Plane Frame Analysis Using the Stiffness Method
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Questions
In the stiffness method for plane frame analysis, which of the following represents the six load-displacement relations for a member in its local coordinate system?
View answer and explanationWhat is the purpose of the displacement transformation matrix, T, in the analysis of plane frames?
View answer and explanationHow is the member's global stiffness matrix, k, formulated using the local stiffness matrix, k', and the displacement transformation matrix, T?
View answer and explanationWhat does each column of the 6x6 global stiffness matrix k for a frame member represent?
View answer and explanationIn the 'Procedure for Analysis' for frames, how are the direction cosines lambda_x and lambda_y determined?
View answer and explanationIn Example 16.1, what are the direction cosines (lambda_x, lambda_y) for Member 1, which is horizontal and connects node 1 (at origin) to node 2 (at x=20, y=0)?
View answer and explanationIn Example 16.1, what are the direction cosines (lambda_x, lambda_y) for Member 2, which is vertical and connects node 2 (at x=20, y=0) to node 3 (at x=20, y=-20)?
View answer and explanationIn Example 16.1, with E = 29(10^3) ksi, I = 500 in^4, and L = 20(12) inches, what is the calculated value of the stiffness term 12EI/L^3?
View answer and explanationAfter solving for displacements in Example 16.1, the support reaction Q6 is calculated. The relevant row from the partitioned stiffness matrix is [0, -12.6, 1510.4, 0, 1510.4] and the displacement vector D is [0.696, -1.55(10^-3), -2.488(10^-3), 0.696, 1.234(10^-3)]. What is the value of Q6?
View answer and explanationWhat is the physical meaning of the internal loading q2 = 1.87 k calculated for member 1 at node 2 in Example 16.1?
View answer and explanationIn Example 16.2, why is the analysis for the frame in Fig. 16-5b later modified by the loads shown in Fig. 16-5c?
View answer and explanationIn Example 16.2, for Member 1, what are the calculated direction cosines lambda_x and lambda_y given its geometry?
View answer and explanationFor Member 2 in Example 16.2, which is horizontal, what are the direction cosines lambda_x and lambda_y?
View answer and explanationIn Example 16.2, the structure stiffness matrix is assembled. What is the value of the term K(2,2) in the final matrix?
View answer and explanationAfter solving the equations in Example 16.2, what is the calculated value for the displacement D2, which corresponds to the vertical displacement at node 2?
View answer and explanationWhat is the final bending moment at the right end of member 2 (node 3) in Example 16.2 after accounting for superposition?
View answer and explanationWhat are the three main types of data input required for a structural analysis program as described in the chapter?
View answer and explanationIn the general procedure for frame analysis using the stiffness method, which numbers are used to identify the unconstrained degrees of freedom?
View answer and explanationWhat does the 3x3 submatrix in the top-left corner of the local stiffness matrix k' (Eq. 16-1) represent?
View answer and explanationWhat is the correct relationship between the global forces Q, the local forces q, and the transformation matrix T?
View answer and explanationAccording to the final computed results in Example 16.2, what is the value of the support reaction Q5?
View answer and explanationIn the local stiffness matrix for a frame member (Eq. 16-1), what is the value of the coefficient relating the near-end moment (qNz') to the far-end rotation (dFz')?
View answer and explanationIn the 'Procedure for Analysis', what is the final step to compute the internal loadings q at the ends of the members?
View answer and explanationFor the inclined member in Example 16.2 with AE/L = 1160 k/in, 12EI/L^3 = 7.73 k/in, and direction cosines lx=0.8, ly=0.6, what is the value of the global stiffness matrix term k1(1,1)?
View answer and explanationWhat does a negative sign on a calculated unknown quantity, such as a displacement or reaction, indicate in the stiffness method analysis?
View answer and explanationIn Example 16.1, after calculating support reactions, Q8 is found to be 1.87 k. What does this value represent physically?
View answer and explanationIn the general expression for the global stiffness matrix of a frame member (Eq. 16-10), what does the element k(3,1) represent?
View answer and explanationThe final assembled structure stiffness matrix K, as seen in Examples 16.1 and 16.2, should always have what property?
View answer and explanationIn the local stiffness matrix for a frame member (Eq. 16-1), what is the value of the coefficient relating the near-end axial force (qNx') to the far-end axial displacement (dFx')?
View answer and explanationWhat is the final vertical shear force at the left end of member 2 (node 2) in Example 16.2 after accounting for superposition?
View answer and explanationIn the displacement transformation matrix T for a plane frame member (Eq. 16-3), what does the element T(2,1) represent?
View answer and explanationIn the force transformation matrix TT (Eq. 16-5), what does the element at row 1, column 2, represent?
View answer and explanationWhat is the primary reason for extending the analysis of beams to frames using transformation matrices, as mentioned in the introduction to Chapter 16?
View answer and explanationIn Example 16.1, what is the value of the internal axial force in member 2?
View answer and explanationIn the local stiffness matrix for a frame member (Eq. 16-1), what does the coefficient k(2,5) represent?
View answer and explanationBased on Example 16.2, what is the value of the term 4EI/L for Member 1, where L=25(12) inches, E=29(10^3) ksi, and I=600 in^4?
View answer and explanationIn Example 16.2, a 3 k/ft distributed load over 20 ft on the horizontal member is replaced by equivalent end moments and shears. What is the value of the equivalent end moment?
View answer and explanationAfter computing the displacements in Example 16.2, what is the final calculated support reaction Q7?
View answer and explanationFor the horizontal member (Member 2) in Example 16.2, with L=20(12) in, E=29(10^3) ksi, and I=600 in^4, what is the value of the stiffness term 12EI/L^3?
View answer and explanationHow is the internal loading `q` for member 1 computed in the final step of Example 16.1?
View answer and explanationWhat is the primary difference between a plane frame member and a plane truss member in the context of stiffness analysis?
View answer and explanationIn Example 16.1, what is the calculated value of the support reaction Q9?
View answer and explanationIn Example 16.2, what does the value -1200 in the Qk vector represent?
View answer and explanationWhat does the term k(6,6) in the local stiffness matrix for a frame member (Eq. 16-1) represent?
View answer and explanationFor the inclined member (Member 1) in Example 16.2, with lx=0.8, ly=0.6, and 6EI/L^2 = 1160 k, what is the value of the global stiffness matrix term k1(3,2)?
View answer and explanationWhat is the physical interpretation of the displacement D3 = -0.00217 rad calculated in Example 16.2?
View answer and explanationIn the general expression for the global stiffness matrix (Eq. 16-10), what is the formula for the term k(4,1), which relates the far-end x-force to the near-end x-displacement?
View answer and explanationBased on the FBD for member 2 in Figure 16-4d, what is the internal shear force at the bottom end (node 3)?
View answer and explanationIn the displacement transformation matrix T (Eq. 16-3), what is the value of the element T(3,3), which relates local rotation dNz' to global rotation DNz?
View answer and explanationWhat is the final horizontal reaction at the support at node 1 in Example 16.2?
View answer and explanation