Nonlinear Connection Stiffness Identification of Heritage Timber Buildings Using a Temperature-Driven Multi-Model Approach

‘Que-Ti’ is an important component in typical Tibetan heritage timber buildings and it performs similar to corbel brackets connecting beam and column in modern structures. It transfers shear, compression and bending moment by slippage and deformation of components as well as limited joint rotation. A rigorous analytical model of ‘Que-Ti’ is needed for predicting the behavior of a timber structure under extreme loadings. Few researches have been done on this topic, particularly with the parameters describing the performances of this connection subjected to external loads. In this paper, a new temperature-driven multimodel approach is proposed to identify the stiffness parameters of a ‘Que-Ti’ connection in its operating environment. Models with nonlinear compression and rotational springs have been developed to take into account the change of mechanical behavior of the ‘Que-Ti’ affected by the temperature variation in typical heritage Tibetan buildings. The column–beam connection is modeled as two nonlinear rotational springs and one nonlinear compressive spring. Ambient temperature variation is treated as a force function in the input (temperature)–output (local mechanical strains) relationship, and stiffness identification is conducted iteratively via correlating the calculated strain responses with measured data. The nonlinear model of the joint is reproduced with a number of linear local models in different deformation scenarios that are corresponding to different temperature ranges. The stiffness parameters can be identified using a multimodel approach. Numerical results show that the method is effective and reliable to identify the nonlinear connection stiffness of the ‘Que-Ti’ accurately with the temperature change even with 10% noise in measurements. The monitoring data from a long-term monitoring system installed in a typical heritage Tibetan building is used to further verify the method. The experimental results show that the identified stiffness by the proposed method with nonlinear connection stiffness model can get better results than that obtained from the linear connection stiffness model.

Download Full-text

Field Test and Numerical Simulation on the Long-Term Thermal Response of PHC Energy Pile in Layered Foundation

Sensors ◽

10.3390/s21113873 ◽

2021 ◽

Vol 21 (11) ◽

pp. 3873

Author(s):

Guozhu Zhang ◽

Ziming Cao ◽

Yiping Liu ◽

Jiawei Chen

Keyword(s):

Thermal Conductivity ◽

Heat Exchange ◽

Temperature Variation ◽

Thermal Response ◽

Ground Temperature ◽

Short Term ◽

Energy Pile ◽

Backfill Soil ◽

Short And Long Term

Investigation on the long-term thermal response of precast high-strength concrete (PHC) energy pile is relatively rare. This paper combines field experiments and numerical simulations to investigate the long-term thermal properties of a PHC energy pile in a layered foundation. The major findings obtained from the experimental and numerical studies are as follows: First, the thermophysical ground properties gradually produce an influence on the long-term temperature variation. For the soil layers with relatively higher thermal conductivity, the ground temperature near to the energy pile presents a slowly increasing trend, and the ground temperature response at a longer distance from the center of the PHC pile appears to be delayed. Second, the short- and long-term thermal performance of the PHC energy pile can be enhanced by increasing the thermal conductivity of backfill soil. When the thermal conductivities of backfill soil in the PHC pile increase from 1 to 4 W/(m K), the heat exchange amounts of energy pile can be enhanced by approximately 30%, 79%, 105%, and 122% at 1 day and 20%, 47%, 59%, and 66% at 90 days compared with the backfill water used in the site. However, the influence of specific heat capacity of the backfill soil in the PHC pile on the short-term or long-term thermal response can be ignored. Furthermore, the variation of the initial ground temperature is also an important factor to affect the short-and-long-term heat transfer capacity and ground temperature variation. Finally, the thermal conductivity of the ground has a significant effect on the long-term thermal response compared with the short-term condition, and the heat exchange rates rise by about 5% and 9% at 1 day and 21% and 37% at 90 days as the thermal conductivities of the ground increase by 0.5 and 1 W/(m K), respectively.

Download Full-text

Comparative Analysis of Long-Term Subsurface Water Temperature Variation in Tokyo Bay, Kashima Coast and Kasumigaura.

Doboku Gakkai Ronbunshu ◽

10.2208/jscej.2000.656_239 ◽

2000 ◽

pp. 239-254 ◽

Cited By ~ 1

Author(s):

Hiroshi YAGI ◽

Kazuo NADAOKA ◽

Yusuke UCHIYAMA ◽

Hirofumi HINATA

Keyword(s):

Comparative Analysis ◽

Water Temperature ◽

Temperature Variation ◽

Subsurface Water ◽

Tokyo Bay

Download Full-text

Strength Performance of Steel Catenary Riser Using Short Term and Long Term Analysis Methodologies

Volume 5: Pipelines, Risers, and Subsea Systems ◽

10.1115/omae2016-54335 ◽

2016 ◽

Cited By ~ 1

Author(s):

Feng Wang ◽

Roger Burke ◽

Anil Sablok ◽

Kristoffer H. Aronsen ◽

Oddgeir Dalane

Keyword(s):

Bending Moment ◽

Current Profile ◽

Short Term ◽

Sea State ◽

Strength Performance ◽

Steel Catenary Riser ◽

Analysis Methodology ◽

Riser Design ◽

Term Analysis

Strength performance of a steel catenary riser tied back to a Spar is presented based on long term and short term analysis methodologies. The focus of the study is on response in the riser touch down zone, which is found to be the critical region based on short term analysis results. Short term riser response in design storms is computed based on multiple realizations of computed vessel motions with various return periods. Long term riser response is based on vessel motions for a set of 45,000 sea states, each lasting three hours. The metocean criteria for each sea state is computed based on fifty six years of hindcast wind and wave data. A randomly selected current profile is used in the long term riser analysis for each sea state. Weibull fitting is used to compute the extreme riser response from the response of the 45,000 sea states. Long term analysis results in the touch down zone, including maximum bending moment, minimum effective tension, and maximum utilization using DNV-OS-F201, are compared against those from the short term analysis. The comparison indicates that the short term analysis methodology normally followed in riser design is conservative compared to the more accurate, but computationally more expensive, long term analysis methods. The study also investigates the important role that current plays in the strength performance of the riser in the touch down zone.

