scholarly journals Material characterization and structural response under earthquake loads of hakka rammed earth buildings

2021 ◽  
Vol 1 (1) ◽  
Keyword(s):  
Material Characterization ◽  
Structural Response ◽  
High Strength ◽  
High Volume ◽  
Outer Wall ◽  
Lateral Force ◽  
Rammed Earth ◽  
Timber Structures ◽  
Earthquake Loads ◽  
Wooden Structures

Hakka Tulou are rammed earth buildings that have survived material aging, natural weathering and earthquakes for hundreds of years. Previous paper has reported our observations and findings from nondestructive evaluations in field with focus on the integrity of the rammed earth outer walls and inner timber structures as well as the thermal comfort of living in these buildings [1]. This paper presents the structural response of Tulou buildings under earthquake loads using material data from field and employing finite element (FE) analysis program. The material characterization included scanning electron microscopy and compression strength/modulus of rammed earth samples and wall reinforcements, revealing their high strength and durability. The FE analyses were conducted on unreinforced Huanji Tulou as per the simplified lateral force analysis procedure defined by the Code ASCE-7 under three types of wall conditions: 1) unreinforced rammed earth outer wall only, 2) reinforced rammed earth outer wall without inner wooden structures, and 3) unreinforced rammed earth outer wall with inner wooden structures. The FE modeling revealed that the existing large crack in the outer earth wall of Huanji Tulou would not have developed under a strong earthquake load if the earth walls were reinforced. Furthermore, the high volume rammed earth wall integrated with inner timber structures would have offered the building unique earthquake resistance.

Structural Systems for Mass Timber Buildings

2019 ◽  
Author(s):  
Tim Gleason ◽  
Gordana Herning ◽  
John Klein
Keyword(s):  
Affordable Housing ◽  
Lateral Force ◽  
Timber Structures ◽  
Braced Frames ◽  
Conventional Concrete ◽  
Composite Systems ◽  
Lateral Resistance ◽  
Mass Timber ◽  
Story Building ◽  
Gravity System

<p>This paper investigates the design of lateral force resisting systems (LFRS) for multi-story mass timber structures in Boston, MA. Structural and environmental tradeoffs of replacing conventional concrete cores or steel braced frames with glue-laminated timber (GLT) braced frames are evaluated through numerical analyses of 8-, 12-, and 18-story building prototypes. Finding an optimal timber gravity system configuration is followed by examining lateral resistance of the prototypes. The resulting designs demonstrate a practical approach to assist designers in selecting a lateral system during the early stages of conceptual design. This research was conducted in parallel with a related study for implementation of mass timber in affordable housing in Boston, enabling a comparison between composite systems and all-timber structures.</p>

scholarly journals High Strength Al–V–M (M=Fe, Co or Ni) Alloys Containing High Volume Fraction of Nanoscale Amorphous Precipitates

1995 ◽  
Vol 36 (10) ◽  
pp. 1219-1228 ◽  
Author(s):  
Akihisa Inoue ◽  
Hisamichi Kimura ◽  
Kenichiro Sasamori ◽  
Tsuyoshi Masumoto
Keyword(s):  
Volume Fraction ◽  
High Strength ◽  
High Volume ◽  
High Volume Fraction ◽  
Ni Alloys

Influence of the Processing Variables on the Microstructure Evolution of a Bainitic Carbide-Free Steel

2016 ◽  
Vol 879 ◽  
pp. 867-872 ◽  
Author(s):  
M.C. Taboada ◽  
I. Gutiérrez ◽  
D. Jorge-Badiola ◽  
S.M.C. van Bohemen ◽  
F. Hisker ◽  
...  
Keyword(s):  
Retained Austenite ◽  
High Strength Steels ◽  
High Strength ◽  
High Volume ◽  
X Ray Diffraction ◽  
Tempered Martensite ◽  
Trip Steels ◽  
Volume Fractions ◽  
Advanced High Strength Steels ◽  
Processing Variables

