的技术中，后一种方法显示出最高的可靠性，同时还开发了二维和三维有限元模型，并对其进行了广泛讨论，以支持测试结果。

引用次数: 0