Characterization of adobe wall structural systems for dynamic response

2016 ◽  
Author(s):  
◽  
Stephen Douglas Robert
Keyword(s):  
Failure Mode ◽  
Vacuum Chamber ◽  
Blast Resistance ◽  
Load Capacity ◽  
Compressive Load ◽  
Dynamic Responses ◽  
The World ◽  
Seismic Loadings ◽  
Sdof Analysis ◽  
Blast Loadings

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] Adobe building construction exists around the world. Most of the adobe structures are located in active seismic zones, and a considerable amount of research has been conducted on the seismic response of adobe structures. Protocols and standards for adobe structural analysis, design, and construction has been established to ensure quality assurance and structural stability. The vulnerabilities to seismic loadings have been established, and research and design of seismic retrofits for existing and new adobe construction have been conducted. The type of retrofit utilized can depend on the availability of materials, impact on the aesthetics of the structure, and region of the world that the structure exists. Very limited research exists on the structural response of these structures when subjected to an external blast load. This dissertation evaluates current adobe wall designs for blast resistance and provides recommendations for their blast retrofits. Although limited research has been conducted on the effect of blast loadings on adobe structures, it is possible that some seismic retrofit designs can be extended to enhance the blast resistance of adobe structures. The result would provide a multi-hazard retrofit that includes resistance to blast and seismic loadings. Research has been conducted to evaluate adobe blocks, adobe block component specimens, and adobe block walls. The adobe block testing provides material properties such as block compressive strength, modulus of rupture, shear strength, and mortar strength. These properties are important when analyzing the component and conducting wall testing research. The static adobe block-mortar bond shear strength and flexural strength of a column of adobe blocks subjected to bending were determined through research on adobe block component specimens. Research efforts also investigated the strength and failure modes of unreinforced and reinforced full-scale adobe block walls. Slender walls, referred to as wallettes, are the same height and approximately one-third the width of the full size adobe walls that were tested. The wallettes were tested in a four-point bending setup to determine the load capacity, deflection, and failure mode. The effect of wall thickness was determined by testing three unretrofitted wallettes of varying wall thicknesses of 10, 20¾, and 31½ in. A retrofit concept, with two variations, was applied to the 20¾-in. wallettes to determine their performance in increasing the load capacity, change the failure mode, and increase the stability of adobe block walls. The unretrofitted 20¾-in. wallette served as the baseline to evaluate the retrofitted wallettes. This research effort was extended to investigate full-scale unretrofitted and retrofitted adobe walls statically tested in a vacuum chamber. The vacuum chamber applies a uniform loading on the adobe block walls. A pretest compressive load was applied to the top of the wall and maintained during the test. The dead load of the roof that adobe walls typically support is represented by this compressive load, which is achieved through five 4×4 timber rafters that are connected to the top of the wall. Two unretrofitted and three retrofitted 10-in.-thick adobe block walls were tested. The loaddeflection curve and failure mode of the each wall were determined. Additionally, three unretrofitted 10-in.-thick adobe block walls were dynamically tested in a blast load simulator (BLS), located at the U.S. Army Engineer Research and Development Center (ERDC) in Vicksburg, MS, to determine the dynamic responses of adobe block walls to blast loadings. The walls were constructed with the same adobe blocks and mortar as in the static testing phase of the research, and a similar compressive load and system was used in the BLS tests. The experimental research will assist in developing blast resistant design methods for adobe walls and retrofits. The wallette tests results were analyzed to determine loaddeflection curves for the wallettes and if the curves could be used to assist in dynamic analyses of adobe walls of other thicknesses. The load-deflection curves gathered from the vacuum chamber provided experimental resistance functions for unretrofitted and retrofitted adobe block walls. Single-degree-of freedom (SDOF) analysis uses the resistance functions and can also be used to predict the responses of adobe walls to dynamic loads. The dynamic adobe block wall tests provide a reference of how well the SDOF analysis predicts the dynamic responses of adobe block walls. Additionally, the retrofit techniques provide guidance for retrofitting adobe block walls to sustain dynamic blast loads.

