This paper deals with the seismic behaviour of timber-glass systems. A series of experiments was performed on the shaking table of the IZIIS institute in Skopje, Macedonia. One and two story full scale structures were subjected to a series of ground motions. All together 8 different setups were tested. The chosen combination of glass-timber walls exhibited a rocking type of behaviour, resulting in a desirable ductile failure of steel hold-downs and not brittle failure of the glazing or the timber frame.
The study presented herein proposes a retrofit method aimed at reducing the seismic vulnerability of reinforced concrete (RC) frame structures. The method consists in the replacement of the existing masonry infills with timber structural panels made of Cross Laminated Timber (CLT) fixed to the concrete frame by using a timber subframe and dissipative metal dowel-type fasteners. The first part of the research was carried out by performing nonlinear static analyses of finiteelement (FE) models of bare, masonry infilled and retrofitted single-storey single-bay frames. A large number of configurations was analysed considering different original conditions (e.g. in terms of geometrical characteristics, mechanical properties and loading) and several retrofit implementation approaches. Special attention was paid to the improvement of the seismic response of the beam-column joints, that represent a well-known structural vulnerability of existing concrete frame-buildings. The analysis results permitted to define a set of “general rules” to guide the implementation of the retrofit method depending on the characteristics of the original structure. Using these design rules, the proposed solution was then applied to the FE models of three case-study buildings, located in Italy and built in the period from 1950 to 1990. By comparing the seismic response of the pre- and post-intervention structures, it was observed that the proposed system could significantly improve the structural behaviour of the buildings, favouring the development of ductile mechanisms and reducing the vulnerability of the beam-column joints.
New Zealand Society for Earthquake Engineering Conference
March 21-23, 2014, Auckland, New Zealand
This paper describes results of shaking table testing of a post-tensioned timber frame building in the structural laboratory of the University of Basilicata in Potenza, Italy. This experimental campaign is part of a series of experimental tests in collaboration with the University of Canterbury in Christchurch, New Zealand. The specimen was 3-dimensional, 3-storey, 2/3rd scale and constructed using post-tensioned timber frames in both directions. The structure was tested with and without dissipative steel angle reinforcing which was designed to yield at a certain level of drift. These steel angles release energy through hysteresis during seismic loading, thus increasing damping. Testing was performed up to a maximum PGA of 0.77g with and 0.58g without the dissipative reinforcing. At comparable levels of PGA the addition of the reinforcing reduced drifts by 32% without increases in peak floor accelerations. Test results were also compared favourable against numerical blind predictions using the RUAUMOKO 2D and SAP2000 structural analysis programs.
New Zealand Society for Earthquake Engineering Conference
April 26-28, 2013, Wellington, New Zealand
Post-tensioned timber (PRES LAM) is a new form of seismic resistant construction which already has real building applications throughout New Zealand. The innovative high seismic performance system combines the use of precast concrete PRESSS technology and engineered wood products combining post-tensioning elements (providing recentring) with large timber members. Additional steel dissipation devices are often also placed in order to provide additional strength and dissipative capacity.
The following paper describes the design, fabrication and set-up of a dynamic testing campaign to be performed in the structural laboratory of the University of Basilicata (UNIBAS) in Potenza, Italy. The test specimen is a 2/3rd scale, 3-storey post-tensioned timber frame and wall are to be studied both with and without the addition of dissipative steel angles which are designed to yield at a certain level of drift in order to provide the desirable ‘flag shaped’ hysteretic response. These steel angles release energy through hysteresis during movement thus increasing damping as well as providing additional strength. The ratio between post-tensioning and energy dissipation provided will be altered between tests in order to investigate their contribution to dynamic frame performance. The specimen will be subjected to an increasing level of seismic loading using a set of 7 natural earthquakes selected from the European Strong Motion database.
This paper first describes the testing set-up, the fabrication of the test specimen and testing apparatus and the selection of cases which will be tested.
