Dynamic testing of two different timber wall.pdf

8/12/2019 Dynamic testing of two different timber wall.pdf

1/25

SHORT TERM SCIENT IFIC MISSION

University of LjubljanaFGG KPMK

Dynamic testing of two different

timber wall construction systems

Report of a Short Term Scientific Mission

to

IZIIS, Skopje Macedonia

within the frame of COST E29

Innovative Timber and Composite

Elements/Components for Buildings

Bruno Dujic

University of Ljubljana


2/25

SHORT TERM SCIENT IFIC MISSION COST E29

B. Duj ic Apr i l 2006 Page 2

Background of research activities

The new generations of lightweight, prefabricated structures are recentlybecoming more popular in European market. The new trends are bringing multistory

timber structures. Special attention is paid to buildings located in earthquake prone

areas of middle and south Europe. Therefore, the appropriate guidelines for designing

have to be set for existing and new timber structural systems to assure their seismic

resistance. The new European directives and standards (Construction Product

Directive, Eurocodes) are more demanding regarding to seismic resistance of structures

in seismic active European countries. Therefore, industry of prefabricated timber

structures should follow these demands if it would like to be present on worldwide

market of seismic areas.

In Slovenian construction practice a lot of attention is put on seismic design but till

now timber structures were ignored against other type of structures. The main reason

is that we manly built from other type of materials especially in concrete, steel and

family houses mostly from clay bricks. But nowadays new types of eco construction

systems are more and more present also in Slovenian regions.

Cooperation between research institutes

University of Ljubljana, Faculty of Civil and Geodetic Engineering (ULFGG) is last

few years oriented in seismic research of timber structures. Through research

activities ULFGG established strong connections with two important institutes and

research partners with specific knowledge on two different research areas. Partners

from Institute for Earthquake Engineering and Engineering Seismology from Skopje

Macedonia (IZIIS) are experts in seismic research and partners from MPA Stuttgart -

Otto Graf Institute (MPA) are experts in timber research. After very strong earthquake

which occurred in Skopje 1963, at IZIIS was installed one of the largest shaking

platforms in Europe. With some exchange visits and given lectures of researchers from

above mentioned institutions we set an outline of future research on evaluation ofseismic behavior of timber structures.

The execution of dynamic tests of four different timber models on shaking table at

IZIIS in Skopje, Macedonia is based on our own motivation and agreement between

collaborating research institutions to step forward on seismic research of European

types of timber buildings. With evaluation of their dynamic response parameters we

would like to clarify research needs for future research projects based on these

findings. With these research activities important contribution will be done in the

promotion of timber structures on seismic areas, especially in Slovenian and

Macedonian market, were timber structures were ignored against other type of


3/25



structures. The benefit of promotion will reflect also in ecological orientation of

investors, because nowadays more and more attention is paid on bio and ecological

aspects of chosen construction material, where wood has many advantages against new

and other conventional type of materials.

Previous research as starting point for present research activities

Within existing collaboration between MPA and ULFGG, the basic wall segments of

two different load-bearing systems of timber structures were already tested last year

at ULFGG. Tested wall panels of the first system were consisted from timber frames

with both sides sheathed gypsum fiber boards which were fixed to the frame with steel

staples. Further discussed tests of the second system are wall segments of solid cross

laminated wooden walls KLH panels. For the racking tests of the first system was

responsible Mr. Ruediger Finn from MPA, therefore this STSM report is concentrated

only on testing of the second system consisted from KLH panels.

Description of KLH panels

The basic material for production of cross-laminated solid timber panels is the

side-wood from trunk edge zones of spruce. For the production of cross-laminated

timber the technically dried timber with moisture of 12% (+/- 2%) is used. Pests, fungi

and insect attacks that may cause damage are thus excluded. Cross-laminated timber

is produced from spruce strips that are crosswise stacked on top of each other. Cross

lamination of the timber strips has many advantages. It minimizes swelling and

shrinkage in the board plane, considerably increases static strength and shape

retention properties and enables load transfer across the entire plane of panel.

