建筑英文期刊及中英文翻译(3)

method, tension stiffening is a part of parametric study in non-linear analysis. With reference to this material model in Figure 3, tension stiffening curve parameter can be search at 0.0002 upwards (i.e. greater than 0.00018). Solution of NLFEA

The arc length method with iteration Modified Newton-Raphson (MNR) is used for the solution control of non- linear analysis. The analysis is required to reach the satisfactory solution parameters to accomplish the convergence. The parameter of the non -linear solution for this study as indicated in Table 2. During the load progressing, the analysis can terminate by controlling the maximum load parameter or the maximum displacement values. The maximum number of arc step in Table 2 is set to 50 since the actual arc step to complete the analysis to ultimate is not known initially. The initial load parameter is applied only at the

A-164

Proceedings of the 6th Asia-Pacific Structural Engineering and Construction

Conference (APSEC 2006), 5 ?6 September 2006, Kuala Lumpur, Malaysia

first step of analysis then the next load parameter will be increased automatically by Modified Newton-Raphson algorithm. The convergence tolerance must be specified for the analysis between steps as an error of solution.

RESULTS

NLFEA Output and Interpretation of Results

Basically in the NLFEA of reinforced concrete tall building structure, the outputs of principal stress are used to present the failure of concrete structures in compression and tension. Concrete crushing is achieved when the values of minimum principal stress, P3 exceed the compressive strength (i.e. 0.8 fcu) while concrete cracking is defined when the values of

maximum principal stress, P1 reached the tensile strength (i.e. 0.1 fcu). The tension cracking

direction is assumed to be perpendicular to the direction of the principal stresses, P1 while the crushing direction is assumed to be perpendicular to the direction of principal stresses, P3. Lateral Displacement

The load displacement response is presented in Figure 4. The maximum lateral displacement is 103 mm at node 2268, which located at the top level of model as indicated in Figure 7(b). The maximum load recorded is 59.17 KN at point A.

Proceedings of the 6th Asia-Pacific Structural Engineering and Construction Conference

(APSEC 2006), 5 ?6 September 2006, Kuala Lumpur, Malaysia

Principal stress in shear walls

The contours of the principal stress P1 representing the maximum tension (+ve maximum) and P3 representing the maximum compression (-ve maximum). The crushing strength adopted in this model is 0.8 fcu = 0.8 x 35 =28 N/mm2. Figure 5(a) clearly indicates the shear

wall start to crush at the corner of shear wall base (node 2286) with the compression stress of 28.45 N/mm2 (i.e. greater than 28 N/mm2 ).

Concrete crushing at step 21

Crushing area

Element

922

Node 2286

P3= - 28.45 N/mm2

Figure 5 Minimum principal stress contour diagram at the part of shear wall

base during concrete crushing at step 21

Principal stress in coupling beam

The stress contour and the deformed shape of coupling beam at level 1 are presented in Figure 6. The concrete cracking occur at the tension corner, node 3475 of element 1489 since step 15. The principle stress P1 was recorded at 4.106 N/mm2 which exceed 0.1??cu = 3.5 N/mm2 . It is a clear indication of the tension contour was induced diagonally at the mid span of coupling beam. Another observation is the compression stress at both corners of coupling beam was increased by increment of steps until the analysis terminated at step 32, the maximum compression stress achieved is 19.38 N/mm2 which is lesser than the crushing stress, 28 N/mm2 .

Concrete cracking at node 3475, element of 1489 with P1=4.106 N/mm2 (a)

Node 2419, P3=-19.38

N/mm2

(b)

Step 15

Diagonal tension evident at the mid span of coupling

beam. Cracking failure reached.

( P1 > 3.5 N/mm2 )

Step 31 Maximum compression of

coupling beam at corner. (node 2419 & node 3443)

Crushing failure was not occur in coupling beam. ( P3 < 28 N/mm2 )

Node 3443, P3 = -18.91 N/mm2

Figure 6 (a) Maximum principal stress contour for coupling beam at level 1;

A-166

Proceedings of the 6th Asia-Pacific Structural Engineering and Construction

Conference (APSEC 2006), 5 ?6 September 2006, Kuala Lumpur, Malaysia

DISCUSSION

Overall building behavior

The modified quarter model had improve the deform shape of overall tube in tube tall building as shown in Figure 7. The deformed shape yields double curvature deflections, which resemble a deformed shape of combine frame and shear wall.

Wind load

Quarter model Modified quarter Overall building ode 2268 model

Max Displacementdeflected as Overall building

cantilever deflected as double

curvature

.

(a) (b)

A

59.17KN

Wind load

Figure 7 (a) Deformation of quarter model (b) Deformation of modified quarter model The presented failure modes of tube in tube tall building had proved that the overall model behavior is definitely control by compression failure rather than tension. With the evidence of the principal stress in the critical compression zone indicating crushing occur at the shear wall base …… 此处隐藏：5627字，全部文档内容请下载后查看。喜欢就下载吧 ……