Carmen Sandhaas

A Proposal for a Procedure to Evaluate the Seismic Vulnerability of Historic Timber Frame Buildings

The seismic vulnerability of historic timber frame building heritage is difficult to quantify in retrospect. However, in order to maintain, restore or even retrofit these buildings, it is indispensable not only to understand their performance under an earthquake loading, but also to gain quantitative information on stiffness, load bearing capacities and failure modes of the used timber frame technique. A possibility to assess earthquake behaviour is full-scale testing, but this is very expensive and it is nearly impossible to cover all the different timber frame systems, the variations between the different systems and different earthquake loadings. Therefore, small-scale tests on components or substructures are more suitable whose outcomes can be used for nonlinear dynamic modelling of buildings. This contribution proposes a simple testing-modelling approach to quantify the seismic vulnerability of timber frame buildings. The testing includes monotonic and quasi-static reversed cyclic tests on shear walls which are re-built specimens mirroring as exactly as possible the historic archetypes for both wall dimensions and used materials. The test results are then used to develop nonlinear dynamic lumped mass models which are subjected to various earthquake accelerograms. By increasing the single earthquake’s peak ground acceleration (PGA) values, the seismic performance of the investigated historic structure can be evaluated and suggestions can be given with respect to restoring or retrofitting measures. On the basis of a valid and reliable mathematical model, also parameter studies varying, for instance, the number of fasteners in joints are more readily carried out than with experimental methods.

Timber Engineering - Principles for Design

This comprehensive book provides in-depth knowledge and understanding of design rules according to Eurocode 5. It is based on the first edition of the STEP (Structural Timber Education Programme) series, which was prepared in 1995 by about 50 authors from 14 European countries. The present work updates and extends the STEP compilation and is aimed at students, structural engineers and other timber structure professionals.

Seismic Vulnerability of Borbone Masonry Reinforced with Timber Frames

After the 1783 earthquake, under the Borbone kingdom, new building regulations were introduced in the Calabria region (Italy) with the main scope of reducing the seismic vulnerability of the building asset in these highly seismic areas. The Borbone system consisted of masonry walls reinforced with timber frames and prescribed a symmetrical development in plan and elevation as well as height limitations. These measures aimed at increasing the seismic resistance of buildings and hence, in general, at reducing the socio-economic impact of future seismic events. In order to maintain, repair or retrofit these buildings, it is indispensable not only to understand their qualitative performance under an earthquake loading, but also to gain quantitative information on stiffness, load bearing and energy dissipation capacity and failure modes. This paper presents first investigations on the seismic vulnerability of simple Borbone structures where modelling assumptions such regularity in plan and elevation hold and only one shear wall system was used. Re-built shear wall specimens mirroring as exactly as possible a wall of the Palazzo Vescovile in Mileto (Italy), built according to the Borbone Istruzioni after the 1783 earthquake, were tested under quasi-static cyclic in-plane loading. By means of these tests, lateral properties and damage patterns of Borbone shear walls under horizontal loading were assessed and, even if limited to a single panel, earthquake behaviour patterns were evaluated. The test results on the shear walls in terms of hysteretic loops were used to develop a non-linear dynamic lumped mass model of a case study Borbone building which was subjected to various earthquake accelerograms. The single earthquake’s peak ground acceleration (PGA) values were increased until a previously defined near-collapse state in terms of maximum interstorey drift of the modelled building was reached. The thus obtained ultimate values for the PGA represent the sustainable level of seismic action of the investigated Borbone structure and ranged from 0.25g (North American earthquake) up to 1.52g. The effectivity of Borbone building regulations could be shown.

Innovative timber building systems: comparative testing and modelling of earthquake behaviour

Several innovative timber building systems were developed in the past few years, among which dowel-laminated timber, CLT with interspaces and prefabricated timber wall elements, whose design requires also verification of the lateral load-carrying system. Therefore, shear wall tests on these three building systems were carried out. Timber frame shear walls were also tested to compare load–displacement behaviour, failure modes and energy dissipation capacity. The four investigated systems exhibit similar shapes for load–displacement curves albeit reaching different stiffness and capacity values. Based on the test results, 2D models of shear walls and a case study building were developed in order to investigate the seismic behaviour of the discussed timber building systems. The hysteretic behaviour of the shear walls and of the case study building was assigned to non-linear hysteretic springs. The building models were then subject to accelerograms whose intensities were increased until the near-collapse state was reached. Via these nonlinear dynamic simulations in the time domain, design behaviour factors valid for force-based seismic design were established. Based only on a few common tests on shear walls, a general statement regarding the seismic behaviour of novel systems can be given using this procedure. The three investigated innovative timber building systems proved to be suitable for the use in seismic active areas and can cover the same application range as conventional timber frame buildings.

Statisches und dynamisches Verhalten von aussteifenden Wandscheiben in Brettstapelbauweise

Verbindungen und aussteifende Wandscheiben in Brettstapelbauweise wurden experimentell untersucht und abschliesend beurteilt. Anhand eines nichtlinearen dynamischen Gebaudemodells, dessen Eingabeparameter auf Ergebnissen von zyklischen Wandscheibenversuchen beruhen, wurde das allgemeine Erdbebenverhalten untersucht und erste Aussagen zum Verhaltensbeiwert q getroffen.

Ingenieurholzbau - Grundlagen der Bemessung

Dieses Werk ist ein umfassendes Lehrbuch fur den Ingenieurholzbau und vertieft das Verstandnis der Grundlagen der Bemessungsregeln des Eurocode 5. Es baut auf der ersten Ausgabe der STEP-Reihe, den Buchern des Structural Timber Education Programme, auf, die 1995 von etwa 50 Autoren aus 14 europaischen Landern erarbeitet wurden. Das vorliegende Buch ist eine aktualisierte und erweiterte Ausgabe und richtet sich an Studierende, Tragwerksplaner und weitere Praktiker des Holzbaus.