The individual layers of wood are glued by the solvent-free and formaldehyde-free

polyurethane based adhesive Purbond HB 110 produced by Swiss company Collano. It

is tested according to DIN 68141 and other criteria of FMBA Baden-Wrttemberg, MPA-

Otto Graf Institute, Stuttgart. The adhesive is approved according to DIN 1052 and EN

301 for production of load-bearing timber building components and specialconstruction techniques, both for interior and exterior construction.


4/25



The boards undergo strict, visual quality

assortment. Depending on application or

load-bearing requirements, 3, 5, 7 or

more layers are stacked on top of each

other; up to a maximum thickness of 60

cm (Fig.1). Cross laminated panel - KLH

or in German language Kreuzlagenholz

is applicable for all construction parts in

structure as wall, floor or roof panel

(Fig.2).

Fig.1: Cross-laminated solid

wooden KLH panel.

Fig.2: Applicability of KLH panels for

different structural elements.

Racking tests of KLH wall panels

Racking tests were carried out on walls of length 244 cm and story height at

combined constant vertical load and monotonous or cyclic horizontal load applied

according to different loading protocols. Wall panels were tested at various boundary

conditions which enabled wall deformations from cantilever up to pure shear.

Influences of boundary conditions, magnitudes of vertical load and type of anchoring

systems were evaluated on the base of deformation mechanisms and racking strengths

of wall segments. Differences in mechanical properties between monotonic and cyclic

responses were studied.


5/25



At racking tests of wall diaphragms the main challenge was to simulate realistic

boundary conditions that may occur during the action of an earthquake. In reality, the

boundary conditions may change during an earthquake excitation because of changes

of the building characteristics due to development of damages. Therefore, the testing

device for quasi static cyclic testing should allow the altering of boundary conditions.

Which mechanism will be established during dynamic shaking of building depends on

combination of different parameters (shear stiffness of wall element, magnitude of

vertical load, stiffness and load-carrying capacity of anchors) and boundary condition

of wall installation into the structure; for example if the wall is fixed by metal

connections as in platform construction or up-lift of wall is constrained by frame

structure. Following this idea three major cases of boundary conditions are most likely

to appear in reality (Fig. 3):

shear cantilever mechanism, where one edge of the panel is supported by thefirm base while the other can freely translate and rotate (Case A);

restricted rocking mechanism, where one edge of the panel is supported by the

firm base while the other can translate and rotate as much as allowed by the

ballast that can translate only vertically without rotation (Case B) and

shear wall mechanism, where one edge of the panel is supported by the firm

base while the other can translate only in parallel with the lower edge and

rotation is fully constrained (Case C).

In Case A and Case B the panel is exposed to constant vertical load in every

stage of the cycling excitation or horizontal deformation induced along the upper edge

where the ballast is acting. In Case C the vertical load increases when the panel

tends to uplift due to displacements along the upper horizontal edge. In practice, the

Case A represents mostly the behavior of narrow panels and panels located in attic

and vertically loaded only by flexible roof constructions. The Case B is typical for

panels carrying the floor construction above it and the Case C is the typical case of

infill of a stiff surrounding frame.

The response of the tested wooden walls does not depend only on the boundary

conditions and the magnitude of vertical load but mostly on the configuration and

mechanical properties of the constituent elements and the assembly as a whole.

However, ignoring of the influence of different boundary conditions and the level of

vertical load may lead to miss-interpretation of the observed response. In Figure 1

three different patterns of wall behavior are presented: shear, rocking and combined

shear rocking response. All of them can develop under boundary conditions of shear

cantilever mechanism (Case A). The behavior depends on the shear stiffness of the

wall diaphragm as a whole, the magnitude of vertical load and the layout and

mechanical characteristics of the anchors. The shear response develops either if the


6/25



panel is flexible in shear or if the magnitude of the vertical force is relatively high.