Download Full-text

Load Combination for Fatigue Analysis of Ship Structures

23rd International Conference on Offshore Mechanics and Arctic Engineering, Volume 2 ◽

10.1115/omae2004-51582 ◽

2004 ◽

Author(s):

Yung S. Shin ◽

Booki Kim ◽

Alexander J. Fyfe

Keyword(s):

Bending Moment ◽

Linear Summation ◽

Load Combination ◽

Longitudinal Stiffeners ◽

Stress Components ◽

Tank Pressure ◽

Wave Induced ◽

Vertical Bending Moment ◽

Oil Tanker

A methodology for calculating the correlation factors to combine the long-term dynamic stress components of ship structure from various loads in seas is presented. The methodology is based on a theory of a stationary ergodic narrow-banded Gaussian process. The total combined stress in short-tem sea states is expressed by linear summation of the component stresses with the corresponding combination factors. This expression is proven to be mathematically exact when applied to a single random sea. The long-term total stress is similarly expressed by linear summation of component stresses with appropriate combination factors. The stress components considered here are due to wave-induced vertical bending moment, wave-induced horizontal bending moment, external wave pressure and internal tank pressure. For application, the stress combination factors are calculated for longitudinal stiffeners in cargo and ballast tanks of a crude oil tanker at midship section. It is found that the combination factors strongly depend on wave heading and period in the short-term sea states. It is also found that the combination factors are not sensitive to the selected probability of exceedance level of the stress in the long-term sense.

Download Full-text

Analysis of Ship Structural Loading in a Seaway

Marine Technology and SNAME News ◽

10.5957/mt1.1972.9.2.173 ◽

1972 ◽

Vol 9 (02) ◽

pp. 173-194

Author(s):

Dan Hoffman

Keyword(s):

Pressure Distribution ◽

Phase Relationship ◽

Bending Moment ◽

Green Water ◽

Detailed Structural Analysis ◽

Transverse Pressure ◽

Structural Loading ◽

Wave Induced

The recent advent of the large tanker and bulk carrier has promoted the requirements for more detailed structural analysis of a ship and the reevaluation of theories for calculating the static, quasistatic and dynamic loads. The paper begins with discussion of the methods available to determine the various types of loads expected, their phase relationship, and ways of superimposing them. It then proceeds to the treatment of sea loads based on theoretical and experimental data, and techniques of determining the ship response in a seaway are discussed. The response to regular waves is reviewed with special reference to the determination of pressure distribution on the hull. Statistical ship response, immediate and cumulative over the life of the ship, is demonstrated in relation to the prediction of long-term bending moment trends, and the distribution of the extremes is discussed. Special loading conditions are described with special emphasis on the transverse pressure distribution, dynamic effects due to motion of liquid cargo in tanks, shipping of green water, wave-induced vibrations, slamming pressures and whipping stresses due to various causes. The paper treats the above subjects in a broad manner and no attempt to illustrate the theory in detail is made.

Download Full-text

Long-term analysis of bending moment resistance on pre-cast concrete beams

Periodica Polytechnica Civil Engineering ◽

10.3311/pp.ci.2009-2.01 ◽

2009 ◽

Vol 53 (2) ◽

pp. 53

Author(s):

Kálmán Koris ◽

István Bódi

Keyword(s):

Concrete Beams ◽

Bending Moment ◽

Cast Concrete ◽

Term Analysis

Download Full-text

Some Climate-Altitude Relationships in the Southern Appalachian Mountain Region

Bulletin of the American Meteorological Society ◽

10.1175/1520-0477-40.7.352 ◽

1959 ◽

Vol 40 (7) ◽

pp. 352-359 ◽

Cited By ~ 3

Author(s):

R. R. Dickson

Keyword(s):

North Carolina ◽

Potential Evapotranspiration ◽

Growing Season ◽

Regression Equations ◽

Entire Area ◽

Mountain Valley ◽

Southern Appalachian ◽

Western North Carolina ◽

Temperature Ranges

The variation of certain climatic elements with elevation is examined for Tennessee-North Carolina portions of the Southern Appalachian region. Regression equations relating elevation to annual, January, and July mean temperatures and mean daily temperature ranges and to length of growing season are derived. Early growing-season data for 15 mountain-valley systems in western North Carolina are examined and regression lines developed relating length of growing season to elevation for valley and summit locations. These regression lines adjusted for departure of early data from long-term averages appear applicable to recent long-term data and present a useful means of refining the growing season-elevation relationship. Although a satisfactory precipitation-elevation relationship is unattainable due presumably to slope and exposure effects, an estimate is given of the mean annual snowfall-elevation relationship. Graphs are presented showing the variation of potential evapotranspiration with elevation based on computations for selected locations from 1075 ft to 6684 ft; results are believed representative of the entire area under consideration.

Download Full-text