New trends focused on achieving higher performance steels has led to a so-called 3rd Generation Advanced High Strength Steels (AHSS), in which the typical polygonal ferrite found in TRIP steels as a matrix phase is replaced by harder phases as Carbide-Free Bainite (CFB) and/or (tempered) martensite. Besides, large volume fractions of retained austenite (R.A.) with adequate stability are aimed for to improve the formability of the steels. Si containing steels are regarded as the most suitable to retard cementite formation and consequently reach high volume fractions of RA. In this work, CFB annealing schedules were applied to dilatometer samples of Fe-0.22C-2.0Mn-1.3Si. The overaging temperature TB was varied between 390 oC and 480 oC, and other processing variables investigated were the austenitizing temperature Taus, and the overaging holding time tB. The annealed samples analyzed with LOM, FEG-SEM, EBSD and X-ray diffraction techniques show that markedly different complex microstructures made up of bainite, ferrite, MA phase and retained austenite (R.A) are accomplished depending on the specific thermal cycle. These results are described in detail and discussed in relation to the dilatometry measurements.

An On-Going Monitoring Project of a New Timber Structure

2013 ◽  
Vol 778 ◽  
pp. 757-764 ◽  
Author(s):  
Francesca Lanata
Keyword(s):  
Structural Health Monitoring ◽  
Health Monitoring ◽  
Environmental Conditions ◽  
Environmental Changes ◽  
Construction Material ◽  
Structural Response ◽  
Timber Structures ◽  
The Real ◽  
Structural Health

Structural design, regardless of construction material, is based mainly on deterministic codes that partially take into account the real structural response under service and environmental conditions. This approach can lead to overdesigned (and expensive) structures. The differences between the designed and the real behaviors are usually due to service loads not taken into account during the design or simply to the natural degradation of materials properties with time. This is particularly true for wood, which is strongly influenced by service and environmental conditions. Structural Health Monitoring can improve the knowledge of timber structures under service conditions, provide information on material aging and follow the degradation of the overall building performance with time.A long-term monitoring control has been planned on a three-floor structure composed by wooden trusses and composite concrete-wood slabs. The structure is located in Nantes, France, and it is the new extension to the Wood Science and Technology Academy (ESB). The main purpose of the monitoring is to follow the long-term structural response from a mechanical and energetic point of view, particularly during the first few service years. Both static and dynamic behavior is being followed through strain gages and accelerometers. The measurements will be further put into relation with the environmental changes, temperature and humidity in particular, and with the operational charges with the aim to improve the comprehension of long-term performances of wooden structures under service. The goal is to propose new improved and optimized methods to make timber constructions more efficient compared to other construction materials (masonry, concrete, steel).The paper will mainly focus on the criteria used to design the architecture of the monitoring system, the parameters to measure and the sensors to install. The first analyses of the measurements will be presented at the conference to have a feedback on the performance of the installed sensors and to start to define a general protocol for the Structural Health Monitoring of such type of timber structures.

Numerical Modelling of Historic Vaulted Timber Structures

2013 ◽  
Vol 778 ◽  
pp. 517-525 ◽  
Author(s):  
Carina Fonseca Ferreira ◽  
Dina D’Ayala ◽  
Jose L. Fernandez Cabo ◽  
Rafael Díez
Keyword(s):  
Finite Element Method ◽  
Software Package ◽  
Structural Response ◽  
Shear Stiffness ◽  
Timber Structure ◽  
Structural Performance ◽  
Timber Structures ◽  
Global Response ◽  
Historic Structures ◽  
Numerical Approaches

