Earthquake engineering

Abstract

In 2012 an earthquake measuring 3.6 on the scale of Richter struck the village of Huizinge; this quake was the heaviest so far recorded in the region. This shocked the community: earthquakes, a serious threat in the Netherlands? The earthquakes are acknowledged to be caused by the production of natural gas of the Groningen gas field. A predominant part of the building stock is built with unreinforced masonry, which performs poorly during earthquakes due to its brittle behavior and lack of ductility. Besides the large scale upgrading task which lays ahead, the building community is challenged to develop a shock-proof approach for new buildings. Earthquake engineering might seem to be a very technical subject, concerning mainly structural aspects. However, seismic principles and techniques have a large impact and pose serious limitations on the design. How to develop an optimal design strategy dealing with the constraints posed by seismic principles on aspects such as architectural and functional quality? First, the performance of existing buildings was researched. What are their weaknesses? What are their strengths? Then the main strategies and principles were researched to combat earthquake loads. I made an overview of objectives for the building: what is it supposed to do, in what sort of environment does it stand, what are the architectural ambitions and so on. Then I constructed a matrix, matching these building objectives and criteria on the one hand with different reinforcement techniques and strategies on the other hand. By learning from the weaknesses of the existing building stock, the research provided guidelines and inspiration for the design of a new building in Loppersum: the public interface for the Governmental Department for earthquakes (Rijksdienst voor Aardbevingen) towards the public. This building will be a representative information point in the region, housing office spaces for consults and the handling of damage claims. An integral performance objective was set up for the building. Besides a showcase for earthquake proof building, is should be inviting, architecturally pleasing and sustainable. Its design will be showcase of how one can build for earthquakes in an innovative way, moving from heavy and stiff structures towards light and flexible methods. The building is designed to have an inviting entrance, followed up by communal entrance platforms for information services and presentation spaces. It also houses a pleasant office area and a generous public space covered by a spectacular angled roof, with translucent panels flooding the building with natural light. A structural technique was applied (pre-stressed laminated timber technology), in conformity with all the earthquake principles stated in the research: placing resisting elements at the perimeter of the building, using light and ductile materials, providing adequate connections, stiff floors, regular plans and making use of energy dissipation. The structure exists of timber elements, with tensioned cables running through which are clamped in the foundation. This approach allows the building to rock back and forth on its foundation. The tensioned cables will pull the building back upright (self-centering). The connections are designed to allow for this movement. The rest of the building is made with light and flexible alternatives for conventional building solutions, such as plastic cushion windows and timber composite concrete floors. The design has resulted in an exciting building, made shockproof by all kinds of innovative earthquake principles.