Geotechnical Engineering Online Library

This paper examines and compares the minimum horizontal acceleration that is needed to initiate uplift of the single-nave barrel vault and of the rocking frame which are the two most common masonry structural systems used to bridge a span. The paper concludes that regardless of the direction of the rupture of the buttresses, the single-nave barrel vault uplifts with a seismic coefficient, ε, that is always smaller than the slenderness of the buttresses, s=b/h. In contrast, the rocking frame always uplifts with a seismic coefficient, ε=b/h, regardless of the mass of its prismatic epistyle; therefore, the rocking frame has a superior seismic performance than the single-nave barrel vault.

Contemporary seismic isolation systems for bridge applications provide a) horizontal isolation from earthquake shaking effects, and b) energy dissipation mechanisms to reduce displacements. Throughout the years, many kinds of seismic isolation mechanisms have been developed, with those incorporating negative stiffness elements being the most promising ones. The negative stiffness behaviour is achieved through special mechanical designs involving conventional positive stiffness pre-stressed elastic mechanical elements, arranged in appropriate geometrical configurations. In this context, a novel passive vibration isolation and damping concept is introduced, the KDamper, whose main advantage is that no reduction in the overall stiffness of the system is required. In this paper, the application of the KDamper concept on a typical concrete bridge with conventional bearings, to mitigate seismic effects, is considered. The system’s design is based on frequency domain analysis of both the initial and the isolated bridge structure. Comparative results between the two systems confirm that the proposed device can provide a promising alternative to conventional techniques, offering numerous advantages, such as increased damping and simple technological implementations.

The Canterbury Earthquake Sequence (2010 – 2011) caused significant damage and loss of life in Christchurch, New Zealand. The Earthquake Commission (EQC) is New Zealand’s public insurer for natural disaster damage. EQC determined that a new, claimable form of land damage had resulted due to the Increased Flooding Vulnerability (IFV) caused by the subsidence of the land changing the flood risk to residential properties. Tonkin & Taylor Ltd (T+T) on behalf of EQC had by early 2016 completed engineering assessments of over 11,000 residential properties in Canterbury. The purpose of the assessments was to understand and quantify the effects on residential properties of IFV caused by the Canterbury Earthquake Sequence. The completion of these assessments has involved over 75,000 man-hours and is the culmination of 5 years of data collection, policy and methodology development, legal and peer review. This paper examines some of the engineering challenges and how they were dealt with. It also considers what lessons could be learned if the process was to be repeated.

Safety of motorway users in case of a strong seismic event is directly related to the performance of infrastructure elements, especially motorway bridges. Preventive closure until post–seismic inspection may seem as the safest option, but will unavoidably lead to severe deterioration of serviceability, and will also obstruct the operations of rescue teams. On the other hand, allowing traffic on earthquake–damaged bridges without inspection may jeopardize the safety of users and rescue teams. Seismic retrofit is the obvious solution, but the associated costs can be quite substantial. An alternative strategy is to mitigate the indirect consequences of an earthquake, through timely development and implementation of a RApid REsponse (RARE) system. The scope of such a RARE system is to ensure the safety of motorway users, minimizing motorway network closure, and optimizing post-seismic recovery at the same time. The development of such a RARE system requires an effective means to estimate seismic damage in real time. This paper presents an overview of the RARE system and some first steps that were made regarding its pilot application in the Attiki Odos Motorway in Athens, Greece.

On the 16th of April 2016, the Kumamoto earthquake (Mw 7.0) hit the Central Kyushu Region, Japan, following a Mw 6.2 shock on the 14th of April. The earthquake sequences caused severe damage in Kumamoto Prefecture. This paper presents quick reconnaissance results focusing on geotechnical damage features, which were observed during field investigations immediately after, one, and two weeks after the main shock. The damage surveys were carried out in southern Kumamoto City, Mashiki Town, Aso Caldera area and their suburbs. In southern Kumamoto City, evidence of liquefaction was found at many locations, and some buildings and river levees suffered from significant settlement and deformation; damage to an embankment of Kyushu Highway also seemed to be the result of liquefaction. The majority of the damaged residential houses were found in Mashiki Town and its suburbs, which may be linked to intense earthquake motions associated with the seismic fault location. In Aso Caldera area, a number of moderate to large scale landslides and their significant impact to structures were observed. The greater part of landslide masses in Aso Caldera area was a mixture of volcanic ash, andsol, a highly porous dark-colored material comprising of volcanic ash mixed with organic matter, and pumice. These porous materials might have experienced significant strength reduction during the earthquake.