Behavior of Semi-Rigid Steel Connection for G+3 Symmetrical Structures under Consideration of Seismic Forces Civil Engineering Department

Prof. A.  C.  Umare; Ms. P.  S.  Madde; Ms. P.  D.  Veer; Ms. S.  R.  Surwase; Ms. R.  J.  Kamble

Behavior of Semi-Rigid Steel Connection for G+3 Symmetrical Structures under Consideration of Seismic Forces Civil Engineering Department

Analysis and Design of Semi-Rigid Steel Connections for G+3 Symmetrical Structures under Seismic Forces

by Prof. A. C. Umare*, Ms. P. S. Madde, Ms. P. D. Veer, Ms. S. R. Surwase, Ms. R. J. Kamble,

- Published in Journal of Advances and Scholarly Researches in Allied Education, E-ISSN: 2230-7540

Volume 15, Issue No. 2, Apr 2018, Pages 44 - 49 (6)

Published by: Ignited Minds Journals

ABSTRACT

As the Pinned Rigid connections does not provide true behavior of the structure so the connection called Semi-rigid connection are introduced in the structure by mean of joint spring stiffness to achieve the approximately real behavior of structure. In this paper analysis and design of top seat angle connection is presented and beam-column behavior for maximum deflection joint displacement are compared with different load combination.The results are taken from Staad-pro v8i and designed values are used to calculate relative spring stiffness of beam-column joint and applied on structure to get the semi-rigid type of connection and results are discussed for all three types of connections called pinned, rigid semi-rigid connection.

KEYWORD

semi-rigid steel connection, G+3 symmetrical structures, seismic forces, civil engineering, pinned connection, rigid connection, joint spring stiffness, beam-column behavior, maximal deflection, relative spring stiffness

1. INTRODUCTION

Steel structures are simple composite unit having different structural members such as beams; columns are so connected to one another with assumptions that the connections are either pinned or rigid connection. Pinned or Rigid connections are usually assumed for joint and support which provide simplifications in structural analysis and design but they neglect the true behavior of joint. To get true behavior of any joint in the structure the semi-rigid type of connection has to be introduced in the joint by taking spring stiffness of joint in account.

2. LITERATURE STUDY:

[2.1] Praveen Biradar, Dr. M.M. Awati(1)

In this paper joint stiffness is calculated and applied on the steel structure by means of software called STAAD-Pro & beam-column behavior is observed.

[2.2] Jared D. Schippers, Daniel J. Ruffley, Dr. Gian A. Rassati, Dr. James A. Swanson(2)

Top & seat angle bolted connection is design by considering the seismic factors on structure and practical models are checked for full and partial strength and the models are analyzed and validated in ABAQUS. Models are checked mechanically.

[2.3] A. Pirmoz, F.Danesh(3)

In this research finite element models are prepared using non-linear FEM and experimental testing are carried out to check the role of seat angle. Study carried out by considering the parameter as length of beam.

[2.4] A. Pirmoz, E. Mohammadrezapour (2008)(4)

In this research connection moment rotation response is studied under combined axial tension and monotonic moment using non-linear FEM analysis. Experimental models are tested mechanically.

3. LOADS APPLIED ON STRUCTURE:

Beam – ISWB 250 Column – ISLC225 FR with 3 mm gap. Bracing - TUB32322.6

1. Dead load A] Self weight of member = Applied through software. B] Floor Load > Self-weight of slab = 0.175*25 = 4.375 kN/m > Floor finishing & Ceiling finishes = 1.5 kN/m Total load= 4.375+ 1.5 = 5.875 kN/m > >6 kN/m 2. Live load = 2.5 kN/m 3. Earthquake loads: Seismic values are applied through software.

