Frequencies Prediction of Laminated Timber Plates Using ANN Approach

Cross laminated timber(CLT)panels,which are used as load bearing plates and shear panels in timber structures,can serve as roofs,walls and floors.Since timber is construction material with relatively less stiffness,the design of such structures is often driven by serviceability criteria,such as deflection and vibration.Therefore,accurate vibration and elastic properties are vital for engineered CLT products.The objective of this research is to explore a method to determine the natural frequencies of orthotropic wood plates efficiently and fast.The method was developed based on vibration signal processing by wavelet to acquire the effective sample data,and a model developed by artificial neural network(ANN)to achieve the prediction of nature frequencies.First,experiments were performed to obtain vibration signals of single-layer plates.The vibration signals were then processed by wavelet packet transform to extract the eigenvectors,which served as the samples to train the ANN model.The trained model was employed to predict three nature frequencies of other test specimens.The results showed that the proposed method can produce predicted frequencies fast and efficiently within 10%of the measured values.

Numerical Investigation of Connection Performance of Timber-Concrete Composite Slabs with Inclined Self-Tapping Screws under High Temperature

The timber-concrete composite(TCC)slabs have become a preferred choice of floor systems in modern multi story timber buildings.This TCC slab consisted of timber and a concrete slab which were commonly connected together with inclined self-tapping screws(STSs).To more accurately predict the fire performance of TCC slabs,the mechanical behavior of TCC connections under high temperature was investigated by numerical simulation in this study.The interface slip of TCC connections was simulated by a proposed Finite Element(FE)model at room temperature,and different diameter and penetration length screws were considered.The effectiveness of this FE model was validated by comparing with the existing experimental results.Furthermore,the sequentially coupling thermal stress analyses of this model were conducted,and the relationship between the reduction coefficient of connection performance and the effective penetration length of screws was summarized.This study gave the fit-ting expressions for the reduction coefficient of slip modulus and joint strength.Finally,the numerical investiga-tions of the fire performance of TCC slabs considering the char fall-off of Cross Laminated Timber(CLT)were performed to verify the effectiveness of the proposed reduction law.Comparing the fire-resistance time with experimental results showed deviation of the proposed model was−14.02%.