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1.
Motoi Yasumura Takahisa Kamada Yutaka Imura Motoi Uesugi Laurent Daudeville 《Journal of Wood Science》2006,52(1):69-74
Pseudodynamic (PSD) tests were conducted on two-level timber structures with plywood-sheathed shear walls, which each had
an opening of different configuration, to study the effects of the mechanical properties of the first and second levels on
the earthquake response of the structure. The specimens had two-level conventional post and beam frames that were 3 m wide,
3 m deep, and 6 m high with plywood sheathings nailed on one face of the structure. The first and second levels had different
opening configurations of window, door, or slit. Lateral forces were applied at the top of the first and second levels, calculating
step by step the next displacement based on the North-South (NS) components of the 1940 El Centro earthquake. The test results
were compared with those of the time-history earthquake response analysis using the lumped mass model and hysteresis model
presented in the companion article (part I). The experimental and simulated results showed that the simulation by means of
the lumped mass time-history earthquake response analysis predicted quite well the response of the first level, but tended
to underestimate the response of the second level, and that the PSD tests of an individual wall system with the mass supported
by that particular wall generally show a conservative estimate of the response. 相似文献
2.
Pseudodynamic (PSD) tests were conducted on plywood-sheathed conventional Japanese three-dimensional (3D) wooden structures.
Lateral load was applied to the edge beam of specimen structures to generate eccentricity loading. Specimens were based on
a combination of shear walls with openings in the loading direction and horizontal diaphragms with different shear stiffness.
The principle deformation of the horizontal diaphragm was torsion for rigid diaphragms and shear deformation for flexible
diaphragms. Lumped-mass time-history earthquake response analysis was conducted on the tested structures, and additional calculations
were conducted on structures with different eccentricity rates. Dynamic analyses were conducted by varying the masses and
the resistance of the walls in the loading direction. The simulated peak displacement response in the loading plane agreed
comparatively well with the PSD test results. The maximum displacement response on changing the wall resistant ratio showed
almost the same tendency as that obtained by changing the mass ratio up to an eccentricity rate of 0.3; however, the maximum
displacement response increased markedly beyond an eccentricity rate of 0.4. It was proved that the lumped-mass 3D model proposed
in this study was appropriate for conducting a parameter study on the 3D dynamic behavior of timber structures. 相似文献
3.
This article summarizes an experimental and numerical study on seismic behavior of wood-framed shear walls with an opening.
The objectives of this study were to compare the results of static and pseudodynamic tests of plywood-sheathed shear walls
with numerical simulation by the Finite Element (FE) model and to validate a finite element code EFICOBOIS for such an application.
This software is based on a macroelement approach to limit the number of degrees of freedom for the whole system. Nonlinear
laws for connections such as nails and hold-down connections, among others, are applied through macroelements that link plate
elements to beam elements. Numerical results obtained for the various loading conditions showed good agreement with the experiments.
Both static and dynamic computations are presented here.
Received: February 15, 2002 / Accepted: April 25, 2002
Correspondence to:M. Yasumura 相似文献
4.
Kei Sawata Masahiko Toda Satoru Kanetaka Yoshihisa Sasaki Takuro Hirai 《Journal of Wood Science》2011,57(6):536-541
When it is necessary to repair conventional Japanese wooden houses, the decayed lower parts of columns should be replaced
with new wood material. The bending resistance of columns repaired by four methods and the shear resistance of opening frames
with those repaired columns were investigated in this study. Bending tests of the repaired columns showed differences in initial
bending stiffness and maximum bending moment related to the repair methods and loading direction. Racking tests were conducted
on door opening frames with conventional door head members or upper partial walls sheathed with 12-mmthick plywood. The conventional
frame specimens broke at door head-column joints with no obvious bending deformation of the columns, resulting in little difference
in load-shear deformation curves among the repair methods. The columns of plywood-sheathed specimens, on the other hand, clearly
were bent after the nails at the plywood-to-wood frame joints started to pull off. The load-shear deformation curves of the
plywood-sheathed specimens did not vary regardless of the repair methods when shear deformations were small but were affected
by repair methods as shear deformation increased. 相似文献
5.