scholarly journals The concept of creating thrust based on angular momentum change

2021 ◽  
Author(s):  
Sergei Kupreev
Keyword(s):  
Angular Momentum ◽  
Vacuum Chamber ◽  
Loop Quantum Gravity ◽  
Low Energy ◽  
Practical Implementation ◽  
Material Body ◽  
The World ◽  
Classical And Quantum Mechanics ◽  
Physical Principles ◽  
Kinetic Moment

Abstract The change in the kinetic moment of a material body is considered regarding to classical and quantum mechanics. The possibility of creating the propulsion system in terms of energy efficiency exceeding the photon engine has been theoretically proved. The proposed new principle of motion is based on the law of conservation of angular momentum and is fully consistent with the basic fundamental laws of physics. It is proposed to use the emission/absorption of streams of low-energy particles with spin in the direction perpendicular to the movement of the material body. The practical implementation of this idea is confirmed by the presence of promising approaches to solving the problem of quantizing gravity (string theory, loop quantum gravity, etc.) recognized by the world scientific community and by the successful results of experiments conducted by the authors with the motion of bodies in a vacuum chamber. The proposed idea, the examples and experiments has given grounds for the formation of new physical concepts of the speed, mass and inertia of bodies. The obtained results can be used in experiments to search for elementary particles with low energy, to explain a number of physics phenomena and to develop transport of objects based on new physical principles.

Damage Mechanism Analysis of Carbon Fiber Composites under Compressive Load

2018 ◽  
Vol 775 ◽  
pp. 36-42 ◽  
Author(s):  
Xun Lai He ◽  
Jun Hui Yin ◽  
Zhen Qian Yang ◽  
Hong Wei Liu
Keyword(s):  
Carbon Fiber ◽  
Failure Mode ◽  
Fiber Composite ◽  
Testing Machine ◽  
Compressive Load ◽  
Damage Mechanism ◽  
Fiber Composites ◽  
Carbon Fiber Composites ◽  
Carbon Fiber Composite ◽  
Static Compression

Carbon fiber composite material with light weight, high strength, corrosion resistance and other characteristics of its impact damage mechanism is different from the traditional metal materials. In this paper, the quasi-static compression of carbon fiber composites was carried out by using a material testing machine to analyze the damage mechanism. The Hopkinson bar technology was used to test the dynamic mechanical properties. The damage mechanism of the carbon fiber composites under dynamic compressive loading was studied. Stress - Strain relationship of composites under Quasi - static and dynamic compressive load. It is found that the main failure mode of out-of-plane direction of carbon fiber composite laminates is brittle shear failure, while the in-plane failure mode shows the properties of brittle materials.

scholarly journals Exploring the Distribution of Blast Resistance Alleles at the Pi2/9 Locus in Major Rice-Producing Areas of China by a Novel Indel Marker

Plant Disease ◽  
2020 ◽  
Vol 104 (7) ◽  
pp. 1932-1938
Author(s):  
Dagang Tian ◽  
Yan Lin ◽  
Ziqiang Chen ◽  
Zaijie Chen ◽  
Fang Yang ◽  
...  
Keyword(s):  
Blast Resistance ◽  
Resistance Breeding ◽  
Field Trials ◽  
Indel Marker ◽  
Blast Disease ◽  
Cereal Crops ◽  
R Genes ◽  
Rice Varieties ◽  
Environment Friendly ◽  
The World

