Collapse test columns

Frame members have additional criteria. Sidesway limits are applied to frame systems to reduce the chance of progressive collapse and to minimize P delta effects on columns. It is quite possible to maintain acceptable response of individual members but experience large lateral displacements of roofs and upper floors which cause collapse. The sidesway limits indicated in the tables are fairly liberal and should not be exceeded without detailed analysis or testing. 

A method for assessing foam stability in which one measures the rate of collapse of a (static) column of foam that has been generated by allowing a certain quantity of foaming solution to fall a specified distance into a separate volume of the same solution contained in a vessel. This technique is ASTM method D1173-53. See also Static Foam Test. 

Any of several methods for assessing foam stability in which one measures the rate of collapse of a (static) column of foam. See also Dynamic Foam Test, Foaminess. 

Fig. 10.4. Overall diagram of the operational zone of the time of the test (not to scale). At the bottom of the shaft, the container is surrounded by basalt sand. Above, the shaft is filled with cement and aggregates up to the top of the future collapse zone. The top of this zone corresponds to the base of the effective part of the stemming column. The container is linked by a cable harness to the recording barge, which transmits the...

Experimental Assessment of Foam Stability. Usually foam stability has been tested by one of three methods (4, 6, 13) (1) the lifetime of single bubbles (2) the steady-state (dynamic) foam volume under given conditions of gas flow, shaking, or shearing or (3) the rate of collapse of a (static) column of foam generated as described. 

In the last five columns we provide the values of the interfacial mobility parameter n (here n corresponds to power in t F R ), the predicted ratio of the surface viscosity coefficient ri and the critical collapse distance 6, the predicted individual values of ri and 6, and, where available, values of r] = K +e or obtained by direct methods. In the latter cases, the r data were obtained from a drop deformation method (17,18), and the e data from tests in a viscous traction instrument (20). 

Type J-BI-18 specimen has the bent in joint bar anchorage details with 18 mm diameter flexural reinforcement for beam and column. Figure 13.14 shows the load and displacement relationships for J-BI-18 specimen for both push and pull directions. Specimen J-BI-18 was designed for the beam flexural capacity of 137 KN. However, as shown in Fig. 13.14, it collapsed at 99 KN in a joint failure mode in shear. Figure 13.15 represents the formation of crack in joint during the cyclic load test. 

In these cases, it is deemed necessary to increase the column capacity under combined bending and axial load, aiming at turning the structure into a strong column-weak beam simation. The application of the hierarchy strength criterion implies an increase in the flexural capacity of columns and, thus, an increase of shear exerted at the nltimate states. As a consequence, snitable shear tests are required, eventually enhancing the strength towards this feature in order to avoid a brittle collapse. 

The European standard EC8-3 (CEN 2005) defines three Umit states, i.e. Umit states of damage limitation (DL), of significant damage (SD), and of near collapse (NC). The limit states are defined at the element level by the rotations in the moment - rotation relationship of the plastic hinge. In test examples presented in this paper only the probability of the exceedance of the NC limit state was evaluated. The NC limit state at the element level is reached when the rotation in plastic hinge exceeds the ultimate rotation, which corresponds to a 20% drop in strength. At the structure level, there is a lack of definitions of the limit states in codes. In this study, it has been conservatively assumed that the most critical column controls the state of the structure. Consequently, the structure is assumed to attain the NC limit state when the first column attains the NC limit state. Furthermore, it has been conservatively assumed that the NC limit state corresponds to the failure of the structure. The collapse of masonry infills does not influence the NC limit state. 

We considered the following problems to test the proposed method. The first one is the collapse of the liquid column. The liquid column is in the middle of the area at the initial time. Then column collapses under the influence of the gravity and movement of the entire medium takes place. The following hydrodynamic parameters were chosen here /xi = 10 , p = 10 for liquid and = 10 , P2 = 1 for gas. All the borders of area are solid. Fig. 1 and Fig. 2 show the appearance of the wave motion for two- and three-dimensional cases respectively. 

Zhu et al. (2007) provide an ultimate drift capacity model for two collapse modes. They considere a database of 125 nonconforming columns. Tests are divided in two different sub-databases according to a binary classification approach Zone S columns (shear-dominated failures) and Zone F columns (flexural-dominated failures). Zone F is composed of 85 tests, while Zone S is composed of 40 tests that include both... 

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