Vertical ground motion influence on seismically isolated & unisolated bridges

Rehanoğulları, Naim Eser
In this study influences of vertical ground motion on seismically isolated bridges were investigated for seven different earthquake data. One assessment of bearing effect involves the calculation of vertical earthquake load on the seismically isolated bridges. This paper investigates the influence of vertical earthquake excitation on the response of briefly steel girder composite bridges (SCB) with and without seismic isolation through specifically selected earthquakes. In detail, the bridge is composed of 30m long three spans, concrete double piers at each axis supported by mat foundations with pile systems. At both end of the spans there exists concrete abutments to support superstructure of the bridge. SCBs which were seismically isolated with nine commonly preferred different lead‐rubber bearings (LRB) under each steel girder were analyzed. Then, the comparisons were made with a SCB without seismic isolation. Initially, a preliminary design was made and reasonable sections for the bridge have been obtained. As a result of this, the steel girder bridge sections were checked with AASHTO provisions and analytical model was updated accordingly. Earthquake records were thought as the main loading sources. Hence both cases were exposed to tri‐axial earthquake loads in order to understand the effects under such circumstances. Seven near fault earthquake data were selected by considering possession of directivity. Several runs using the chosen earthquakes were performed in order to be able to derive satisfactory comparisons between different types of isolators. Analytical calculations were conducted using well known structural analysis software (SAS) SAP2000. Nonlinear time history analysis was performed using the analytical model of the bridge with and without seismic isolation. Response data collected from SAS was used to determine the vertical load on the piers and middle span midspan moment on the steel girders due to the vertical and horizontal component of excitation. Comparisons dealing with the effects of horizontal only and horizontal plus vertical earthquake loads were introduced.


Initiation of motion of coarse solitary particles on rough channel beds
Küçüktepe, Ömer İlker; Göğüş, Mustafa; Department of Civil Engineering (2009)
In this study the incipient motion of coarse solitary particles on channel beds having different roughness heights was experimentally investigated. The experiments were conducted in a tilting flume of a rectangular cross-section having a working length of 12 m and a rough bed composed of at least 2 layers of coarse gravel of almost constant size. The roughness material of the channel bed was changed three times. The slope of the channel bed and the discharge are two main parameters that determine the initia...
Energy based seismic performance assessment of reinforced concrete columns
Acun, Bora; Sucuoğlu, Haluk; Department of Civil Engineering (2010)
Severe seismic events in urban regions during the last two decades revealed that the structures constructed before the development of modern seismic codes are the most vulnerable to earthquakes. Sub-standard reinforced concrete buildings constitute an important part of this highly vulnerable urban building stock. There is urgent need for the development and improvement of methods for seismic performance assessment of existing reinforced concrete structures. As an alternative to current conventional force-ba...
Seismic response of multi-span highway bridges with two-column reinforced concrete bents including foundation and column flexibility
Yılmaz, Taner; Caner, Alp; Department of Civil Engineering (2008)
Seismic design of highway bridges has improved as a result of the experience gained from large earthquakes of the last thirty years. Ductility demand and reserved capacity are extremely important response measures used in new bridge designs to assess target damage levels. However, the application of practical design approaches specified in bridge design codes is not well-defined for bridges over flexible foundations. Within the scope of this research, thirty two bridge models having varying column aspect ra...
Investigation of strenghthening techniques using pseudo-dynamic testing
Kurt, Efe Gökçe; Özcebe, Güney; Department of Civil Engineering (2010)
Pseudo-dynamic testing was employed to observe the seismic performance of three different retrofit methods on two story three bay reinforced concrete frame structures. The three test frames have hollow clay tile (HCT) infills in the central bay. All of the test frames represent the seismic deficiencies of the Turkish construction practice such as use of plain reinforcing bars, low strength concrete and insufficient confining steel. Two non-invasive and occupant friendly retrofit schemes suggested in the Tur...
Incipient motion of coarse solitary particles
Gülcü, Besim; Göğüş, Mustafa; Department of Civil Engineering (2009)
In this study the incipient motion of coarse solitary particles having different specific weights and shapes was investigated. A tilting flume of rectangular cross-section having a net working length of 12 m was used through the experiments. The slope of the channel and the discharge in the channel are the two basic variable parameters that determine the initiation of motion. Particles made of cement and mixture of cement and iron dust in certain ratios were used in the experiments with an obstructing eleme...
Citation Formats
N. E. Rehanoğulları, “Vertical ground motion influence on seismically isolated & unisolated bridges,” M.S. - Master of Science, Middle East Technical University, 2010.