The rocking response is typical for weakly anchored stiff panels or a low level of

vertical loading. Combined behavior can be observed in most cases of realistic

behavior of panels where different combinations of panel stiffness, anchoring and

vertical load take place. The response of panels tested with Case A boundary

conditions represents the conservative behavior. If the same panel is exposed to other

boundary conditions (Case B or Case C) the response values of rocking and

combined shear-rocking may be higher than the values observed using Case A

conditions. The reason therefore is the lowering of the tensile forces developed in the

vertical edges of the panel, consequently lowering the tensile loading of anchors.

Testing under conditions of the Case B is justified only when the behavior of the

panel in the real building is governed by an in and out of plane stiff floor diaphragm

(composite wood-concrete or solid wood slab). Testing under conditions of the Case

C is suitable for panels designed to act as frame infill, panels with glued-in-rods or for

highly vertically loaded walls in the lowest story of multistory buildings.

The results of testing under conditions of the Case C can not be considered

applicable to most realistic cases and may lead to serious mistakes if used wrongly in

the design of structures. Due to underestimation of the importance of the boundary

conditions the load bearing capacity of the panels is extremely overestimated

especially when the panels are loaded with vertical loads of low intensity or when the

panels are weakly anchored. However, at present the majority of known tests in

Europe and hereon based expertise and technical approvals are based on the Case C

conditions.

Case A: Rocking

response of walls

Case B: Combined shear

rocking response of wall

Case C: Shear response

of walls

Figure 3: Typical responses of wooden wall panels exposed to

combined vertical and horizontal load.

The complete information about the mechanical characteristics of wooden wall

panels and their anchoring can be obtained from responses both to monotonous and


7/25



cyclic loading with proper combination of vertical forces (Figure 3). The protocol of EN

594 is sufficiently covering the monotonous loading of wall panels. Unfortunately, the

protocol of EN 12512 covers only cyclic testing of particular joints made with

mechanical fasteners, what is an insufficient tool for evaluation of the behavior factor

q needed for design of earthquake resistant buildings. On the other hand, the ISO

16670 standard also addresses only the joints but the proposed protocol can be also

used for testing of wooden wall diaphragms. The reason therefore is that ultimate

joint displacement is used, instead of yield slip (EN 12512) which is difficult to define.

Since the ISO protocol is based on ultimate displacement it can forward a behavior

factor q as addressed in Eurocode 8.

The comparison of the responses of solid wooden panels subjected to cyclic and

monotonous loading (Fig. 4) well illustrates the importance of cycling testing. It was

observed that the load carrying capacity of the panel exposed to cyclic loading isbetween 10 to 20% lower than the resistance of the panel exposed to monotonous

loading. The cyclic response shows slightly higher initial stiffness due to hardening of

the fasteners exposed to low-cycle fatigue and lower ductility. Therefore, earthquake

design of wooden buildings can not be properly performed without data obtained from

cyclic testing of panels exposed to different intensities of vertical load.

-50

-40

-30

-20

-10

0

10

20

30

40

50

-60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60

Displacement at the top of the wall [mm]

HorizontalLoad

[kN]

cyclic horizontal load

EN 594 defined horizontal load

monotonous incrising horizontal load

Figure 4: An example of differences between monotonic and cyclic responses of solid

wooden wall panels with length of 2.44 m at vertical load of 15kN/m.

It is obvious that there is a need for development of an integral European standard

that would cover both monotonous and cyclic testing of wall diaphragms. The new


8/25



standard should also include the criteria for determination of limitations of inter-story

drifts according to the concept of performance based earthquake engineering design.

The graphs in Figure 5 reveal the influence of vertical load intensity both on the

load carrying capacity and the type of response mechanisms as discussed above and

presented in Figure 3. The characteristic of stiff solid wooden panels behavior is that

the shear mechanism does not develop in spite of varying boundary conditions from the

Case A to the Case B. It was reached when boundary conditions were set to the

Case C.