Jung-Kwon Oh Jung-Pyo Hong Chul-Ki Kim Sung-Jun Pang Sang-Joon Lee Jun-Jae Lee 《Journal of Wood Science》2017,63(1):45-55
A cross-laminated timber (CLT) wall plays the role of resisting shear stress induced by lateral forces as well as vertical load. Due to the press size, CLT panels have a limitation in size. To minimize the initial investment, some glulam manufactures wanted to make a shear wall element with small-size CLT panels and panel-to-panel connections and wanted to know whether the shear wall would have equivalent shear performance with the wall made of a single CLT panel. In this study, this was investigated by experiments and kinematic model analysis. Two shear walls made of small CLT panels were tested. The model showed a good agreement with test results in the envelope curve. Even though the shear walls were made of small panels, the global peak load did not decrease significantly compared with the wall made of a single CLT panel, but the global displacement showed a large increase. From this analysis, it was concluded that the shear wall can be designed with small CLT panels, but displacement should be designed carefully. 相似文献
6.
A sensitivity study was performed with a nonlinear elastic finite element model for monotonie analyses of wood-framed shear walls. The objective was to provide information about simplifying a model of wood-framed shear walls with no significant loss in accuracy. The simplifications concern features such as slips in joints between frame members, slips in hold-down connections, and bearing between adjacent sheathing panels. The results from analyses of a shear wall with an opening of window shape show that the effect of constraint by the bearing between sheathing panels and slips in frame joints on the overall stiffness of the wall is limited. Thus, there are great possibilities for reducing the calculation time by not taking these phenomena into account, avoiding an excessive number of degrees of freedom and iterations. The influence of the simplifications on the distribution of vertical reaction forces along the wall is more significant. Furthermore, if each simplification is introduced separately, the effect on the overall stiffness is greater. The difference, however, is less than 10%. The failing pattern of the nail connections is also clearly influenced by the simplifications when they are introduced separately. The results from the analyses show that slips in frame joints can be sufficiently represented by those in connection with the opening. 相似文献
7.
In a previous paper we presented the efficacy of the extended distinct element method (EDEM) on the collapsing process simulation of timber-frame structures. The results obtained were qualitative, and the need for quantitative simulation was pointed out. In this report, we improved our simulating programs with the aim of establishing a quantitative simulation by EDEM. For this purpose, the parameters of the frame members (beam or column) were determined by comparing the simulated results of four-point bending tests with experimental results. Other parameters of plywood and joint members were determined by simulations of two rail shear and slip tests of joint parts, respectively. Using these parameters we made simulations of the collapsing process of an actual-size plywood-sheathed wall and at the same time carried out the experiments under similar conditions. Simulated load–displacement curves of the plywood-sheathed wall were similar to those obtained in the experiments, and the sequence of failure at nailed joints of the simulation model gave good agreement with that of the experimental collapsing processes. Using these processes, we believe that we established a basic quantitative simulation method to test the collapsing process of timber-frame structures.Part of this paper was presented at the 52nd Annual Meeting of the Japan Wood Research Society, Gifu, April 2002; and at the 7th World Conference of Timber Engineering, Malaysia, August 2002 相似文献
8.
A half-scale model of a light-frame shear wall was developed to evaluate the racking performance of a fullscale shear wall (prototype). The effect of nail size on the performance of the shear wall was also investigated using models constructed with three types of nail. Materials for the model were determined through experimental methods, which included nail-head push-through, stud-to-sheathing nail connection, and static bending tests. Materials with which the model was made to be in similarity to the prototype were three-layer 4.8-mm plywood, 39.72-mm long nails, and 1 × 2 lumber cut from 2 × 4 studs. In accordance with ASTM E 72 and ASTM E 564, racking resistance tests were conducted on 20 shear walls. The results showed that the maximum load capacities of the prototype walls could be evaluated by the model without significantly different failure modes. Tests on the effect of nail size revealed that increasing the nail head diameter may improve the performance of shear walls.Parts of this paper were presented at the International Conference on Effective Utilization of Plantation Timber (ICEUPT'99), Chi-Tou, Taiwan, May 1999; and the World Conference on Timber Engineering (WCTE2000), Whistler, Canada, July–August 2000 相似文献
9.