Rice blast disease caused by the fungus Magnaporthe oryzae damages cereal crops and poses a high risk to rice production around the world. Currently, planting cultivars with resistance (R) genes is still the most environment-friendly approach to control this disease. Effective identification of R genes existing in diverse rice cultivars is important for understanding the distribution of R genes and predicting their contribution to resistance against blast isolates in regional breeding. Here, we developed a new insertion/deletion (InDel) marker, Pigm/2/9InDel, that can differentiate the cloned R genes (Pigm, Pi9, and Pi2/Piz-t) at the Pi2/9 locus. Pigm/2/9InDel combined with the marker Pi2-LRR for Pi2 was applied to determine the distribution of these four R genes among 905 rice varieties, most of which were collected from the major rice-producing regions in China. In brief, nine Pigm-containing varieties from Fujian and Guangdong provinces were identified. All of the 62 Pi2-containing varieties were collected from Guangdong, and 60 varieties containing Piz-t were from seven provinces. However, Pi9 was not found in any of the Chinese varieties. The newly identified varieties carrying the Pi2/9 alleles were further subjected to inoculation tests with regional blast isolates and field trials. Our results indicate that Pigm and Pi2 alleles have been introgressed for blast resistance breeding mainly in the Fujian and Guangdong region, and Pi9 is a valuable blast resistance resource to be introduced into China.

Dynamics modeling and analysis of a four-wheel independent motor-drive virtual-track train

2020 ◽  
pp. 146441932096401
Author(s):  
Zhonghui Yin ◽  
Jiye Zhang ◽  
Haiying Lu ◽  
Weihua Zhang
Keyword(s):  
High Speed ◽  
Load Capacity ◽  
Dynamic Performance ◽  
Spatial Dynamics ◽  
Dynamic Responses ◽  
Dynamics Modeling ◽  
Dynamics Model ◽  
Coupling Effects ◽  
Dynamic Interactions ◽  
Modeling And Analysis

Due to urbanisation and the economic challenges of traffic, it is urgently necessary to develop an environmentally friendly virtual-track train with suitable speed, high load capacity and low construction cost in China. To guide the design and evaluate this train’s dynamic behaviour, a spatial-dynamics model has been developed based on the dynamics theory and tyre-road interaction. The proposed dynamics model comprises mechanical vehicle systems, traction and braking characteristics and tyre-road dynamic interactions. The coupling effects amongst those systems of virtual track train are derived theoretically for the first time. The nonlinear characteristics of the tyre are modelled by the transit tyre-magic formula with consideration of road irregularities. Based on a designed PID controller and the comprehensive dynamics model, the dynamic performance of the system can be revealed considering motion coupling effects and complicated excitations, especially under traction and braking conditions. The dynamic responses of whole virtual track train can be obtained by numerical integration under different conditions. The vibration characteristics of such train are assessed under running at a constant speed and during the traction/braking process. The results show that the vibrations of the vehicle system are significantly influenced by road irregularities, especially at high speed ranges. The motions and vibrations of different components are intensive coupled, which should not to be neglected in the dynamics assessment of the virtual track train. Besides, the dynamics model can also be applied to dynamics-related assessment (fatigue, strength and some damage conditions, et al.) and parameter optimisation of the virtual-track train.

PVCO Pipeline Performance Under Large Ground Deformation

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Brad P. Wham ◽  
Christina Argyrou ◽  
Thomas D. O'Rourke ◽  
Harry E. Stewart ◽  
Timothy K. Bond
Keyword(s):  
Polyvinyl Chloride ◽  
Large Scale ◽  
Ground Deformation ◽  
Load Capacity ◽  
Compressive Load ◽  
Soil Liquefaction ◽  
Compression Tests ◽  
Cross Sectional ◽  
Joint Rotation ◽  
Statistical Characterization

Technological advances have improved pipeline capacity to accommodate large ground deformation associated with earthquakes, floods, landslides, tunneling, deep excavations, mining, and subsidence. The fabrication of polyvinyl chloride (PVC) piping, for example, can be modified by expanding PVC pipe stock to approximately twice its original diameter, thus causing PVC molecular chains to realign in the circumferential direction. This process yields biaxially oriented polyvinyl chloride (PVCO) pipe with increased circumferential strength, reduced pipe wall thickness, and enhanced cross-sectional flexibility. This paper reports on experiments performed at the Cornell University Large-Scale Lifelines Testing Facility characterizing PVCO pipeline performance in response to large ground deformation. The evaluation was performed on 150-mm (6-in.)-diameter PVCO pipelines with bell-and-spigot joints. The testing procedure included determination of fundamental PVCO material properties, axial joint tension and compression tests, four-point bending tests, and a full-scale fault rupture simulation. The test results show that the performance of segmental PVCO pipelines under large ground deformation is strongly influenced by the axial pullout and compressive load capacity of the joints, as well as their ability to accommodate deflection and joint rotation. The PVCO pipeline performance is quantified in terms of its capacity to accommodate horizontal ground strain, and compared with a statistical characterization of lateral ground strains caused by soil liquefaction during the Canterbury earthquake sequence in New Zealand.