0

30

60

90

120

150

10 15 20 25 30 35

Vertical load per meter length of the wall [kN/m ']

Hor.loadcarringcapacity[kN]

Fmax (Case C)

Fy (Case C)

Fmax (Case A)

Fy (Case A)

BoundaryConditions - Case C

BoundaryConditions - Case A

Figure 5: Influence of vertical load intensity on load carrying capacity of

solid wooden wall panels with length of 2.44 m.

Dynamic tests of KLH models on shaking platform at IZIIS

Two full-scale models have been constructed and tested on the shaking table at

the IZIIS Laboratory, Skopje, Macedonia in order to investigate the response of massive

wooden wall panel systems under earthquake excitation. The basic idea was to make acorrelation between the results from the quasi-static tests already preformed at the

Laboratory of Faculty of Civil and Geodetic Engineering in Ljubljana and the results

from the shaking table tests. Comparative tests on structural segments with two

parallel walls of length 244 cm and story height linked together with slab timber panel

were performed in January and February this year. Dynamic tests were divided into

harmonic and seismic tests on two different KLH models. The main task of research

was to define mechanical properties of dynamic responses of tested models.

Dynamically developed failure mechanisms on wall segments could confirm reality of

proper boundary conditions set at racking tests executions. With establishing such


9/25


10/25


B. Duj ic Apri l 2006 Page 10

01.02.2006 - ambient vibration test on model with added mass

- comparison with the eigenvalue analytical results for verification

of the analytical model

02.02.2006 - instrumentation of the second model

- experimental determination of the natural frequencies of the

model (force vibration method)

03.02.2006 - sinusoidal dynamic tests with low amplitudes

- seismic tests: earthquakes with low and high maximal

acceleration peak

- sinusoidal dynamic tests with higher amplitudes until failure

- random vibration tests after each important seismic or dynamicexcitation for evaluating eventual damages of the second model

- inspection of damages on the model

04.02.2006 - removing instruments and masses from the second model

- removing tested model from the platform

06.02.2006 - collecting tools and instrumentation

- preparing tested elements for transportation back to Slovenia

07.02.2006 - departure and transportation of instrumentation equipment and

data acquisition system back to Ljubljana

till July 2006 All data evaluation will be done in June 2006 after my teaching

obligation at UL Faculty of Civil and Geodetic Engineering.

Complete processing of data of seismic and dynamic responses will be done until

July 2006 when the final report will be issued with evaluation of dynamic properties of

KLH system.

Description of KLH models

Two tested one storey models were made of KLH panels, product of Austrian

Company Massiveholz GmbH. Specimen 1 consisted of two one-unit wall elements of

dimension 244/272/9.4 cm and Specimen 2 consisted of two wall elements assembled

by screwing together two basic units of length 122 cm. Both models had a ceiling

element with dimensions of 244/210/16.2 cm and were stiffened by placing two more

panels 190.5/272/9.4 cm in lateral direction (Fig. 6 and 7). Solid wooden wall panels

are composed of three layers of cross glued lamellate wood. The tested wooden panels

of 244/272/9.4 cm have relatively high stiffness and load-bearing capacity. Therefore,


11/25



the critical elements that govern the wooden shear cantilever response to earthquake

excitations are anchors connecting wall panels with floor or building foundation.

Figure 6: Specimen 1 consisted of

two one-unit wall elements of

dimension 244/272/9.4 cm.

Figure 7: Specimen 2 consisted of two

wall elements assembled by screwing

two basic units of length of 122 cm.

Wall and floor panels are basically connected together with steel fasteners

(screws) and metal connectors in variety of configurations. Corner connectors are also

used for anchoring of wall panels into the building foundation. The main purpose of

herein reported research was to examine the properties of wall panel anchors and to

provide data to be used in design of earthquake resistant structures composed of KLH

walls. The research resulted in several improvements of structural system regarding

the modification of anchorages and usage of fasteners. The improvement mostly leadto substantial increase of ductility of structural assemblages and thus to more

desirable earthquake response of buildings composed of KLH elements.