As per design results: Initial Stiffness of the connection[5] =Rki={3*Ia*h1^2/e0(e0^2+.78*ta^2)}

=544.1718464

Where, Ia =Moment of inertia = (le× ta3)/12 le= Length of angle provided h1=Centerline distance of web eo= Pitch of the bolt ta=Thickness of angle

Assumed load cases:- A] 1.2[D.L+L.L+EQ+x] B]1.2[D.L+L.L+EQ+z] Top and seat angle connection-symmetric model: Displacement in Pinned connection: 1] 5th generated load case [1.2 (D.L+L.L.EQ+x)] 2]6th generated load case [1.2D.L+L.L.EQ+z)] Fig no:5.1Fig no:6.1

Prof. A. C. Umare1* Ms. P. S. Madde2, Ms. P. D. Veer3, Ms. S. R. Surwase4,

column 111 & external column 182 Connected with Beam No. 197 for pinned connection: *Table 2: For Bottom nodes (54 & 46) of internal column 111 & External column 182 connected with Beam No. 84 for pinned connection: Displacement in Rigid connection: 5th generated load case [1.2 (D.L+L.L.EQ+x)] 6th generated load case [1.2 (D.L+L.L.EQ+z) *Table 3: For Top nodes (69 & 93) of Internal column 111 & External column 182 connected with beam No. 197 for Rigid connection: *Table 4: For bottom nodes (54 & 46) of internal column 111 & External column 182 connected with beam No. 84 for Rigid connection: Displacement in Semi-rigid connection

5th generated load case [1.2 (D.L+L.L.EQ+x)] 6th generated load case [1.2 (D.L+L.L.EQ+z) *Table 5: For top nodes (69 & 93) of Internal column 111 & External column 182 connected with beam No. 197 for Semi-rigid connection: *Table 6: For bottom nodes (54 & 46) of internal column 111 & External column 182 Connectedwith beam No.84 for Semi-rigid connection: Table no.7: Values of Maximum Deflection for Different Load Cases Behavior detail after observing above Result :- Loadcase5{1.2(DL+LL+EQ+x)}:

● Deflection in semi-rigid connection reduces by [(43.474-16.771)/43.474*100] 61.42% as per table-7 when compared with pinned connection results as shown in fig no.5.1for pinned connection &fig no.5.3 for semi-rigid connection. ● Deflection in Rigid connection reduces by [(43.474-15.490)/43.474*100] 64.36 % as per table-7 when compared with pinned connection results as shown infig no.5.1for pinned connection &fig.no.5.2 rigid connection. ● Deflection in semi-rigid connection increases by [(16.771-15.490)/16.771*100] 7.64%as per table-7 when compared with rigid connection

Prof. A. C. Umare1* Ms. P. S. Madde2, Ms. P. D. Veer3, Ms. S. R. Surwase4,

no.5.3 semi-rigid connection.

Loadcase6{1.2(DL+LL+EQ+z)}:

● Deflection in semi-rigid reduces by [(44.597-16.706)/44.597*100] 62.54% as per table-7 when compared with pinned connection results as shown in fig no.6.1for pinned connection &fig no.6.3 for semi-rigid connection. ● Deflection in Rigid connection reduces by [(44.597-15.758)/44.597*100] 64.66 % as per table-7 when compared with pinned connection results as shown infig no.6.1for pinned connection &fig.no. 6.2 forrigid connection. ● Deflection in semi-rigid connection increases by [(16.706-15.758)/16.706*100] 5.67% when compared with rigid connection as shown in fig no.6.2for rigid connection & fig. no.6.3 for semi-rigid connection.

Conclusion after comparing both load cases for maximum deflection when designed as top and seat angle connection [Symmetrical structure]:-

● When deflection is compared in semi-rigid and pinned connection for both load cases, it is observed that decrease in deflection in semi-rigid connection is more in load case 6 as compared to load case 5. ● Increase in deflection of semi-rigid connection is more in load case-5 is more as compared with load case 6. ● As the semi-rigid connection gives realistic behavior of structure and as per above results the semi-rigid connection is acting more ductile in nature compare to rigid connection so that it can be said that due to increase in the deflection in semi-rigid connection the collapse time of flexural member will increase. ● As the collapse time increases in connection it tends to provide more safety against the major lateral loads acting on structures like earthquake, wind forces, etc.

