design process - suranaree university of...
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Reinforced Concrete DesignReinforced Concrete Design
Lecture 2 - Specification, Loads andDesign Methods
�� Structural Design ProcessStructural Design Process
�� Building CodesBuilding Codes
�� Working Stress DesignWorking Stress Design
�� Strength Design MethodStrength Design Method
�� Dead Load & Live LoadDead Load & Live Load
�� Load Transfer in Structure Load Transfer in Structure
Mongkol JIRAVACHARADET
S U R A N A R E E INSTITUTE OF ENGINEERING
UNIVERSITY OF TECHNOLOGY SCHOOL OF CIVIL ENGINEERING
ArchitecturalFunctional Plans
DesignDesign ProcessProcess
Select StructuralSystem
Trial Sections,Assume Selfweight
Analysis for internalforces in member
Member Design
Acceptable?Redesign
NG
Final Design& Detailing
OK
Design LoopDesign Loop
SpecificationsSpecifications
Developed by organizations such as AISC, ACIASCE, and EIT
Recommendations of good practice based onthe accepted body of knowledge
NOT legally enforceable
OrganizationsOrganizations
EIT = Engineering Institute of Thailand
ASCE = American Society of Civil Engineers
AASHTO = American Association of State Highwayand Transportation Officials
UBC = Uniform Building Code
BOCA = Building Officials & Code Administrators
ACI = American Concrete Institute
Building CodesBuilding Codes
���ก������ �������������� ก�� ��
Minimum requirements to protect the public
- �.�.�. ����� ����� 2522
- �����""��#ก���$� �����
- $%��""��#
Design Loads
Dead Loads - stationary loads of constant magnitude
Live Loads - moving loads or loads that vary in magnitude
Caused by the weight of structure
Include both the load bearing and non-load
bearing elements in a structure
Generally can be estimated with reasonable
certainty
�&�����ก����ก���� (Dead Load)
�&�����ก��/�ก0�/�������12
���������� kg/m3
���ก�������� �ก 2,400���ก��� ��� 2,320��� 500-1,200�� �ก 7,850
�������������� kg/m2
ก������� ���!" 14ก������� #�$%�&����' 50�� �ก��( ��, * ก�� 5
���������� 10-30���� 5����ก!""#$�"% 180-360����ก!""#$(�)"� 100-200
Tributary area = 0.5SL sq.m
Load on beam = 0.5wSL kg/m
Floor load = w kg/sq.m
LoadLoad from from PrecastPrecast Concrete SlabConcrete Slab
S
L
Example: Example: CPACCPAC Hollow Core Slab Hollow Core Slab HC100HC100
600 mm
100 mm
SLAB WEIGHT 296 KG/M2
PC WIRE 6 ∅ 4 MM.
SPAN 4 M.
LIVE LOAD 300 KG/M2
4 m
L : Beam span
w = ? kg/m
Floor Loads
Snow and Ice: 50 - 200 kg/sq.m.
Traffic Load & Pedestrian Load for Bridges
Impact Loads
Lateral Loads: Wind & Earthquake
�&������&�����กก����ก3�����ก3� ((Live LoadLive Load))
�&�����ก����ก3����6&������ก�ก������ ��� 6 (�.�. 2527) �.�.. ���������� �.�. 2522
������� �!"�#$"��%&������� '#"�(#)*�'#�ก+�(kg/m2)
(1) ����
(2) ก� ����������� ก���
(3) �����ก���� ������� � ��� ���� ! ������"#
(4) ����%&" �'ก%&"���()���ก���� ��)�� ����ก ���%�# %�*���� +,��-��.,���������
(5) �! �ก� 0 �
(6) (ก) ���2-)�3 �4" ,������%&" �'ก%&"���()������ก��2-)�3#�"-����� "-����� ������� %�*�������
(,) �����&� �� +� )4������- ,����)�� ����ก ���%�#�! �ก� %�*0 �
30
100
150
200
250
300
300
�&�����ก����ก3����6&������ (�0�)ก�ก������ ��� 6 (�.�. 2527) �.�.. ���������� �.�. 2522
������� �!"�#$"��%&������� '#"�(#)*�'#�ก+�(kg/m2)
(7) (ก) ��� �������- � ��7�*)�# ���#���� 8��������7�*)�# �����4 � �����( �����#���������#�����9�������ก:��&� �3 �������9�ก�� � �3
(,) �����&� �� +� )4������- ,�����2-)�3 #�"-����� "-����� %�*�������
(8) (ก) ����- � ���ก�< �-�-08�2=3 ��>9� ��3 ���� �����ก��#����-#�3 �����ก:���ก��%�*�����
(,) �����&� �� +� )4������- ,����� �������- � ����7�*)�# ��7�*)�# ���#���� 8���� �����#�� %�*���#��
(9) �����ก:�� �����,�������#���������#��
400
500
500
600
(10) ���9�������ก:��&�����ก�7�4
500
800
Wind LoadsWind Loads
��� ��� ก���*�ก�0���!�1��'�23103(ก���*�#�4���3�# ��� �ก53ก�65������
25.0 Vq ρ=
��7 � q = stagnation pressure ���3�# � (กก./�.2)
V = basic wind speed ������8� ��7)#9�#��3�� ����!:� 10 ��$� (ก�./=�.)