This thesis discusses the development of a new innovative reinforced concrete hybrid structure. The hybrid structure consists of reinforced concrete frame incorporated with Cross Laminated Timber (CLT) and metallic damper connections. The seismic design of this proposed system was carried out with the displacement-based design framework and the design was successfully verified. First, this study focused to numerically model the conventional metallic (steel slit) damper and validated with the experimental result using the Abaqus finite element program. Then, to minimize the drawbacks of the conventional damper specimen, a parametric study has been carried out by changing the shape parameters of the damper using the factorial design of experiments. The purpose of conducting a parametric study is to find the appropriate configuration of the damper which can perform well with the proposed hybrid system. Further, the importance of the shape parameter and their interactions in the final response was studied using the response surface method. Secondly, the proposed hybrid system with the metallic damper connection was modeled in Extended Three Dimensional Analysis of Building Systems (ETABS) and then the overall behavior of the system was investigated. In addition, a direct displacement-based design framework was developed for the seismic design of this proposed system. To verify the proposed framework, a 2D six storey hybrid structure was modeled using ETABS. Then, a nonlinear time history analysis was conducted for the modeled structure using 50 set of ground motions to evaluate its performance. The results indicate that the proposed design framework is effective in controlling the displacement of the hybrid system under seismic excitation.
IOP Conference Series: Materials Science and Engineering
In recent years, development of wood engineering is gradually increasing. Instead of using many wood columns, cross laminated timber is expected for constructing spacious open space building. Since cross-laminated timber has high rigidity and strength, cross-laminated timber is expected to be used as earthquake resistant wall or floor diaphragm that makes the span of building can be increased and the position of the wall can be adjusted openly. In order to optimize the performance of cross-laminated timber for open space building, original cross laminated timber core structure method was developed. In this paper, the development concept of original cross laminated timber core structure method will be explained. In this method, the joint connection for each element such as joint connection for wall-concrete foundation, wall-beam, and wall to hanging wall was also developed. The experiment to verify the strength and rigidity of each connection has been conducted and the result will be described. The shaking table experiment of 3-story open space building constructed by original cross laminated timber structure using varies earthquake waves was conducted. In this experiment natural period, shear force for each floor, story drift, and building response data is taken. The result shows the structure designed by original CLT core structure method is satisfy the requirement based on Japan cross-laminated panel structure regulation.
This thesis investigated light-frame wood/concrete hybrid construction as part of the NSERC Strategic Network on Innovative Wood products and Building Systems (NEWBuildS). A review of eight wood/concrete niche areas identified three with potential to be used in mid- to high-rise structures. Light-frame wood structures of seven or more storeys with wood/concrete hybrid flooring seem to have little feasibility unless a concrete lateral-load-resisting system is provided and material incompatibilities are solved. Non-load-bearing light-frame wood infill walls in reinforced concrete frame structures were recognized to have potential feasibility in mid- to high-rise structures. A full-scale, single frame test apparatus was successfully designed and constructed at the Insurance Research Lab for Better Homes. The frame is statically loaded to accurately replicates realistic horizontal sway and vertical racking deformations of a typical eight storey reinforced concrete frame structure at SLS and ULS. A linear-elastic analysis of the test apparatus was generally able to predict the results during testing. The 2.4m x 4.8m (8 ft. x 16 ft.) infill wall specimen did not satisfy serviceability deflection limitations of L/360 when subjected to representative out-of-plane wind pressures of +1.44/-0.9 kPa. The out-of-plane response was not significantly affected by horizontal sway deflections of +/-7.2mm or vertical racking deflections of +9.6mm. Although a nominal 20mm gap was provided to isolate the wall from the surrounding frame, insulation foam sprayed in the gap facilitated load transfer between them.
The material presented in this paper refers to a part of the investigation on cross-laminated (XLam) wall panel systems subjected to seismic excitation, carried out within the bilateral project realized by the Institute of Earthquake Engineering and Engineering Seismology (IZIIS) and the Faculty of Civil and Geodetic Engineering at the University of Ljubljana (UL FCGE). The full program of the research consista of basic tests of small XLam wooden blocks and quasi-static tests of anchors, then quasi-static tests of full-scale wall panels with given anchors, shaking-table tests of two types of XLam systems including ambient-vibration tests, and finally analytical research for the definition of the computational model for the analysis of these structural systems. In this paper, the full-scale shaking-table tests for one XLam system type (i.e. specimen 1 consisting of two single-unit massive wooden XLam panels) that have been performed in the IZIIS laboratory are discussed. The principal objectives of the shaking-table tests have been to get an insight into the behavior of the investigated XLam panel systems under seismic excitations, develop a physical and practical computational model for simutalion of the dynamic response based on the tests, and finally correlate the results with those from the previously performed quasi-static tests on the same wooden panel types. The obtained experimental results have been verified using a proposed computational model that included new contitutive relationships for anchors and contact zones between panels and foundations. Because a reasonable agreement between the numerical and experimental results has been achieved, the proposed computational model is expected to provide a solid basis for future research on the practical design of these relatively new materials and systems.