Table no.8: Beam-Column Joint Displacement Behavior [Symmetrical Structure] Result:- 1. For load case 5 (1.2*[DL+LL+EQ+x])

● As the pinned connection will be having free rotation at the joint the joint displacement in both external and internal beam-column joint is very high as compare to rigid and semi-rigid connection. The difference in beam-column joint displacement in internal column (111) & external (182) column are same which about [(42.739-13.566/42.739)*100] 68.25% increase in pinned connection when compared with the rigid connection. ● The difference in joint displacement in internal column (111) & external (182) column are same which is about [(42.739-14.782/42.739)*100] 65.41% increase in pinned connection when compared with the semi- rigid connection. ● External (182) and internal (111) beam-column Joint displacement increases by [(14.782-13.566)/14.782] 8.23% in semi-rigid connection.

2. For load case 6(1.2*[DL+LL+EQ+z])

● Joint displacement in both external and internal column is very high as compare to rigid and semi-rigid connection. The difference in joint displacement in internal column (111) & external (182) column are same which about [(43.985-13.442)/43.985*100] 69.44 % increase in pinned connection when compared with the rigid connection.

about [(43.985-14.415)/43.985*100] 67.22 % in pinned connection when compared with the semi- rigid connection. ● External (182) and internal (111) column Joint displacement increases by [(14.415-13.442)/14.415*100] 6.74 % in semi-rigid connection when compared with rigid connection.

Beam-column joint displacement result after comparing both load cases:-

● Beam-Column joint displacement is more in load case 6 as compare to load case 5 {[(43.985-42.739)/43.985]*100= 2.83%} which is about 2.83% more in load case 6 when designed as pinned connection. ● Beam-Column joint displacement is more in load case 5 as compare to load case 6 {[(13.566-13.422)/13.566]*100= 1.06%} which is about 1.06% more in load case 5 when compared with load case-6 for internal column & {[(13.558-13.456)/13.558]*100= 0.75%} about 0.75% more in load case 5 when compared with load case 6 for external column when designed as rigid connection. ● Beam-Column joint displacement is more in load case 5 as compare to load case 6 {[(14.782-14.415)/14.782]*100= 2.42%} which is about 2.42 % more in load case 5 when compared with load case-6 for internal column & {[(14.769-14.426)/14.769]*100= 2.32%} about 2.32% more in load case 5 when compared with load case 6 for external column when designed as semi-rigid connection.

4. REFERENCES:

A design procedure for bolted top & seat angle connections for use in seismic applications submitted byRassati, Dr. James A. Swanson AssociacaoBrasileira De Normastecnicas. Projeto de estruturas de concreto –Procedimento. – NBR 6118, Rio de Janeiro, 2003. Behavior of bolted top & seat angle connections under combined axial tension and moment loading submitted by Pirmoz, E. Mohammadrezapour (2008). Ferreira, M.A., El Debs, M.K., Elliott, K.S.DeterminacaoAnalítica da RelacaoMomento-RotacaoemLigacoesViga-Pilar de EstruturasPre-MoldadasdeConcreto. Haach, V. G. (2005). Analiseteorico-experimental dainfluencia da forca normal emnos de portico externosdeconcretoarmado. 2005. 159p. Dissertacao (Mestradoem Engenharia de Estruturas) – Escolade Engenhariade São Carlos, Universidadede Sao Paulo, São Carlos, 2005 Initial stiffness of Semi-rigid of Beam-to-column connection and structural internal force anlysis by Wang Yan, Liu Xiuli, Li Jianfen. The seat angle role on moment-rotation response of bolted angle connections submitted by Pirmoz, F.Danes The study of behavior of partially restrained connections under the effect of seismic load for top & seat angle connection submitted by Praveen Biradar, Dr. M.M. Awati

Corresponding Author Prof. A. C. Umare*

Assistant Professor, JSPM‘s ICOER, Wagholi, Pune E-Mail – akshay.umare91@gmail.com