1,721,118 research outputs found
Horizontal capacity of single-span masonry bridges with intrados FRCM strengthening
No full textThe strengthening of masonry arch bridges, which account for a significant portion of the railway and road bridges in the world's infrastructure network, is a pressing need for the operators of such networks, and even more so in the seismic areas. As any interruptions to road and especially rail traffic are particularly costly, and consequently the most suitable solution involves the design of a strengthening system applied to the intrados of the masonry arch bridge. However, in these circumstances a more compatible and reversible solution compared to traditional strengthening techniques or FRP (Fiber Reinforced Polymer) systems involves the use of FRCM (Fiber Reinforced Cementitious Matrix). This work thus examines the effectiveness of FRCM strengthening on the intrados of masonry arch bridges, taking into account the actual geometric relationships that characterise the arches of bridges and considering the effect of Coulomb friction. The results obtained using lower bound limit analysis highlight the optimal conditions for the use of this strengthening, and the situations in which, due to the actual geometry of the bridges and the friction coefficient value, the use of this strengthening system would not be recommended
Structural response of cable-stayed bridge subjected to blast load
No full textThe recent increase number of terrorist attacks have accrued the vigilance from defense and securities organization of many countries. These entities collaborating with scientists allows providing a better insight into the structural performance of existing buildings subjected to pre-planned attacks. On the other hand, the explosive weapon is the most used methodology by the terrorists since they aimed to reach a consequent loss or damages. In this paper, the structural performance of a generic cable-stayed bridge under blast loading is assessed throughout an extensive numerical analysis. Firstly, a though non-linear analysis is performed to under the ultimate capacity of a generic cable-stayed bridge, then it was possible to simulate the damage induced by the dynamic effect of a high impact action and finally considering different magnitudes of impact load, the failure state of the bridge is highlighted
Collapse mechanisms of masonry buttressed arch with settled support
No full textThis contribute analyses the collapse mechanisms of a circular masonry arch supported on rectangular slender abutments when subjected to an imposed settlement of one support in addition to self-weight, using the principle of virtual work and thrust line analysis. Depending on the angle of settlement and the slenderness of the arch and the abutments, the study identifies the main hinging failure mechanisms where the hinge configurations depend mainly on the angle of the settlement and the slenderness of the arch. An extensive analysis shows the different possible collapse mechanisms of masonry buttressed arches with different type of support settlements
Effect of blast load on the structural integrity of steel arch bridge slab
No full textIn order to know the safety margins and the critical zone of an important infrastructure such as a bridge, the response of the construction typology to extreme forces must be investigated. In this sense, in the literature, few numerical and experimental data are available concerning the response of steel bridges under explosive loads. The purpose of this work is to develop a coherent model, using the finite element analysis method, to verify the behaviour of such a structure and to focus on the collapse mechanism. As a case study, a typical network arch bridge was defined and meshed. Information about stresses, strains and displacement were collected as a function of the position and intensity of the slab damage. Finally, some useful observations were collected regarding the slab response, damage mechanisms and the role of the concrete class
Lateral Stability of Network Arch Bridges
No full textNetwork arch bridges are arch bridges where hangers intersect each other at least twice. Although these innovative bridges present several advantages in terms of cost and structural performance with respect to the conventional tied-arch bridges, they remain vulnerable under certain loading condition. Indeed, due to the large compressive force that may arise in steel arches of the bridge under service, they are prone to deflect out of his plane resulting in the degradation of the aesthetic aspect often praised of bridges of this type and later its service disablement. For this reason, the lateral behaviour of such kind of bridges should be investigated carefully. In this study, lateral structural response of network arch bridges against traffic loads has been analyzed through extensive non-linear analyses. Firstly, a calibration is useful to validate the numerical model. Then, initial geometric imperfections are assigned to the arch member before the analysis in order to take into consideration defects from the manufacturing process. Finally, non-linear analyses are performed on a full 3D numerical model to capture the behaviour of the arch bridge. The results showed that the lateral displacement of the arch member increase with the increase of the traffic loads up to a certain value. In addition, it is observed that the lateral arch’s bracing changes the development of plastic hinges in the arch