In presented tests corner connectors of height of 105 mm with ribs were used and

placed on every 60 cm of wall length. For fixing corner connector to KLH wall panel 10

annularly nails 4,0/60mm were used and for fixing it to reinforced concrete foundation

beam two bolts M12 were used(Fig. 8).


12/25



Figure 8: Applied anchorage system.

The mass applied to the structure corresponds to 3-storey structure. Preliminary

estimations defined a mass of about 5 tons acting on a single wall panel with length of

244 cm representing ground floor wall of the considered building type. Following this

estimation and taking into consideration that each model consisted of two wall panels

and one roof panel additional mass of 9.6 tons was applied. Therefore 24 steel ingots

(3 layers by 8 ingots 400 kg each) were placed and connected rigidly to the roof KLH

panel (Fig. 9).

Figure 9: Top view of the applied mass to the model.


13/25



Shaking table installed at IZIIS

The shaking table on which the structural models were installed in order to be

subjected to a biaxial earthquake motion is a pre-stressed reinforced concrete panel

5.0 x 5.0 m in plan (Fig. 10). Four vertical hydraulic actuators located at four corners,

at a distance of 3.5 m in both orthogonal directions, with total force capacity of 888

kN, support the table. The total weight of the shaking table is 330 kN. The natural

frequency of the shaking table is 48 Hz for maximum loading mass placed in the center

of the table. The maximum applied accelerations are: vertical 0.50g and horizontal

0.70g with maximum displacement in vertical direction 0.050 m and in horizontal

direction 0.125 m. The frequency range is 0-80 Hz. In order to provide the required

power of the actuators three inter-connected hydraulic pumps with maximum flow of

1.250 l/min and a maximum pressure of 350 x 105 Pa are used. The gravity load due to

the table and the model mass is sustained by a special system, located in the lowerpart of each of the four vertical actuators, with static supports which utilize nitrogen.

The total bearing capacity for static loads is 720 kN. The horizontal and vertical

actuators of the table are supported by reinforced concrete rigid structure with a total

mass of 12.000 kN. The shaking system controls five degrees of freedom of the table,

two translations and three rotations. The analog control system controls

displacements, velocity, differential pressure and acceleration of the six actuators.

Reverse control is provided by three-variable servo control system, which is capable of

controlling displacements, velocities and acceleration simultaneously. A complete

package of computer programs for control and acquisition has also been used.

Figure 10: Display of the shaking table at IZIIS.


14/25



Instrumentation of the models

Figure 11 and 12 show the disposition of the measuring instruments for Model 1 and

Model 2.

For Model 1 for each of the wall panels, one LVDT was used to measure

displacement at the top edge of the wall panel, one LVDT was used for measuring the

slip between the wall and roof element, two LVDTs were measuring the diagonal

deformations, two were measuring uplift of the wall and one LVDT was used to

measure the slip between the wall element and the RC foundation.

For Model 2, for each of the wall panels, one LVDT was used to measure

displacement at the top edge of the wall panel, one LVDT was used for measuring the

slip between the wall and roof element, four LVDTs were measuring the diagonal

deformations, four were measuring uplift of the wall, one LVDT was used to measure

the slip between the wall panel element and the RC foundation, and two LVDTs were

measuring the slip between the two screwed single panels.

Five accelerometers were utilized in the dynamic tests: one accelerometer was

placed on the shaking table to check the input motion; two were placed on the

foundations to check weather any slip motion between the shaking table and the test

specimens exists and two were mounted at the top of both of the wall panel elements

in order to see whether any torsion appears. Table 2 and 3 give the detailed

description of the measured parameters and instruments designation for Specimen 1and Specimen 2 accordingly.

Table 2: Instrumentation of Model 1.

Designation Instrument - type Description

596, 597 LVDT displacement at the top edge

087, 088 LVDT slip between the wall and roof element

012, 014 LVDT vertical deformations

016, 019 LVDT vertical deformations

571, 572 LVDT slip between the wall and the RC foundation

343, 344 LVDT uplift of the wall

340, 341 LVDT uplift of the wall

454, 452 LVDT slip between shaking table and test specimen


15/25


16/25



Figure 11: Disposition of measuring instruments for R right and

L left wall panel of Model 1.