Blast test and numerical simulation of point-supported glazing

2016 ◽  
Vol 19 (12) ◽  
pp. 1841-1854 ◽  
Author(s):  
Suwen Chen ◽  
Chen-Guang Zhu ◽  
Guo-Qiang Li ◽  
Yong Lu
Keyword(s):  
Numerical Simulation ◽  
Failure Mode ◽  
Failure Modes ◽  
Blast Resistance ◽  
Polyvinyl Butyral ◽  
Laminated Glass ◽  
Curtain Wall ◽  
Blast Response ◽  
Glass Panels ◽  
Glass Curtain Wall

The blast resistance of point-supported laminated glass curtain wall has been investigated by means of field blast tests and numerical simulation. Nine site blast tests were carried out, considering two types of glass thickness and six TNT charges ranging from 0.4 to 30 kg. The overpressure and displacement time histories were measured and the failure modes were observed. The overpressure obtained from the measurement panel exhibited a typical pattern of near-field blast with a steep increase followed by a rapid decay within a few milliseconds. The displacement response of the laminated glass panels increased with the increase in the TNT charge almost linearly in the smaller tests (scaled distance ranging 4.5–7 m/kg1/3), which was in line with the increase in the blast impulse in these tests. The failure mode of the point-supported laminated glass panels was featured by tearing off of the polyvinyl butyral layer around the support area, while the glass shards still adhered to the polyvinyl butyral interlayer. Nonlinear dynamic finite element simulation agrees reasonably well with the results from the blast tests. Severe stress concentration has been predicted to occur at the rim of the support holes, leading to initiation of failure at these supports, and this also agrees with the failure mode observed from the blast test. Finally, parametric studies are carried out to investigate the influence of TNT charge weight and the geometric parameters of the panel on the blast response of the glass curtain wall.

The Stress Analysis of New Pressure Piping Model

2011 ◽  
Vol 474-476 ◽  
pp. 1215-1220
Author(s):  
Bin Wang ◽  
Cai Liu ◽  
Xue Li Wu ◽  
Xue Fei Qiao
Keyword(s):  
High Pressure ◽  
Load Capacity ◽  
Compressive Load ◽  
Theoretical Formula ◽  
Pressure Pipe ◽  
Unit Design ◽  
Pressure Pipeline ◽  
New Type ◽  
Pressure Unit ◽  
Development Tendency

High-pressure becomes the high pressure unit design main consideration factor to compressive load capacity, security, efficiency, economic and manufacturing process of high-pressure equipment. This article proposes a new pressure piping according to the current high-voltage device development tendency and the future requirement. This new type of pressure pipe can be simplified for pipe casing model. Firstly we establish single, double and multilayer pressure piping model. We push out the multilayer pressure pipe stress formula according to stress situation of the analysis of the knowledge of mechanics of each model. We get this pressure piping withstand by the most intrinsic pressure enhance obviously under each layer within the radius of the cylinder reach the initial limitation of materials and other parameters of model are same through the comparison of the theoretical formula calculation with other general. Pressure pipeline calculated value. The multi-layer pressure piping system's circum radius are smaller than other piping with other pressure piping withstand the same most intrinsic pressure and the most interior radius are the same situation.