ASCE 7-98200483.0 VKq =
K = �>ก�$��?!*�'������!:��7 #�� $"��+�ก 10 ��$�
���ก"4 10 5010 < h < 20 8020 < h < 40 120#กก"4 40 160
����!:������ '#"�(��� �(��$�) (กก./$�.�.)
WIND DIRECTION
Windwardside
Leew
ard
side
0 m
10 m
20 m
30 m
Step wind loading
��� �$�� �.�.. ���������� �.�. 2522
��� 19 ��ก�������������ก ����������� ��� �������� ����������������ก ���� �������ก!��������"#$��"�� ���������������ก��� %ก&� ���� �"�$ ��ก����'(�� �'�����'������('�"�$ ��!�������'��"��()��
50(8) �� ���&#'��'&�ก����������'�'/0���� ��"����$�
40(7) �� ���ก��'&�ก����������'�'/0�
30(6) �� �������'&�ก����������'�'/0�
20(5) �� �������'&�ก����������'�'/0�
10(4) �� ����$��'&�ก����������'�'/0�
0(3) �� �������'&�ก����������'�'/0�
0(2) �� ����7����'&�ก����������'�'/0�
0(1) ����������'�'/0�
���ก� ������ก���ก�������������������������
ก��������ก�� ����
����������$���8 ����)�� %$ ��)�� %$ �����$%' ���$%' 8989:;�<= ��>&�� �= �����9���� ������ �%"���ก��$ �����&�'�����ก#�����"= ����&�ก������"= ����9'�����������ก��� %ก&��"#$��"�� %ก ��
Early 1900s: WSD was mainly used.
aci 318
ACI 318-56: USD was first introduced.
ACI 318-63: Treated WSD and USD on equal basis.
ACI 318-71: Based entirely on strength approach (USD)WSD was small part called Alternate Design Method (ADM).
ACI 318-77: ADM moved to Appendix AUSD was called Strength Design Method.
Building Code Requirements forStructural Concrete (ACI318-XX)and Commentary (ACI318R-XX)
ACI 318-95: Unified Design was introduced in Appendix B
ACI 318-05
ACI 318-83: ADM moved to Appendix B
ACI 318-89: ADM back to Appendix A
ACI 318-99: Limit State at Failure Approach was introduced
aci 318Building Code Requirements for
Structural Concrete (ACI318-XX)and Commentary (ACI318R-XX)
ACI 318-02: Change load factor to 1.2DL + 1.6LL
ACI 318-08
Reinforced Concrete
Design MethodsWorking Stress Design
(WSD)
Ultimate Strength Design(USD)
Limit State Design(LSD)
Performance-based Design(PBD)
ACI: Alternate Design Method
Stress fromservice load
Allowable stressFa
Concrete: Fa = 0.45f’c (ACI and "��.),= 0.375 f’c (�.�.�. "��#�� 2522)
Steel: Fa = 0.50Fy
- Design under service load condition
�#7���0��8�������� (Working Stress Design : WSD)
- Apply F.S. to strength of materials forallowable stress level Fa
Disadvantages of WSDDisadvantages of WSD::
-- Inability to deal with groups of loads where one loadInability to deal with groups of loads where one load
increases at a rate different from that of the others.increases at a rate different from that of the others.
-- Not account for the variability of the resistances Not account for the variability of the resistances and loadsand loads
-- Lack of any knowledge of the level of saftyLack of any knowledge of the level of safty
F.S. is not known explicitlyF.S. is not known explicitly
�#*+ก,�����-��. = Ultimate Stress Design (USD)
Design Strength Required Strength (U)≥
�#7�ก����� (Strength Design Method : SDM)
- Factored load condition = Structure is about to fail
(Ultimate load = �/,����ก(����ก�-��. )
- Apply F.S. in design via:
- Load factors (> 1.0)
- Strength reduction factors (< 1.0)
Dead Load Factor = 1.4
Live Load Factor = 1.7
Factored Load = 1.4 DL + 1.7 LL
Service Load = DL + LL
Required Strength (U) = Load Factors × Service load
= Factored Load
= �������ก��ก� ���
Load Factors
General:
U = 1.4 DL + 1.7 LL
Wind Load:
U = 0.75(1.4 DL + 1.7 LL+1.7W)
U = 1.05DL + 1.275W
Lateral Earth Pressure:
U = 1.4 DL + 1.7 LL+1.7H
U = 0.9DL + 1.7H
Factored Load Combinations
Strength reduction factor (φφφφ) :
Bending φ = 0.90
Shear and Torsion φ = 0.85
Compression φ = 0.70 or 0.75
Strength Reduction Factor = factor that account for
(1) Variations in material strengths and dimensions
(2) Inaccuracies in the design equations
(3) Degree of ductility and required reliability of member
(4) Importance of member in the structure
Nominal Strength (N) = Strength of a member calculated usingStrength Design Method.
Strength Reduction Factors
Load Transfer in StructureLoad Transfer in Structure
Floor loads
Slab + Dead loadRoof + Dead load
Snow, Rain, Windand Construction load
Column + Dead load
Wall load
Beam + Dead load
Foundation
Wind load
SoilEarthquake