The performance of plywood-sheathed shear walls is determined at the plywood-to-timber joints. In joints with dowel-type fasteners, such as nails and screws, the fastener is fractured under reversed cyclic loading (e.g., seismic force), reducing the ductility of the joint. The fracture is caused by low-cycle fatigue due to the reversed cyclic bending of the fastener. Therefore, evaluating the fatigue life is important for estimating the ultimate displacement. The main objective of this study is to estimate the ultimate displacement of the joints and to enable load–displacement calculation of single shear joints under reversed cyclic displacement when bending fatigue failure of the fastener occurs. Single shear tests were conducted under different loading protocols, and the damage performances of the fasteners were determined by subjecting them to reversed cyclic bending tests. Based on the results, the failure lifetimes of joints with dowel-type fasteners were estimated. In addition, the fracture mechanism of these dowel-type fasteners was elucidated. CN50-type nails and wood screws with dimensions of 4.1?×?38 and 4.5?×?50 mm were used as fasteners. The single shear tests showed that the smaller the displacements per cycle, the lower are the ultimate displacement and ductilities of the joints. Moreover, load–displacement relationship up to fastener failure can be approximately estimated by combining the yield model and failure lifetime. 相似文献
10.
In the previous report of this ongoing study, results of an extensive field survey were collated and a theoretical model was
proposed to predict the mechanical behavior of timber shear walls of traditional design in Taiwan. The initial objective of
the present report was to propose a simplified calculation method for estimating the initial stiffness and yield strength
of traditional timber shear walls. Based on the results of the field survey, a total of 15 full-scale specimens were tested
to verify the theoretical model and simplified calculation proposed previously. Good agreement was found from comparison of
analytical and experimental results. The results of this study show that the friction behavior between board units and beams
plays the major role in resisting the lateral force applied on the timber shear wall, followed by the resistance supplied
by embedment. The resistance provided by bamboo nails is minor due to the small section. Another trend found was that for
set dimensions of a timber shear wall, the board width can be increased to obtain higher stiffness and strength of the shear
wall. 相似文献
11.
Minghao Li Frank Lam Ricardo O. Foschi Shiro Nakajima Takafumi Nakagawa 《Journal of Wood Science》2012,58(1):20-30
This paper presents a structural model called “PB3D” to perform nonlinear time history analyses of post and beam timber buildings
under seismic loads. The model treats the three-dimensional structure as an assembly of roof/floor diaphragms and wall subsystems.
The roof/floor diaphragms are modeled by beam elements and diagonal brace elements in order to take into account the in-plane
stiffness. The wall system consists of vertical beam elements, for wall posts, as well as nonlinear shear springs to consider
the contribution of diagonal wall bracing members or sheathing panels. The hysteretic characteristics of the shear springs
are represented by a simplified, mechanics-based model named a “pseudo-nail”. Standard finite element procedure is used to
construct the system’s equation of motion, which is solved by Newmark’s integration. The model was verified against shake
test results of a three-story post and beam building subjected to strong ground motions scaled to the 1995 Kobe earthquake.
Model predictions agreed very well with the test results in terms of base shear forces and inter-story drift responses. This
model provides a robust and efficient tool to study the seismic behavior of post and beam timber buildings. 相似文献
12.
