Inertial Effects on Finite Length Pipe Seismic Response

A seismic analysis for soil-pipe interaction which accounts for length and constraining conditions at the ends of a continuous pipe is developed. The Winkler model is used to schematize the soil-structure interaction. The approach is focused on axial strains, since bending strains in a buried pipe due to the wave propagation are typically a second-order effect. Unlike many works, the inertial terms are considered in solving equations. Accurate numerical simulations are carried out to show the influence of pipe length and constraint conditions on the pipe seismic strain. The obtained results are compared with results inferred from other models present in the literature. For free-end pipelines, inertial effects have significant influence only for short length. On the contrary, their influence is always important for pinned pipes. Numerical simulations show that a simple rigid model can be used for free-end pipes, whereas pinned pipes need more accurate models

Inertia force effect on longitudinal vibrations of underground pipelines

The effect of the inertia term on the longitudinal displacements of an underground pipeline is shown for various cases of pipe fastening when a seismic wave propagates along its axis. The problem is solved by analytical and numerical methods. The pipe-soil interaction is assumed to be elastic (shear stress generated in soil is proportional to the relative displacement between the pipe and soil)

Underground main pipeline behaviour under a travelling impulse in the form of a triangle

The article presents an analysis of the dynamic response of an underground main pipeline under the action of a longitudinal wave, propagating in soil along the pipe. It is assumed that the elastic pipe has a finite length. A linear viscoelastic model of the "pipe-soil" system interaction is considered. The influence of a pulse in the form of a triangle on the deformed state of an underground main pipeline is investigated. The article presents a comparative analysis of the results obtained for some values of the coefficients of elastic and viscous interaction, the propagation velocity, and the duration of the pulse. In the case of elastic interaction of the "pipe-soil" system, the reflection of the wave propagating in the underground pipeline on the boundaries of the pipeline when it coincides with the wave propagating in the soil leads to an increase in the maximum deformation of the underground pipeline, the value of deformation can double. The viscosity coefficient of interaction at the pipe-soil system contact leads to the wave front attenuation in the underground pipeline. For soils with the coefficient of viscous interaction higher than 100 kN∙s/m2, this leads to complete attenuation of the bursts at the wave front in the pipeline. The influence of the wave propagation in soil on the deformation values at the wave front was also studied

Earthquake Engineering

The book Earthquake Engineering - From Engineering Seismology to Optimal Seismic Design of Engineering Structures contains fifteen chapters written by researchers and experts in the fields of earthquake and structural engineering. This book provides the state-of-the-art on recent progress in the field of seimology, earthquake engineering and structural engineering. The book should be useful to graduate students, researchers and practicing structural engineers. It deals with seismicity, seismic hazard assessment and system oriented emergency response for abrupt earthquake disaster, the nature and the components of strong ground motions and several other interesting topics, such as dam-induced earthquakes, seismic stability of slopes and landslides. The book also tackles the dynamic response of underground pipes to blast loads, the optimal seismic design of RC multi-storey buildings, the finite-element analysis of cable-stayed bridges under strong ground motions and the acute psychiatric trauma intervention due to earthquakes

\u201cMASONRY ARCH BRIDGES IN VENICE: EXPERIMENTAL AND NUMERICAL PROCEDURES FOR STRUCTURAL IDENTIFICATION\u201d

Masonry arch bridges are an important part of architectural historical heritage. Their presence is a characteristic feature of the Italian and European landscape. A large number of research and studies about. This theme have been produced in literature during time. Regarding Venetian bridges, except for the most famous architectures. Data are lacking given by research results are lacking. A procedure for structural identification and for the evaluation of the material mechanical characteristics for historical masonry bridges is here presented with the aim of their conservation and restoration. The procedure, based on experimental measurements and numerical analyses, requires, at first, the measurements of the bridge\u2019s fundamental frequencies, then, through the calibration of bridge FE Model, allows the estimation of the average materials characteristics. In particular, for the frequency acquisition data, the procedure proposes the use of a compact digital tromograph, a highly sophisticated measuring device, equipped with accelerometric and velocimetric transducers, that allows fast and low cost vibration measurements. Successive analyses, by means of fast Fourier transform, permit to estimate the fundamental frequency of the structure. For one study case the validity of the results obtained is confirmed by making a comparison with a measurement campaign performed using accelerometers as instruments