Luís Guerreiro

Recent earthquakes have shown that earthquake-induced landslides and liquefaction can severely disrupt transportation systems and generate significant direct and indirect losses. Still, these secondary hazards are rarely incorporated into regional road-network disruption assessments. This paper presents a scenario-based multi-hazard methodology, implemented in the OpenQuake-engine, for integrating ground shaking, earthquake-induced landslides, and liquefaction into transportation-network analysis. The workflow combines hazard modelling, component-level damage and operability assessment, and network-based performance metrics. The methodology is demonstrated for the major road network of Southern Portugal using three representative earthquake scenarios. The results show that ground shaking is the dominant driver of regional disruption, but liquefaction and landslides can contribute locally to asset non-operationality and connectivity loss, particularly where susceptible ground conditions coincide with critical network links. The results also show that multi-hazard impacts are not simply additive, because network disruption depends on the spatial configuration and overlap of affected components. Compared with ground-shaking-only analyses, the proposed approach provides a more complete representation of road-network disruption and helps identify locations where secondary hazards may compromise network redundancy and emergency accessibility.

The seismic performance of a prefabricated ultra‐thin triangular shell dome structure developed in the scope of the Prefabricated Ultra‐Thin Concrete Shells project was investigated through shake table tests. Shell dome structures are usually designed to withstand vertical loads, but in seismic‐prone regions, they also must sustain horizontal seismic forces. Following the architectural and engineering design presented in the companion papers, a set of experimental tests were carried out on the LNEC 3D seismic table with a 1:3 reduced‐scale model of the developed prototype produced by the prefabrication company SPRAL. An extensive testing protocol was carried out during which horizontal seismic actions were imposed in two orthogonal directions. The reference seismic action, generated from the regulatory spectra in NP EN 1998‐1:2010, was scaled by several multiplicative factors from 25% to 400% and applied sequentially. The specimen was instrumented with accelerometers at various points to estimate the inertia forces generated and displacement transducers at the joints between prefabricated elements to record any relative movements. Dynamic properties (frequencies, mode shapes, and damping coefficients) were tracked during the testing sequence to detect eventual degradation due to the seismic tests. The combination of the various results with the observations made during the tests made it possible to evaluate the seismic performance of the specimen. The seismic tests demonstrated that the thin shell dome structure was able to sustain horizontal seismic loads above the seismic design level.

Project SHELTER, Structural Hyper-resisting Element for Life-Threatening Earthquake Risk, aims at developing a strong and stiff functional unit to protect its occupants in case of severe earthquakes that lead to structural collapse. In case of collapse, these units will suffer impacts, particularly if they are installed in upper floors. To avoid severe injuries or death of occupants caused by collapse, safety chairs were designed, provided with shock-absorber systems and auxiliary retaining devices, to keep the occupants properly seated and safe. Three downfall scenarios were evaluated, consisting of vertical and tilted positions. A comprehensive numerical model to represent the human body was developed, mainly focused on chest behaviour and considering the anatomic limits of the vertebral spine. The mechanical ability of the safety chair to ensure the occupants’ safety was evaluated under these harsh conditions. Experimental downfall-and-impact tests will later be performed on shelter units, with crash-test dummies seated on the safety chairs for final validation.

The paper addresses the seismic vulnerability assessment of a multi-span footbridge, prone to span unseating due to shorter seat lengths. The structure is representative of a series of pedestrian crossings located in the Southern part of Portugal, a region with a relevant seismicity. A probabilistic approach allows considering the variability of the seismic action and uncertainties in the definition of the material properties and/or structural behavior. Based on incremental dynamic analyses and corresponding fragility curves, it is shown that, for code compliance design acceleration, there is a significant probability that the structure will only suffer minor damage.

Timber-framed wall buildings are seen all over Europe, especially in seismic regions, given its adequacy to resist earthquakes. The “Pombalino” buildings, developed after the great 1755 earthquake that destroyed Lisbon, constitute one of the best examples of historic seismic-resistant structures based on timber-framed masonry walls. The research presented in this article aimed at experimentally evaluating the seismic behavior of the “Pombalino” buildings. The experimental program was based on extensive dynamic testing on sub-structures of typical “Frontal” walls (the timber masonry walls), carried out at the LNEC (the Portuguese National Laboratory of Civil Engineering) shaking table. The tests comprised (a) seismic tests, in which the seismic action was applied with increasing amplitude in one direction; and (b) dynamic identification tests, aiming at evaluating the dynamic properties of the sub-structures and their evolution with damage accumulation.