Abstract

Traditional constructions that combine wood with a filler material are widely used throughout the world.The geography and the context,in which they are built,have influenced their design[1].Several countries developed different techniques that evolved over the years.These structures have always been a topic of interest in engineering for the interaction between the timber and the masonry.The understanding of these buildings is essential to figure out the solutions to preserve historic values.Modern societies must find the right strategies to conserve these timeless heritages[2].

The purpose of this study is to compare different construction techniques used in China and Europe,and try to find the optimal solution among the timberedframe structures.The comparison of samples under cyclic static loading tests is performed.Five specimens are investigated:bare timber frame without infill(F1,Chuan-dou main frame)then retrofitted with masonry infill(F1R,retrofitted Chuan-dou main frame);timber frame with masonry infill(F2,Chuan-dou main frame with masonry infill);timber frame with masonry infill and the single timber cross-bracing(F3,Italian Baraccato system);timber frame with masonry infill and the zigzag timber bracings(F4,Italian Maso system);timber frame with masonry infill and the double timber cross-bracing(F5,Portuguese Pombalino system),as shown in Figure 1.

Figure 1　Prospective view of the specimens

For each specimen,the main frame is assembled with the mortise and tenon joints without the application of metal fasteners.Moreover,the wooden diagonals elements follow the traditional European construction techniques with the use of half-lapping joints and screws.The specimens were made in the State Key Laboratory of Disaster Reduction in Civil Engineering at Tongji University,Shanghai.The main forces applied during the experiments were:one horizontal load by a hydraulic actuator and concentrated vertical loads by two hydraulic jacks.The CUREE loading protocol was used,as shown in Figure 2.

Figure 2　Wooden members of each bare frame

The specimens show a nonlinear and inelastic behavior through the hysteresis curves(Figure 3).The mortise and tenon joints were subjected to slight rotation,which showed a semi-rigid behavior,without any structural damages.The results demonstrated that the combination of timber frame with masonry infill and diagonal bracings could enhance the Chinese traditional timber buildings.From these experiments,the resistance of traditional constructions to historical seismic activity could be understood,compared to newly reinforced concrete structures.These traditional technologies could be an eco-friendly alternative in the construction industry.Focusing on their mechanisms,weaknesses and strengths,it is possible to keep using this traditional construction to improve their structural behavior for the future generations.

Figure 3　Hysteresis curves of various frame specimens