Identification of Multi-Axial Seismic Loadings from Several Structural Dynamic Responses

2012 ◽  
Vol 204-208 ◽  
pp. 2483-2487
Author(s):  
Kun Zhang ◽  
Hui Li ◽  
Zhong Dong Duan ◽  
Siu Seong Law
Keyword(s):  
Degrees Of Freedom ◽  
Least Squares Method ◽  
Three Dimensional ◽  
Dynamic Responses ◽  
Frame Structure ◽  
Model Errors ◽  
Structural Dynamic ◽  
Seismic Loadings ◽  
Seismic Accelerations ◽  
Damped Least Squares

A new method is proposed to identify multi-axial seismic loadings from structural dynamic responses on limited degrees of freedom. The seismic loadings acting on structures are modeled by Hartley series approximation, and the sensitivities of structural dynamic response with respect to the unknown approximation coefficients are derived. The identification equation is set up based on best fitting structural measured and calculated responses, and is solved with the damped least-squares method. A five-story three-dimensional steel frame structure excited by El-Centro seismic accelerations is studied for validating the proposed method. Numerical simulations with measurement noise and model errors show that the proposed method can accurately identify all seismic loadings from only several responses of the structure.

scholarly journals Ultimate Limit Design of Strengthened Steel Columns by Mortar-Filled FRP Tubes

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Jian Hou ◽  
Li Song
Keyword(s):  
Failure Mode ◽  
Failure Modes ◽  
Load Capacity ◽  
Local Buckling ◽  
Ultimate Load Capacity ◽  
Composite Columns ◽  
Steel Columns ◽  
Frp Tube ◽  
Frp Tubes ◽  
Ultimate Limit

The present study investigated the various failure modes of strengthened steel columns by mortar-filled fiber-reinforced polymer (FRP) tubes to analytically formulate the ultimate capacities of these steel columns. A simple and effective method, wherein a mortar-filled FRP tube was sleeved outside the steel member, was also formulated to enhance the buckling resistance capacity of compressed steel members. In addition, to facilitate the connection of the column to other structural members, the length of the sleeved mortar-filled FRP tubes is less than that of the original steel columns. Theoretical analyses were also performed on the critical sections of such composite columns at their ultimate states to identify their potential failure modes, such as FRP-tube splitting at the ends or on the insides of wrapped areas, local buckling at the steel ends of transition zones, and global buckling of the composite columns. The corresponding ultimate capacity of each failure mode was then analytically formulated to characterize the critical failure mode and ultimate load capacity of the columns. The current theoretical results were compared with those from literature to validate the applicability of the developed ultimate limit design approaches for FRP-mortar-steel composite columns.

scholarly journals Maize Responses Challenged by Drought, Elevated Daytime Temperature and Arthropod Herbivory Stresses: A Physiological, Biochemical and Molecular View

2021 ◽  
Vol 12 ◽  
Author(s):  
Cristhian Camilo Chávez-Arias ◽  
Gustavo Adolfo Ligarreto-Moreno ◽  
Augusto Ramírez-Godoy ◽  
Hermann Restrepo-Díaz
Keyword(s):  
Climate Change ◽  
Global Climate ◽  
Direct Consequence ◽  
Environmental Stresses ◽  
Dynamic Responses ◽  
Plant Responses ◽  
Negative Effects ◽  
Maize Crop ◽  
The World ◽  
Insect Interactions

Maize (Zea mays L.) is one of the main cereals grown around the world. It is used for human and animal nutrition and also as biofuel. However, as a direct consequence of global climate change, increased abiotic and biotic stress events have been reported in different regions of the world, which have become a threat to world maize yields. Drought and heat are environmental stresses that influence the growth, development, and yield processes of maize crops. Plants have developed dynamic responses at the physiological, biochemical, and molecular levels that allow them to escape, avoid and/or tolerate unfavorable environmental conditions. Arthropod herbivory can generate resistance or tolerance responses in plants that are associated with inducible and constitutive defenses. Increases in the frequency and severity of abiotic stress events (drought and heat), as a consequence of climate change, can generate critical variations in plant-insect interactions. However, the behavior of herbivorous arthropods under drought scenarios is not well understood, and this kind of stress may have some positive and negative effects on arthropod populations. The simultaneous appearance of different environmental stresses and biotic factors results in very complex plant responses. In this review, recent information is provided on the physiological, biochemical, and molecular responses of plants to the combination of drought, heat stress, and the effect on some arthropod pests of interest in the maize crop.

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