Okumu Gordon Wanyama Kei Sawata Takuro Hirai Akio Koizumi Yoshihisa Sasaki 《Journal of Wood Science》2012,58(4):315-321
In this study, an experimental study was conducted on the nailed timber–plywood–timber joints extended from the standard wall–floor joints of wooden light frame constructions, where the bottom plates of shear walls are nailed to the floors consisting of joists and floor sheathings nailed to them. The principal conclusions are as follows: The allowable lateral resistance of the nailed timber–plywood–timber joints can roundly be estimated by neglecting the plywood panels if their densities are higher than those of the timber main-members and they are fastened effectively onto the timber main-members. The stiffness of the timber–plywood–timber joints is less than that of the control timber–timber joints, which is improved by increasing the number of nails used to fasten the plywood panels onto the timber main-members. The stiffness of the joints whose floor sheathings are glued onto the joists is equivalent to the control timber–timber joints. The timber–plywood–timber joints with appropriate specifications have greater energy capacity until the failure than that of the control timber–timber joints. This ensures their energy capacity, which is important in dynamic resistance, to be equivalent to the control timber–timber joints. 相似文献
13.
The inter-storey drift limitations are meaningful reference values for structural seismic performance evaluation. This paper presents an analytical investigation into the seismic performance of multi-storey cross-laminated timber (CLT) structures to obtain the drift limitations under different earthquake hazard levels reasonably. The Pinching4 model was used to simulate the nonlinear mechanical behavior of three types of connections used in CLT structures, and a numerical model was further developed to capture the lateral load-resisting properties of CLT shear walls. Moreover, three benchmark multi-storey CLT apartment buildings were designed using the Equivalent Static Force Procedure according to National Building Code of Canada (NBCC), and simplified structural models were developed for these buildings. Depending on the results from numerous time-history dynamic analyses, the empirical cumulative distribution functions (CDFs) of the maximum inter-storey drifts were constructed for the three benchmark buildings. The probability of non-exceedance (PNE) of inter-storey drift thresholds under different earthquake hazard levels was proposed and validated. It is recommended that for low-rise CLT buildings within three stories, values of 0.30%, 0.75%, and 1.40% can be considered as the drift limitations for frequent, medium, and rare seismic hazard levels, respectively. For mid-rise or high-rise buildings without three stories, 0.25%, 0.70%, and 1.30% can be considered as drift limitations. 相似文献
14.
Effect of element type on the internal bond quality of wood-based panels determined by three methods
Three mechanical tests with different loading modes were conducted to evaluate the effect of element type on the internal bond quality of wood-based panels. In addition to the internal bond test, which is commonly used for mat-formed panels, interlaminar and edgewise shear tests were used to test oriented strandboard (OSB), particleboard, medium-density fiberboard (MDF) of two thicknesses, and plywood. The following results were obtained. Epoxy resin proved to be suitable for determining the interlaminar shear modulus instead of hot-melt glue. There was a linear relation between panel density and interlaminar shear modulus and a linear correlation between the interlaminar shear strength and internal bond (IB) strength for the mat-formed panels tested. OSB had the highest edgewise shear modulus, and MDFs had the highest edgewise shear strength in this study. The modulus/strength ratio also depended on both panel type and loading mode. The relation between the shear moduli determined from the edgewise and interlaminar tests indicated the characteristics of the shear properties of panels made of different elements.Part of this paper was presented at the Fourth International Wood Science Symposium, Serpong, Indonesia, September 2002 相似文献
15.
Wood-based panels are subjected to cyclic panel shear load caused by wind and seismic forces in such an application as the sheathing of bearing walls. The fatigue behavior of structural plywood under panel shear load with two different loading frequencies was examined. Pulsating panel shear load with a triangular waveform and loading frequency of 0.5 or 5 Hz was applied to the plywood specimens. Stress−strain hysteresis loops were measured throughout the fatigue tests. Fatigue life was highly dependent on loading frequency at more than 0.5 stress level. The deterioration of mechanical property and damage accumulation in plywood specimen was observed to be slower at higher loading frequency at more than 0.5 stress level. Analyses based on energy loss suggest that panel shear load with higher loading frequency causes less damage to the plywood specimen during one loading cycle at higher stress level, and that the fatigue damage accumulation causing failure might be dependent on stress level although it seems to be unaffected by loading frequency. Based on these results, a new fatigue failure model for plywood specimen was qualitatively developed by combining Weibull’s weakest link model and Daniels’ fiber bundle model. 相似文献
16.
