Project

Reinforced Concrete Beam Design Review Project

Civil engineering project for a reinforced concrete beam design review, including load cases, moment and shear demand, reinforcement sizing, serviceability, detailing, construction evidence, and approval deliverables.

Branch: Civil and Construction Engineering
Content: Project
Updated: Jun 22, 2026
Revision: v1.0.0 · reviewed

This project produces a reinforced concrete beam design review package. The deliverable is not just a calculation sheet. It is an engineering review that connects loads, beam actions, concrete and reinforcement behavior, detailing, construction evidence, serviceability, durability, and approval conditions.

The project is intentionally simplified for education. It is not a substitute for the governing structural code, a licensed design, seismic detailing rules, fire design, progressive-collapse review, or project-specific specifications. Its purpose is to show how engineers turn a preliminary beam calculation into a traceable design-review package.

The central project question is:

Can the proposed reinforced concrete beam carry the required loads with credible flexural capacity, shear capacity, serviceability performance, detailing, and construction evidence?

The correct review answer is conditional. A beam can satisfy the arithmetic and still fail review if the reinforcement cannot be placed, developed, inspected, protected from corrosion, or verified during construction.

Project Objective

Prepare a design review for an interior reinforced concrete floor beam. The package must include:

design basis and assumptions;
load takeoff and factored load combination;
shear and bending demand;
flexural reinforcement sizing;
shear reinforcement review;
serviceability deflection check;
detailing and constructability checks;
construction inspection evidence;
residual risks and approval conditions;
final review deliverable.

The result should be suitable for a preliminary engineering review, not final construction authorization.

Design Basis

The simplified beam supports a one-way slab strip in a building floor. The beam is treated as simply supported for the review model.

Quantity	Value
clear span used for review	$L=6.0\ \text{m}$
tributary slab width	$b_t=3.0\ \text{m}$
beam width	$b_w=300\ \text{mm}$
overall beam depth	$h=600\ \text{mm}$
effective depth to tensile steel	$d=540\ \text{mm}$
concrete compressive strength	$f'_c=30\ \text{MPa}$
longitudinal reinforcement yield strength	$f_y=500\ \text{MPa}$
stirrup yield strength	$f_{yv}=500\ \text{MPa}$
nominal interior exposure cover target	$40\ \text{mm}$
assumed flexural strength factor	$\phi_f=0.90$
assumed shear strength factor	$\phi_v=0.75$

Use the following unfactored area loads:

Load component	Value
slab, finishes, ceiling, services	$4.5\ \text{kPa}$
live load	$3.0\ \text{kPa}$
reinforced concrete unit weight	$24\ \text{kN/m}^3$

Use the simplified strength load combination:

w_u=1.2D+1.6L

Use service load for the deflection screen:

w_s=D+L

The notation here is educational. The governing standard may require different load factors, pattern loading, live-load reduction, long-term deflection multipliers, seismic combinations, fire cases, robustness checks, and minimum detailing requirements.

Load Takeoff

Dead load from the supported slab strip is:

w_{D,slab}=q_D b_t

w_{D,slab}=4.5(3.0)=13.5\ \text{kN/m}

Beam self-weight is:

w_{D,beam}=b_w h \gamma_c

Convert dimensions to metres:

b_w=0.300\ \text{m}

h=0.600\ \text{m}

Then:

w_{D,beam}=0.300(0.600)(24)=4.32\ \text{kN/m}

Total dead load on the beam is:

D=13.5+4.32=17.82\ \text{kN/m}

Live load is:

L=3.0(3.0)=9.0\ \text{kN/m}

The strength design line load is:

w_u=1.2(17.82)+1.6(9.0)

w_u=35.78\ \text{kN/m}

The service line load is:

w_s=17.82+9.0=26.82\ \text{kN/m}

The first review point is that self-weight is material. It contributes almost one quarter of the total dead load. Omitting it would understate both moment and shear.

