One-year stress relaxation of timber joints assembled with pretensioned bolts

Awaludin, Ali; Hirai, Takao; Hayashikawa, Toshiro; Sasaki, Yoshihisa; Oikawa, Akio

doi:10.1007/s10086-008-0985-1

Cited by 13 publications

(8 citation statements)

References 10 publications

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“…In all specimens, a constant pretension of 20 KN was applied to bolts at the joint B so that lateral displacement of the vertical member due to rotation of the connection B can be minimized. Very large pretension should not be applied since wood beneath the steel plate would crush immediately and the amount of stress loss would be significant [12,13]. After performing the cyclic test, the joints were loaded monotonically until partial compression between the vertical and horizontal members takes place.…”

Section: Methodsmentioning

confidence: 99%

Beam to Column Timber Joints with Pretensioned Bolts

Awaludin¹,

Hirai²,

Sasaki³

et al. 2011

ced

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Abstract:The effects of pretension in bolts on hysteretic response of timber joints exposed to a bending had been reported by the authors, but the cyclic tests were carried out at small displacement level which might not be applicable for earthquake-resistance design. In this study, similar cyclic tests but at large displacement levels were conducted. Beam to column timber joints with steel side plates were fabricated and continuously loaded until failure. At connection, the bolts were pretension in four different magnitudes: 0 kN, 5 kN, 10 kN and 15 kN. The results showed that frictional action between the steel side plates and wood member as a result of bolt pretensioning significantly increased the (frictional) hysteretic damping and the equivalent viscous damping ratio. It is obvious from the test results that the pretension force in bolts has no influence on the maximum joint resistance but decreases the joint rotational deformation.

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Section: Methodsmentioning

confidence: 99%

Beam to Column Timber Joints with Pretensioned Bolts

Awaludin¹,

Hirai²,

Sasaki³

et al. 2011

ced

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“…Awaludin et al [3] examined the effect of the pretension force applied to the bolts used in moment-resisting joints and reported an increase in the initial rotational stiffness and hysteretic dumping in those joints. However, they also suggested that the initial prestressing effect must be considered negligible based on the results of the 1-year stress relaxation tests without restressing [4].…”

Section: Introductionmentioning

confidence: 99%

“…The relaxation behavior of the clamp force and controlling the clamp force are both considered in this study. When clamping is applied in the elastic region, the tightening torque method would generally be applicable [8,9]; however, it has been reported that the stress tends to disappear in that region [4,10]. Thus, we applied a form of displacement control by embedding a washer in the wood to control the clamp force.…”

Section: Introductionmentioning

confidence: 99%

Stress relaxation behavior of wood in the plastic region under indoor conditions

et al. 2019

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The stress relaxation behavior of wood in the plastic region was measured by clamping wood specimens with bolts for up to 5 years under indoor environmental conditions. An initial stress was applied by displacement control, whereby a steel plate or a washer was embedded in the radial direction of the wood. The difference in the stress ratio was small in the plastic region due to the difference in the initial stress level, and the higher the initial stress, the higher the stress that was maintained. By contrast, the clamp force virtually disappeared in the elastic region. The estimated stress ratio after 50 years was 15% in the elastic region and approximately 20-40% in the plastic region. Due to the influence of humidity fluctuation, it was difficult to maintain stress in the elastic region, but it seems to be possible to maintain the stress for a long time using partial plastic embedment with sufficient extra end distance.

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“…A number of research works have been undertaken on the improvement of cyclic performance of timber connections. [1][2][3][4][5][6][7] Hysteresis loops of conventional bolted timber connections are often characterized by pinching, or degradation of stiffness and strength under cyclic loading.…”

Section: Introductionmentioning

confidence: 99%

“…Hence the reduction of bolt tension due to shrinkage of glulam may lead to significant reduction of energy dissipating capacity. 7 Although the use of Belleville (cone disk) compression washers was proposed to avoid or minimize the reduction of bolt tension, its long term reliability is uncertain.…”

Section: Introductionmentioning

confidence: 99%

Feasibility of improved slotted bolted connection for timber moment frames

2011

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This note examines the feasibility of an improved slotted bolted connection for timber moment frames. In the present connection, steel tubes are inserted into drill holes in glulam, and the steel tubes are fixed to the glulam with resin injection. Aluminum splice plates with curved slots, or curved elongated holes, are fastened mechanically by using high strength bolts that go through the steel tubes. Since the compression due to bolt tension is fully supported by the steel tubes, reduction of bolt tension due to shrinkage of glulam can be avoided. The use of slotted aluminum splice plates allows stable energy dissipation due to smooth sliding between the aluminum splice plates and the end surfaces of the steel tubes within the specified range of rotation angle. Through quasistatic cyclic loading tests of two connection specimens, it was demonstrated that stable and nearly rigid-plastic hysteresis loops were obtained whose equivalent viscous damping ratio was more than 30 % in the ranges of rotation angle close to or over 1/50 radian. Although further improvement is necessary, the experimental results demonstrate the feasibility and potential of the present connection.

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One-year stress relaxation of timber joints assembled with pretensioned bolts

Cited by 13 publications

References 10 publications

Beam to Column Timber Joints with Pretensioned Bolts

Beam to Column Timber Joints with Pretensioned Bolts

Stress relaxation behavior of wood in the plastic region under indoor conditions

Feasibility of improved slotted bolted connection for timber moment frames

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