17/25



Figure 12: Disposition of measuring instruments for R right and

L left wall panel of Specimen 2.


18/25



Shaking table test program

After assembling the models on the shaking table and loading them with the ballast

the same test procedures were preformed for both of the tested specimens. Before

dynamic test execution ambient and forced vibration tests were performed to define

fundamental period of each model (Fig. 13). After damageable seismic and harmonic

test changing of fundamental periods of the tested models were estimated by random

vibration tests. Low-level random vibration tests were applied to measure if some

damage was occurred in the model.

Figure 13: The ambient and forced vibration tests to define fundamental periods.

Several seismic acceleration input motions were applied on the models with peakground acceleration increasing gradually from 0.06 g up to 0.55 g. In the next step the

models were subjected to harmonic excitation with frequencies of 7.5 Hz and 5.0 Hz.

After each earthquake and harmonic excitation, low-level random vibration tests were

carried out in order to monitor the change of the natural frequencies and eventual

damages on the models, what was impossible to recognize by visual inspection of the

model. Described test procedures for Model 1 and Model 2 have been summarized in

Table 4 and 5.


19/25



Table 4: Dynamic test procedure for Model 1.

Type of Test Description, Results

Ambient Vibration Tests Full Mass 9.6 tons;

7.4 Hz longitudinal, 3.4 Hz lateral, 15.8 Hz vertical,

9.6 Hz torsion

Forced Vibration Tests Full Mass 9.6 tons;

7.2 Hz longitudinal, 3.2 Hz lateral

Test Span* Acceleration of Platform

El Centro (x-component) 100 0.04 g

Petrovac (x-component) 100 0.06 g

Kobe JMA (NS-component) 100 0.09 g

Tolmezzo (x-component) 100 0.13 g

Albstadt (x-component) 65 0.27 g





Tolmezzo (y-component) 300 0.35 g







Petrovac (x-component) 250 0.19 gPetrovac (x-component) 550 0.37 g

Harmonic tests 7.5 Hz 10 45 (step 5)

Harmonic tests 5 Hz 15, 30 60 (step 10)

*Span is the 1/1000 of ultimate capacity of shaking table during the particular test run.

(span value of 100 means running of table at 10% of its ultimate capacity)


20/25



Table 5: Dynamic test procedure for Model 2.

Type of Test Description, Results

Ambient Vibration Tests Full Mass 9.6 tons;

7.4 Hz longitudinal, 3.6 Hz lateral,16.2 Hz vertical,

10.6 Hz torsion

Forced Vibration Tests Full Mass 9.6t; 6.8 Hz longitudinal

Test Span Acceleration of Platform

Albstadt (y-component) 65 0.18 g







Kobe (EW Component) 100 0.09 g





Harmonic Test 7.5Hz 10





Harmonic Test 5Hz 15



Harmonic Test 5Hz 50Harmonic Test 5Hz 60

Albstadt (y-component) 50

Albstadt (x+y component) 13h + 50v

Tolmezzo (y-component) 400 0.24 g


Tolmezzo (x+y ) 400h + 500v



21/25



Test results and discussion

Preformed test proved the non-linear behavior of the massive wooden wall panel

systems. The main source of the non-linearity is certainly the connection, i.e. the steel

anchorage system. The solid wooden wall panel itself behaves mostly linear-elastically

except around the contact area with mechanical fasteners where deformation of wood

fiber because of embedding stress perpendicular to fibers is present. For the cases

observed during the experimental tests, when the connections are much weaker parts

of the system than the wooden panel itself, the total dissipation of the energy and,

consequently, the total non-linearity comes from there. Therefore since the concept of

the seismic design is based on dissipation of the energy, in practice we will always

have panel elements, which are much stronger than the connections.