Beam Actions

For a simply supported beam with uniform factored load:

\displaystyle V_u=\frac{w_uL}{2}

\displaystyle M_u=\frac{w_uL^2}{8}

Factored end shear:

\displaystyle V_u=\frac{35.78(6.0)}{2}=107.3\ \text{kN}

Factored midspan moment:

\displaystyle M_u=\frac{35.78(6.0)^2}{8}=161.0\ \text{kN m}

These are design effects from a simplified model. A real review should also check continuity, support fixity, pattern live loading, torsion from edge conditions, openings, slab participation, construction loading, temporary shoring, and whether the beam is part of a lateral system.

Flexural Reinforcement Trial

Try three $20\ \text{mm}$ tensile bars at the bottom of the beam.

Area of one bar:

\displaystyle A_{bar}=\frac{\pi d_b^2}{4}

\displaystyle A_{bar}=\frac{\pi(20)^2}{4}=314\ \text{mm}^2

Total tensile steel:

A_s=3(314)=942\ \text{mm}^2

Reinforcement ratio:

\displaystyle \rho=\frac{A_s}{b_wd}

\displaystyle \rho=\frac{942}{300(540)}=0.00581=0.581\%

Use a simplified rectangular stress block to estimate nominal flexural strength. Compression block depth:

\displaystyle a=\frac{A_s f_y}{0.85 f'_c b_w}

\displaystyle a=\frac{942(500)}{0.85(30)(300)}=61.6\ \text{mm}

Lever arm:

\displaystyle z=d-\frac{a}{2}

\displaystyle z=540-\frac{61.6}{2}=509.2\ \text{mm}

Nominal moment capacity:

M_n=A_s f_y z

M_n=942(500)(509.2)=240\times10^6\ \text{N mm}=240\ \text{kN m}

Factored flexural resistance:

\phi_f M_n=0.90(240)=216\ \text{kN m}

Compare with demand:

216>161.0

Flexural strength passes this simplified review.

Margin ratio:

\displaystyle \text{margin}=\frac{216}{161.0}=1.34

The result is not a final code approval. The reviewer must still check ductility, minimum reinforcement, maximum reinforcement, bar spacing, development length, support anchorage, crack control, fire cover, lap splices, construction tolerances, and whether the assumed effective depth can actually be achieved.

Shear Reinforcement Trial

Average factored shear demand at the support is:

V_u=107.3\ \text{kN}

Use a simplified concrete shear contribution:

V_c=0.17\sqrt{f'_c}b_wd

where $f'_c$ is in MPa and dimensions are in millimetres.

V_c=0.17\sqrt{30}(300)(540)

V_c=151\ \text{kN}

Factored concrete contribution:

\phi_vV_c=0.75(151)=113\ \text{kN}

This is slightly above the simplified demand:

113>107.3

The numerical screen suggests concrete contribution alone may be near adequate. The design review should not stop there. Reinforced concrete shear can be brittle, and many standards require minimum shear reinforcement even when nominal concrete capacity appears sufficient.

Select two-legged $10\ \text{mm}$ stirrups at $250\ \text{mm}$ spacing as the trial detailing.

Area of one $10\ \text{mm}$ stirrup leg:

\displaystyle A_{leg}=\frac{\pi(10)^2}{4}=78.5\ \text{mm}^2

Two-legged stirrup area:

A_v=2(78.5)=157\ \text{mm}^2

Simplified stirrup contribution:

\displaystyle V_s=\frac{A_v f_{yv}d}{s}

\displaystyle V_s=\frac{157(500)(540)}{250}=170\ \text{kN}

Factored total shear resistance:

\phi_v(V_c+V_s)=0.75(151+170)=241\ \text{kN}

Since:

241>107.3

the trial shear reinforcement has substantial simplified strength margin. The review must still check code spacing limits, support-zone spacing, stirrup anchorage, beam depth effects, concentrated loads near supports, construction congestion, and whether the shear design should be governed by a different section location.