Historic timber structures forming vaulted roofs of public and ecclesiastical buildings are present worldwide. The structural response of these constructions is usually governed by the structural performance of the joints, the interaction between the timber structure and the masonry parts, and the current condition of both joints and timber members. At present, numerical approaches, such as finite element method-based approaches are well-established tools for investigating the global response of complex historic structures. Using a FE-based software package, the authors developed a numerical model of a portion of an existing historic vaulted timber structure, which is part of the roof of the Cathedral of Ica in Peru, considering the in-plane semi-rigid response of the planked arches in the elastic range. For this purpose, the rotational and shear stiffness of the joints and the properties of the materials, which are assumed in good conditions, are calibrated by comparing the numerical outputs with experimental results available in literature. The aim of the work presented here is to compare the response of the same vault assuming either continuous (planks continuously connected) or discontinuous arches (modelling of the semi-rigid response of the joints which connect the planks together).

scholarly journals Utilization of Metakaolin and Calcite: Working Reversely in Workability Aspect—As Mineral Admixture in Self-Compacting Concrete

2018 ◽  
Vol 2018 ◽  
pp. 1-12
Author(s):  
Fatih Özcan ◽  
Halil Kaymak
Keyword(s):  
Compressive Strength ◽  
High Strength ◽  
High Volume ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Mineral Admixture ◽  
Self Compacting Concrete ◽  
Binder Ratio

In this work, utilization of metakaolin (MK) and calcite (C), working reversely in workability aspect, as mineral admixture in self-compacting concrete (SCC), was investigated. MK and C replaced cement in mass basis at various replacement ratios, separately and together. In total, 19 different SCCs were produced. Binder content and water to binder ratio were selected as 500 kg/m3 and 0.4, respectively. Workability tests including slump flow, T50, L-box, and V-funnel tests were performed. Consistency and setting times of binder paste were measured. While replacement of MK with cement increased the amount of plasticiser requirement, calcite worked reversely and decreased it. Reverse influence of MK and C on plasticiser requirement of SCC made possible to produce SCC at total 45% replacement ratio of MK and C together. Samples of SCC were cured in water at 20°C temperature. Compressive strengths of SCC samples were measured up to six months to evaluate the influence of MK and C, separately and together. Ultrasonic pulse velocity, abrasion, and capillary water absorption values of samples were determined at specified age. MK inclusion in concrete reduces workability, while C inclusion increases it. C and MK inclusion together remedied workability of concrete and enabled to produce SCC with high volume of admixtures. Furthermore, C incorporation increased one-day compressive strength, while MK incorporation reduced it in comparison with control concrete. In long term, C inclusion reduced compressive strength; however, MK inclusion increased it. C inclusion remedied one-day strength of concrete when it was used together with MK. MK inclusion remedied long-term compressive strength when it was used together with C and enabled to produce high-strength SCC with high volume of admixtures. SCC containing MK and C together showed better durability-related property.

Innovative UHS Steel Material for Tension-Only Braced CFS Walls

2021 ◽  
Vol 873 ◽  
pp. 25-31
Author(s):  
Alessia Campiche
Keyword(s):  
Seismic Energy ◽  
High Strength ◽  
Lateral Force ◽  
Creep Tests ◽  
Tension Tests ◽  
Steel Material ◽  
Steel Bars ◽  
Innovative Material ◽  
Cold Formed Steel ◽  
The University

Lightweight Steel (LWS) systems, made of Cold Formed Steel (CFS) profiles, are widespread in seismic areas and often preferred to traditional systems. Improving structural performances in order to have higher building is now the goal, which could be achieved thanks to the use of steel innovative material. In particular, to increase the seismic performances of CFS buildings, the University of Naples “Federico II”, in cooperation with the Italian company Lamieredil S.p.A., has developed an innovative Lateral Force Resisting System (LFRS). The LFRS mainly consists of CFS frame (studs and tracks) braced by “V” shaped pre-tensioned Ultra High Strength (UHS) steel bars. The bracing was designed to be able to limit global displacement of structure, working as elastic spring, and to dissipate seismic energy by yielding. In order to prove the effectiveness of the new system, an extensive experimental campaign has been conducted. This paper focuses on material and component tests, describing tension tests on traditional materials and UHS steel, creep tests on UHS steel and nut-bar assembly tests.

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