Seismic capacity of masonry arches with irregular abutments and arch thickness
No full textThe simplest structural analysis for assessing the seismic capacity of a masonry arch is limit analysis. In fact, assuming an equivalent static seismic load, this method can be used to determine the lateral acceleration leading to the collapse mechanism. In this work, applying an analytical procedure, extensive parametric analysis was carried out to describe the seismic capacity of masonry arch structures with irregular geometry. In particular, arches with different abutment heights and discontinuous thicknesses have been examined. The results have been compared against those obtained by finite element analysis and by small scale experimental tests, and a good correlation has been found
Experimental tests on slip factor in friction joints: Comparison between european and American standards
No full textFriction joints are used in steel structures submitted to cyclic loading such as, for example, in steel and composite bridges, in overhead cranes, and in equipment subjected to fatigue. Slip-critical steel joints with preloaded bolts are characterized by high rigidity and good performance against fatigue and vibrational phenomena. The most important parameter for the calculation of the bolt number in a friction connection is the slip factor, depending on the treatment of the plane surfaces inside the joint package. The paper focuses on the slip factor values reported in European and North American Specifications, and in literature references. The differences in experimental methods of slip test and evaluation of them for the mentioned standards are discussed. The results from laboratory tests regarding the assessment of the slip factor related to only sandblasted and sandblasted and coated surfaces are reported. Experimental data are compared with other results from the literature review to find the most influent parameters that control the slip factor in friction joint and differences between the slip tests procedures
3D collapse mechanisms of masonry bridges subjected to horizontal actions
Full text linkA large number of existing masonry arch bridges are still in use in the Italian roadway and railway networks. Most of them were built more than one hundred years ago, designed considering only gravitational loads without any seismic analysis. To keep these works in service, it is necessary to have tools that can describe and predict the structural behavior of the bridge when subjected to extreme actions. For this reason, a threedimensional rigid-block analysis for masonry arch bridges has been developed. In the model, the main structural masonry elements (vault, pier, abutments, spandrel wall) are discretized as an assemblage of rigid blocks, which interact via no-tension contact surface with Coulomb friction. This approach allows reproducing with good accuracy the tri-dimensional collapses mechanisms of some real masonry arch bridges recently collapsed due to extreme events
The masonry buttressed arch on spreading support
No full textThis paper analyses the ultimate states of a circular masonry arch supported on rectangular slender abutments when subjected to an imposed settlement of one support in addition to self-weight, using the principle of virtual work and thrust line analysis. Depending on the angle of settlement and the slenderness of the arch and the abutments, the study identifies the main hinging failure mechanisms where the hinge configurations depend mainly on the angle of the settlement and the slenderness of the arch. In the hypothesis where only radial ruptures are possible, extensive analysis shows the different possible mechanisms on masonry buttressed arches with different type of support settlements. In addition, the analyses show that the masonry buttressed arch is more vulnerable to horizontal displacement than inclined or vertical displacement
Structural performance of a steel cable-stayed bridge under blast loading considering different stay patterns
No full textAccidental or extreme events can induce abnormal loads on structures contributing to a local damage of primary components or to the progressive collapse of the structure. Although hazards, which are usually difficult to be predicted, increase the complexity in the design, the need to determine the consequences on structures of these extreme events remains significant. This study aims to evaluate the damage induced by an accidental load such as blast loading to a cable-stayed bridge. In the first part of the paper, through non-linear dynamic analyses, it was possible to evaluate the structural response of three configurations of cable-stayed bridges, then to figure out the possible immediate and forthcoming damages considering different loading parameters and position. Finally, a displacement-controlled static non-linear pushover analysis of the structure has been performed to evaluate the limit state of the structure for a random position of blast loading and to predict the possible damage state during an accidental event such as blast loading. The results indicate significant effects of the structural configuration of the bridge and stay patterns. The Fan cable-stayed bridge is found to be the most effective among the considered configurations in reducing the dynamic effect induced by the blast loading on the structure. In addition, the deck is found to be less critical in terms of blast load mitigation close to the abutment and the pylon
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