In Figure 14 some acceleration responses of different strong seismic excitationhave been compared. Amplification of acceleration at the top of the wall up to 0.62 g

was observed in Petrovac record where maximum acceleration reached at shaking

table was 0.37 g.

-0,8

-0,6

-0,4

-0,2

0

0,2

0,4

0,6

10 12 14 16 18 20 22 24 26 28

Time [s]

Accelerationatthetopofmodel[g]

Kobe_JMA_EW_700

ElCentro_850

Petrovac_550

Tolmezzo_300

Figure 14: Comparison of acceleration records measured

at the top edge of wall on Model 1.

From comparison of test responses different parameters will be set as influence of

connection details. On diagram in Figure 15 absolute displacement measured at the

tope edge of wall was compared as absolute response of Model 1 and Model 2.

Significant difference was observed as influence of vertical edge, where both wall

units were screwed together. On the base of comparison of relative displacements and

energy dissipation difference should be more clarified and defined.


22/25



-120

-80

-40

0

40

80

120

12 14 16 18 20 22 24 26 28

Time [s]

Absolutetopdisplacement[mm

]

abs_displ_M1

abs_displ_M2

Figure 15: Comparison of absolute horizontal moving of both models measured at the

top edge of the walls during the same seismic excitation El Centro (span 850).

In Figure 16 accelerations at basement level and at the top edge of walls of Model

2 are presented. Four measurements were done in longitudinal direction and one at

the top of wall in lateral direction. Excitation was harmonic with sinusoidal waves at 5

Hz with span 60. Fundamental frequency of the specimen was changed after all seismic

excitations because the cumulative damages. Therefore the excitation frequency was

close to the fundamental, as can be observed from acceleration records. The model

acceleration exceeds 100% of g in lateral direction. Although no visible damages were

observed, model behaved unevenly due to weakening of connections. Therefore,

substantial rotation was observed. Test run was stopped because ballast elements

(ingots) fixed atop of model started to move in lateral direction.


23/25



-125

-100

-75

-50

-25

0

25

50

75

100

0 1 2 3 4 5 6 7 8 9 10

Time [s]

Acceleration[%o

fg]

ACC_1 ACC_3

-100

-50

0

50

100

150

0 1 2 3 4 5 6 7 8 9 10

Time [s]

Acceleration[%o

fg]

ACC_2 ACC_4 ACC_5

Figure 16: Harmonic test with sinusoidal excitation of 5 Hz at shaking table span of 60

(6% of its capacity). Accelerations were measured on the basement level and at the

top edge of the walls in longitudinal and lateral directions.


24/25


25/25

SHORT TERM SCIENT IFIC MISSION COST E29In the scope of COST E29 action we are interested for exchange knowledge which

exist in Europe on seismic design of modern wooden structures and define some

outlines as research needs and future cooperation. The most important parameter in

seismic design is racking strength of load-bearing structure which is preloaded with

some magnitude of vertical load. Therefore there is still need to evaluate how

horizontal forces transmit through floor construction in different especially new

European systems of light timber structures. There is a question how stiff are those

floor constructions and if they could be taken into account as rigid compared to wall

rigidity or how semi rigid they are. In Europe massive wooden structures assembled

from cross laminated solid wooden panels becoming more and more popular. These

structures have good chance to be competitive with other type of structures also for

multistory buildings, if we define correct guidelines for design with proper and enough

dissipative elements as metal fasteners.

Acknowledgement

The COST E29 Management Committee and the representatives of COST Office are

gratefully acknowledged for their Short Term Scientific Mission grant, which contribute

to successful progress of this research work. In addition, local host Prof. Mihail

Garevski and his research team from IZIIS are thanked for their efforts and help during

my stay in Skopje, Macedonia. The research cooperation with IZIIS was enabled by the

bilateral Slovenian and Macedonian cooperation supported by Ministry of Science,

Higher Education and Technology of Republic of Slovenia.

Date post:	03-Jun-2018
Category:	Documents
Upload:	nodas2
View:	220 times
Download:	0 times

Dynamic testing of two different timber wall.pdf

Documents