Masonry Italian Code-Conforming Buildings. Part 2: Nonlinear Modelling and Time-History Analysis

ABSTRACT

The unreinforced masonry (URM) buildings designed to be conforming with the Italian building code, as illustrated in the companion paper, were analyzed by performing time-history analyses on models realized using an equivalent frame approach and by adopting two different constitutive laws. Both the effect of record-to-record variability and of epistemic and aleatory uncertainties in modelling were explored. The achieved results constitute the basis for the evaluation of the risk level implicit in Italian code-conforming buildings. Two main performance conditions are considered, namely usability-preventing damage and global collapse limit states.     

从东西方历史建筑的差异看东西方文明

东西方历史建筑在建筑材料、建筑类型、空间布局、发展演变和留存时间等诸多方面存在差异。究其原因,二者在自然环境、经济模式、宗教思想、社会意识和自然观方面的不同特点是造成这些差异产生的主要原因,而这些差异也体现了东西方文明的不同风格。     

SIGNIFICANT GROUND MOTION PARAMETERS FOR EVALUATION OF THE SEISMIC PERFORMANCE OF SLENDER MASONRY TOWERS

The evaluation of seismic risk of masonry monuments requires to study the combination of vulnerability and hazard. In the present work, the global seismic response of slender masonry towers has been studied by means of a specific 3-D fibre model. Accounting for the particular behaviour of such structures, the hazard should also be described by a suitable measure of intensity of the seismic action. A variety of different parameters relating with the ground acceleration recordings have been investigated for what regards their correlation with the damage indicators of the model. The combination of the peak ground velocity of the horizontal component and of the significant duration is an effective measure of intensity. This measure can be improved by considering the accord of the frequency content of the ground motion with the dynamical characteristics of the tower. Since in some cases the effect of the vertical component proved to be important, a further improvement can be obtained by taking into account also the vertical ground motion intensity.     

TORSIONAL EFFECTS IN THE PUSHOVER-BASED SEISMIC ANALYSIS OF BUILDINGS

The general trends of the inelastic behaviour of plan-asymmetric structures have been studied. Systems with structural elements in both orthogonal directions and bi-axial eccentricity were subjected to bi-directional excitation. Test examples include idealised single-storey and multi-storey models, and a three-storey building, for which test results are available. The response in terms of displacements was determined by nonlinear dynamic analyses. The main findings, limited to fairly regular and simple investigated buildings, are: (a) The amplification of displacements determined by elastic dynamic analysis can be used as a rough, and in the majority of cases conservative estimate in the inelastic range, (b) Any favourable torsional effect on the stiff side, which may arise from elastic analysis, may disappear in the inelastic range. These findings can be utilised in the approximate pushover-based seismic analysis of asymmetric buildings, e.g. in the N2 method. It is proposed that the results obtained by pushover analysis of a 3D structural model be combined with the results of a linear dynamic (spectral) analysis. The former results control the target displacements and the distribution of deformations along the height of the building, whereas the latter results define the torsional amplifications. The proposed approach is partly illustrated and evaluated by test examples.     

汉口徽商与社会风尚--以《汉口丛谈》为例

从<汉口丛谈>的记载可以看出,汉口徽商与扬州徽商的基本特征还是相同的,由于地理位置的不同,也由于作者关注事物眼光的不同,我们看到的汉口徽商有着一些与扬州徽商稍微不同的生活方式和精神风貌,地域的烙印比较明显.     

屯堡民居石木结构建筑的艺术象征

屯堡民居建筑秉承中原江淮建筑的文化内涵,具有军事上和江淮母源地文化的特征,又具有黔中山地特点的表征,创造出木石主体结构的黔中防御性建筑,成为安顺屯堡文化的重要组成内容,形成了独特的建筑文化景现。本文从历史学、文化地理学的角度对屯堡建筑景观的构成、流变进行探析。     

试论隋唐东西两京布局差异的成因

隋唐长安城和洛阳城因在政治、经济、文化等方面有诸多的相似性,在当时就被称为东西两京。但二者的布局差异之大,令人费解。许多学者对此提出了不同的看法,但仍没有一个合理的解释。本文拟在前人研究基础上,对流行的几种观点予以评述,提出自己的观点,并求教于方家。     

Nonlinear Structural Performance of a Historical Brick Masonry Inverted Dome

ABSTRACT

Traditional domes are obtained by double curvature shells, which can be rotationally formed by any curved geometrical plane figure rotating about a central vertical axis. They are self-supported and stabilized by the force of gravity acting on their weight to hold them in compression. However, the behavior of inverted domes is different since the dome is downward and masonry inverted domes and their structural behaviors in the literature received limited attention. This article presents a nonlinear finite element analysis of historical brick masonry inverted domes under static and seismic loads. The brick masonry inverted dome in the tomb of scholar Ahmed-El Cezeri, town of Cizre, Turkey, constructed in 1508 is selected as an application. First, a detailed literature review on the masonry domes is given and the selected inverted dome is described briefly. 3D solid and continuum finite element models of the inverted masonry dome are obtained from the surveys. An isotropic Concrete Damage Plasticity (CDP) material model adjusted to masonry structures with the same tensile strength assumed along the parallel and meridian directions of the inverted dome is considered. The nonlinear static analyses and a parametric study by changing the mechanical properties of the brick unit of the inverted masonry dome are performed under gravity loads. The acceleration records of vertical and horizontal components of May 1, 2003 Bingöl earthquake (Mw = 6.4), Turkey, occurred near the region, are chosen for the nonlinear seismic analyses. Nonlinear step by step seismic analyses of the inverted dome are implemented under the vertical and horizontal components of the earthquake, separately. Static modal and seismic responses of the inverted masonry dome are evaluated using mode shapes, minimum and maximum principal strains and stresses, and damage propagations.     

推拉动机对存在原真性和忠诚度的影响实证研究——以福建土楼为例

本研究结合存在原真性理论,以福建永定土楼为案例地,搭建推拉动机-存在原真性-游客忠诚度的概念模型,其中还考虑存在原真性分为人内原真性和人际原真性的情况。研究结果显示：在总模型中,拉动机、推动机相关;拉动机、推动机正向影响存在原真性,拉动机正向影响忠诚度,推动机对忠诚度影响微弱、不显著;存在原真性正向影响忠诚度;在分模型中,拉动机、推动机相关;拉动机正向影响人内原真性和人际原真性;推动机正向影响人内原真性,但对人际原真性的影响微弱且不显著;拉动机正向影响忠诚度,推动机对忠诚度影响微弱、不显著;人内原真性对人际原真性具有正向的影响作用。本研究为文化遗产地景区的开发、经营及活动设计等方面提供相关建议。