Mapping Mesolithic and Neolithic cultures behaviours and interactions with nature and properties of rocks in Western France

Multivariate statistical methods are used to study recent Prehistory lithics from the Armorican Massif, allowing us to classify them in more or less distinct groups according to the structural and mineralogical qualities of rock types involved. Analyses are carried out on metamorphic, sedimentary and magmatic rocks making up lithics collected from 31 localities. The petrographic properties are determined by polarizing microscope (POM), while the mechanical properties are obtained by Vickers's indentation method (VI), compression/traction (CT) and ultrasound echography (UE). The results provide us with important information about the management of lithic raw materials used by various human and cultural groups during the Mesolithic and Neolithic of the Armorican Massif. The more commonly used materials show a homogeneous and stable distribution of regional technology styles. The rock types exhibiting mature and homogeneous structures possess the better qualities for knapping (fracture energy G_Ic) and use (edge toughness M₁), and are more involved in exchange. The application of Upward Hierarchical Classification (UHC) and Principal Component Analysis (PCA) allows us to identify the classes of materials as well as the causes of variations of rock type abundance within the lithic assemblages of the Mesolithic and the Neolithic. In this way, we can then also predict the discovery of archaeological artefacts in areas lacking any known indications of the exploitation of outcropping materials.     

Flexural and Shear Damage Models for MRF Structures Excited by Far-Field Horizontal Strong Ground Motions

The unexpected damages in structures during severe earthquakes have been reported frequently so far. In this study, the damage-based inelastic behavior of special moment resisting frame (SMRF) structures designed according to the new versions of general earthquake loading codes (International building code [IBC] 2012 & American Society of Civil Engineers [ASCE] 7-2010) and seismic design references (National Earthquake Hazards Reduction Program [NEHRP] 2009 & Federal Emergency Management Agency [FEMA] P-750) has been investigated. The final results presented based on distinctive shear and flexural failure modes show that a non-uniform distribution of severe damage in structural height occurs during design level seismic excitations. Also it is observed that the shear and flexural damages are more critical in short and tall MRF structures, respectively.     

Development and Seismic Behavior of Precast Concrete Beam-to-Column Connections

A new precast concrete beam-to-column connection for moment-resisting frames was developed in this study. Both longitudinal bar anchoring and lap splicing were used to achieve beam reinforcement continuity. Three full-scale beam-to-column connections, including a reference monolithic specimen, were investigated under reversal cyclic loading. The difference between the two precast specimens was the consideration of additional lap-splicing bars in the calculation of moment-resisting strength. Seismic performance was evaluated based on hysteretic behavior, strength, ductility, stiffness, and energy dissipation. The plastic hinge length of the specimens is also discussed. The results show that the proposed precast system performs satisfactorily under reversal cyclic loading compared with the monolithic specimen, and the additional lap-splicing bars can be included in the strength calculation using the plane cross-section assumption. Furthermore, the plastic hinge length of the proposed precast beam-to-column connection can be estimated using the models for monolithic specimens.     

Earthquake-Induced Damage Detection in a Monumental Masonry Bell-Tower Using Long-Term Dynamic Monitoring Data

ABSTRACT

This work investigates the use of an advanced long-term vibration-based structural health monitoring tool to automatically detect earthquake-induced damages in heritage structures. Damage produced in a monumental bell-tower at increasing values of the Peak Ground Acceleration (PGA) of the seismic input is predicted by incremental nonlinear dynamic analysis, using a Finite Element model calibrated on the basis of experimentally identified natural modes. Then, predicted damage effects are artificially introduced in the monitoring data to check for their detectability. The results demonstrate that a very small damage, associated to a low intensity and low return period earthquake, is clearly detected by the monitoring system.     

Modeling and Seismic Response Analysis of Italian Code-Conforming Reinforced Concrete Buildings

ABSTRACT

This study investigates the seismic response of reinforced concrete buildings designed according to the current Italian building code. Number of stories, site hazard, presence and distribution of masonry infill panels, and type of lateral resisting system are the key investigated parameters. The main issues related to design and modeling are discussed. Two Limit States are considered, namely Global Collapse and Usability-Preventing Damage. The main aim of the study is a comparison between the seismic response of the buildings, investigated through nonlinear static and dynamic analyses. Irregularity in the distribution of infill panels and site hazard emerge as the most influential parameters.     

民国钢筋混凝土结构中的梁构件计算方法研究

为研究民国时期混凝土梁构件的设计计算方法,从材料层面到构件层面,对民国时期混凝土设计与结构计算的相关历史文献进行研究,总结出民国时期混凝土梁构件的设计与计算方法,并结合案例分析,与现代混凝土梁构件的设计计算方法进行比较研究,包括钢筋混凝土梁的受弯承载力计算方法及受剪承载力计算方法。通过对比计算分析,不考虑地震荷载作用时,在1.0%~2.0%纵筋配筋率的范围内,采用现行规范计算的受弯承载力是采用民国规范计算的受弯承载力的3.6~4.0倍;在配箍率0.1%~1.0%范围内,采用现行规范计算的受剪承载力是采用民国规范计算的受剪承载力的1.6~2.4倍;在弯起钢筋配筋率0.5%~1.5%范围内,采用现行规范计算的受剪承载力是采用民国规范计算的受剪承载力的2.0~2.4倍。研究结果可为民国钢筋混凝土梁的结构安全评估提供科学依据。     

Parameterized Seismic Fragility Curves for Curved Multi-frame Concrete Box-Girder Bridges Using Bayesian Parameter Estimation

This paper addresses the application of a Bayesian parameter estimation method to a regional seismic risk assessment of curved concrete bridges. For this purpose, numerical models of case-study bridges are simulated to generate multiparameter demand models of components, consisting of various uncertainty parameters and an intensity measure (IM). The demand models are constructed using a Bayesian parameter estimation method and combined with limit states to derive the parameterized fragility curves. These fragility curves are used to develop bridge-specific and bridge-class fragility curves. Moreover, a stepwise removal process in the Bayesian parameter estimation is performed to identify significant parameters affecting component demands.     

Seismic Performance Assessment of Non-Compliant SMRF-Reinforced Concrete Frame: Shake-Table Test Study

Seismic performance assessment is carried out for reinforced concrete structure built in low-strength concrete lacking confining ties in beam-column joint. Shake-table tests were performed on 1/3rd scaled two-story frame using design-spectrum-compatible accelerogram, scaled to various target levels. The frame is observed with beam longitudinal bar slip and pullout. Joints with no confining ties experienced extensive damage, observed with cover/core concrete spalling. The frame could resist 70% of the design ground motion to remain within the code-specified drift limit. The code requirement for minimum column depth will not avoid joint damageability in case of low-strength concrete and joints lacking confining ties.     

Strength Hierarchy at Reinforced Concrete Beam-Column Joints and Global Capacity

Strength hierarchy assessment is a method that can be utilized to identify the weakest structural element at a reinforced concrete (RC) beam-column joint. The method was extensively used in various research activities at the University of Canterbury, which mainly involved beam-column joint subassembly tests. However, this method required improvements and refinements in order to be adopted in multi-story building applications. In this paper, the improvements made to the method are reported. In the improved method, capacity of the weakest element at every beam-column joint in an RC frame building can be related to the corresponding global base shear demand. The method has been illustrated via two example applications: an RC frame lacking joint shear reinforcement and a modern RC frame with adequate joint shear reinforcement. The case study examples confirmed the accuracy and the effectiveness of the method.