Purpose -The purpose of this paper is to establish the damage alarming indexes for ancient wood structures and study the damage sensitivity and noise robustness of these indexes under random excitation. Design/methodology/approach -Xi'an Bell Tower is taken as a case in this paper to simulate the damage of ancient wood structures through finite element (FE) simulation and determine the satisfactory damage alarming indexes with wavelet packet energy spectrum. Findings -The results of this paper show that: 1) the damage alarming indexes can effectively identify the damage of ancient wood structures, each index with a different damage sensitivity; 2) the energy ratio deviation is greater than the energy ratio variance and is close to the maximum variation of energy ratio; 3) the energy ratio deviation has a better alarming effect than the energy ratio variance during the initial period of the damage. With the accumulation of the damage, the energy ratio variance outperforms the energy ratio deviation; 4) the sensitivity of the energy ratio deviation and variance varies from positions, changing from the highest to lowest at the mortise-and-tenon joints, the beam mid-span and the plinth; 5) if signal to noise ratio (SNR) is 40db or larger, the indexes can accurately identify the damage of ancient wood structures. As SNR increases, the indexes will have an increasingly higher sensitivity and certain ability to resist noise. Research limitations/implications -The FE model is simpiy, it does not completely reflect Xi'an Bell Tower. Practical implications -It will provide a theoretical basis for the damage alarming of Xi'an Bell Tower. Social implications -It makes structural health monitoring through structural vibration response under ambient excitation a new research field in damage detection as well as a positive way of ancient architecture protection. Originality/value -This paper studies the damage alarming effect on ancient wood structures from different wavelet functions and wavelet packet decomposition levels. To study the effect under white noise environment, this paper adds Gaussian white noise with a SNR of 10, 20, 30, 40 and 50 db to the acceleration response signal of intact structure and damaged structure.

Assembled precast concrete structure is composed of precast element, which needs to be assembled and connected as the main force component. It is propitious to the development of building industrialization, enhancing production efficiency and promoting green building. Seismic response of a 6 storey assembled precast concrete residence was analyzed based on finite element software ANSYS. The results show that stiffness of assembled precast concrete residence is larger, and all of interbedded drift angles comply with stipulations of the standard.

Taking Xian Bell Tower and metro line 6 as research background, at first, according to the theory of Euler-Bernoulli beam in Winkler foundation, the analysis model of train-track-foundation system was established, and then, time-history curve of metro-induced loading acts on tunnel structure is obtained by using Matlab software. Two-dimensional finite element model of the structure-soil-tunnel interaction model was established using software Ansys,. Taken loading time delay into consideration for the first time, dynamic response law of the bell tower under the metro-vibration loading is obtained. Finally, the impact of metro line 6 on Xian Bell Tower was evaluated according to the Technical specification for protection of historic buildings against man-made vibration. Xi'an Bell Tower timber structure is safe when two trains running of the line 6.

The "box structure" is a building system which was highly prefabricated and assembled. Taking the "box structure" residence as an example, the static and dynamic performance is discussed and finite element analysis software ANSYS is applied to verify "box structure" design ideas.

Calcium silicate for filling material used in dissolved acetylene cylinders was prepared by adding alum as additive. Samples were characterized by X-ray powder diffraction (XRD) and scanning electron microscope (SEM). The effects of alum on the bleeding, shrinkage, strength, porosity, morphology and phase composition were studied. The experimental results show that the adding of alum can improve the comprehensive performance of samples. The mechanism was discussed in detail.