Experimental tests on slip factor in friction joints: Comparison between european and American standards

Friction 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 procedure

Structural behaviour of masonry arch with no-horizontal springing settlement

This paper presents a calculation procedure for assessing the structural integrity of a masonry arch with non-horizontal springing settlement. By applying the Principle of Virtual Work (PVW) to the deformed arch system, the procedure proposed herein details the reaction forces and thrust lines for each step of imposed settlement of the support. The procedure can also be used estimate the final displacement that causes complete failure of arch structural capacity. The results of the analysis procedure were compared against those obtained by experimental testing so as to validate the proposed calculation metho

Influence of the arch thickness discontinuities on the seismic capacity of masonry bridges

Arch bridges still represent a large component of rail and road infrastructure on the European continent. Their operation and safety maintenance is one of the main aims of the rail and road infrastructure managers. Maintenance strategies and bridge management begin with the structural assessment phase. The structural behaviour of masonry arches is very complex to evaluate and it is influenced from various parameters (geometric, mechanical and environmental). In this paper, the structural behaviour of arches with discontinuous thickness is analysed. In particular, the variation of the horizontal load resistance is evaluated by varying the ratio of the extension of the arch length with a smaller thickness and the ratio between the largest and the smaller thickness

Municipal expected annual loss as an indicator to develop seismic risk maps in Italy

This work presents a risk-targeted indicator called Municipal Expected Annual Loss (MEAL) for a quantitative estimation of the seismic risk at territorial level. With MEAL, it is possible to calculate the impact of earthquakes in terms of direct losses, taking account of a wide set of earthquake scenarios on the built environment at municipal level. MEAL is, therefore, able to summarize scenario loss values of each municipality, and define in such a way a risk-targeted metric that can clearly be understood also by different stakeholders dealing with seismic risk management, mitigation, and transfer. The use of MEAL to map seismic risk for the Italian residential building stock is herein presented as a case-study, leading to the development of several maps able to depict seismic risk at different territorial scale levels

Fatigue Damage Estimation in Existing Railway Steel Bridges by Detailed Loading History Analysis

Fatigue life estimation of metal historical bridges is a key issue for managing cost-effective decisions regarding rehabilitation or replacement of existing infrastructure. Because of increasing service loads and speeds, this type of assessment method is becoming relevant. Hence there is a need to estimate how long these structures could remain in service. In this paper a method to estimate fatigue damage in existing steel railway bridges by detailed loading history analysis is presented. The procedure is based on the assumption that failure probability is a function of the number of predicted future trains and the probability of failure is related to the probability of reaching the critical crack length

Rigid-block analysis of archeological elements retrofitted with external post-tensioning system

Abstract In Europe, many archeological sites require continuous maintenance interventions capable of preserving the cultural value of this type of heritage. To this end, particular attention must be paid to ruins, the remains of larger portions and archeological artifacts. These elements, generally made of ancient stone masonry materials are vulnerable to external action such as are earthquakes, differential settlements, degradation, etc.. In order to reduce their structural vulnerability, repair interventions are usually required using repair techniques that preserve the artistic and aesthetical values of the archeological element. One of these techniques is the use of external post-tensioning system through pre-stressed cables. In this contribution, some examples of the application of post-tensioning to an archeological element are presented. The application of rigid-block analysis to archeological elements (retrofitted with external post-tensioning system) is developed and discussed

Fatigue strength of corroded bolted connection

This note summarizes some recent investigation results on the behavior of corroded steel bolted joints under uniaxial fatigue loading. Fatigue test specimens, were made up using S355 structural steel plates joined together with preloaded M12 bolts of class 10.9 with a geometry that corresponds to the Δσ = 112 MPa EC3 detail category. The accelerated corrosion process was accomplished using an electrolyte consisting of an aqueous 5% NaCl solution whereby the specimens were treated. In particular, during the corrosion process specimens were repeatedly immersed for 2 minutes in the electrolyte and then removed keeping them 60 minutes long in free air at 35 °C. An atmospheric corrosion in marine-industrial environment is wellrepresented through corrosion test. Fatigue loading tests and surface morphology measurement of uncorroded and corroded specimens were performed and the results were compared