Ciprian Pîrvu Hiroaki Yoshida Masahiro Inayama Motoi Yasumura Kinji Taki 《Journal of Wood Science》2000,46(3):193-201
In past years high priority was given to developing a seismic design for wood structures, including research on the response of wood structures to earthquakes. In this study a new type of portal frame with relatively large span was developed for the traditional Japanese wooden houses with large openings at the front to strengthen the structure. Stainless steel plates coated with zinc and glued with epoxy adhesives on laminated veneer lumber (LVL) members, composed of Douglas fir veneer and bonded with phenolformaldehyde resin, were used. The connection between the frame's beam and columns and between the columns and groundsills was mechanical, with bolts. The subject of this research was to analyze strength properties and failure behavior of glued LVL metal joints used as structural components and to evaluate the response of LVL portal frames under cyclic lateral loading. The results show that portal frames using glued LVL metal plates have a good multiplier for the shear walls and may be applied to traditional Japanese structures. The equivalent viscous damping provided good energy dissipation in the frames. The joints displayed good mechanical behavior during tests; moreover, the structures demonstrated high strength, stiffness, and ductility, which are necessary for a seismic design.Part of this paper was presented at the 47th annual meeting of the Japan Wood Research Society, Kouchi, April 1997; and at the 5th world conference on timber engineering. Montreux, Switzerland, August 1998 相似文献
17.
Wood-based panels such as plywood, oriented strand board, particleboard, and medium-density fiberboard are used for roof, wall and floor sheathing materials in residential construction. However, the service life of these panels is still unknown due to the lack of long-term durability data. In this paper, test results from six different indoor exposure experiments were integrated to investigate the long-term durability of wood-based panels. The indoor exposure tests lasted for a maximum of 10 years, providing the panels with the changes in moisture content that ranged between 5 and 18%. The reduction in mechanical properties was determined to be in the range of 0–16% for the bending strength, 3–22% for the modulus of elasticity, 11–31% for the internal bond strength and 0–8% for the nail-head pull-through strength. No reduction was recognized for the lateral nail resistance. Furthermore, the concept of deterioration intensity (DI) based on the moisture content history was introduced to predict the long-term durability of the panels, and various calculation methods for DI were discussed so as to increase the correlativity of this property with the reduction in a mechanical property. 相似文献
18.
19.
On mechanical behavior of traditional timber shear wall in Taiwan I: background and theory derivation 总被引：1，自引：0，他引：1
The objectives of this study were to explore the mechanical behavior of traditional timber shear walls in Taiwan and to propose
a theoretical model to predict their lateral force resistance. An extensive field investigation was conducted, and the dimensions,
tectonic detail, and materials used were recorded. The data collected were used as the reference for theoretical derivation
and experimental design. In the theoretical model, the moment resistance of entire shear walls was derived from the contributions
of the moment-resisting capacity supplied not only by embedment and friction action between board units and beams but also
the dowel action of bamboo nails. Timber shear walls with various geometric conditions and material properties are considered.
The theoretical model demonstrated in this study can be used to predict the mechanical behavior of timber shear walls and
will be verified by experiments in our next article. 相似文献
20.
In this study we tried to develop an analysis program that can simulate the collapsing process of timber-frame structures under dynamic loading by adopting the extended distinct element method (EDEM). Using the EDEM, it is possible to trace the movement of any parts that were separated from unity after the failure of connecting elements, a property that fits our purpose well. As a preliminary study, simple two-story frame structures were modeled and examined by our program. Each model is an assembly of frame members composed of the EDEM elements. The spring elements of the joints have less rigidity than those of the frame members. Several models were analyzed under dynamic loading. The models varied in the configuration of bracing shear walls. Experiments with a one-ninth model were carried out under similar conditions, and the results were compared with the results from numerical simulations. Simulated results showed various collapsing processes corresponding to the arrangement of the bracing shear wall, and the simulated aspects gave good agreement with the results of the experiments under similar conditions.Part of this paper was presented at the 50th Annual Meeting of the Japan Wood Research Society, Kyoto, April 2000 相似文献