Serviceability Deflection Screen

Use service load:

w_s=26.82\ \text{kN/m}=26.82\ \text{N/mm}

Gross moment of inertia for the rectangular section is:

\displaystyle I_g=\frac{b_wh^3}{12}

\displaystyle I_g=\frac{300(600)^3}{12}=5.40\times10^9\ \text{mm}^4

Concrete elastic modulus estimate:

E_c=4700\sqrt{f'_c}

E_c=4700\sqrt{30}=25{,}700\ \text{MPa}

Because reinforced concrete cracks in tension, use a simplified effective stiffness:

I_{eff}=0.35I_g

I_{eff}=0.35(5.40\times10^9)=1.89\times10^9\ \text{mm}^4

For a simply supported beam with uniform load:

\displaystyle \delta_{max}=\frac{5w_sL^4}{384E_cI_{eff}}

\displaystyle \delta_{max}=\frac{5(26.82)(6000)^4}{384(25{,}700)(1.89\times10^9)}

\delta_{max}=9.3\ \text{mm}

A common preliminary serviceability limit is:

\displaystyle \delta_{limit}=\frac{L}{360}=\frac{6000}{360}=16.7\ \text{mm}

Since:

9.3<16.7

the beam passes this simplified deflection screen.

This result is sensitive to stiffness assumption. The review package should state whether long-term creep, sustained load, cracking, shrinkage, support rotation, slab participation, construction loading, partitions, finishes, and vibration need a more detailed serviceability model.

Detailing Review

The calculation assumes reinforcement works as intended. The detailing review checks whether that assumption can become a buildable beam.

Detailing item	Review question
tensile bar placement	Can three $20\ \text{mm}$ bars fit with required cover, spacing, and aggregate clearance?
effective depth	Does the drawing deliver $d=540\ \text{mm}$ after cover, stirrup diameter, bar diameter, and tolerance?
development length	Can bottom bars develop tension at critical sections and supports?
stirrup anchorage	Are hooks, bends, and closed ties compatible with the required shear path?
support zones	Are stirrup spacings tightened where shear and anchorage demand are high?
construction joints	Do joints avoid high-shear and high-moment regions or include verified preparation?
openings and embeds	Do sleeves, anchors, and penetrations avoid the assumed compression and tension zones?
concrete placement	Is the reinforcement cage congested enough to create honeycombing risk?
durability	Does cover match exposure, fire, corrosion, and inspection requirements?

If a detailing item fails, the project is not approved even if the simplified strength checks pass.

Construction Evidence Plan

The beam review should define inspection evidence before concrete is placed.

Evidence	Acceptance role
reinforcement shop drawings	confirm bar sizes, locations, laps, hooks, stirrups, and support details
pre-pour inspection photographs	prove reinforcement and embeds were placed before concrete hides them
cover survey or cover blocks	support durability and fire-resistance assumptions
concrete batch records	confirm specified mix, delivery time, and water additions
cylinder or cube test results	support compressive-strength assumption
curing record	supports strength gain, durability, and cracking assumptions
shoring and reshoring record	protects construction-stage load path
nonconformance log	records deviations, repairs, and engineer disposition
post-pour crack and honeycomb inspection	checks visible evidence of placement quality

The inspection plan is part of design quality. Reinforced concrete hides critical elements after placement, so missing evidence can become a structural uncertainty rather than a paperwork issue.

Failure-Mode Screen

A compact failure-mode screen helps decide where review effort belongs.

Failure mode	Cause	Control
flexural overstress	underestimated moment or insufficient bottom steel	independent load and moment check
brittle shear failure	inadequate stirrups or wrong support-zone detailing	shear design review and stirrup inspection
anchorage failure	bars not developed or laps placed poorly	development length and splice review
excessive deflection	cracked stiffness or creep underestimated	serviceability model and long-term check
corrosion initiation	cover, cracking, permeability, or exposure underestimated	cover, curing, drainage, and durability review
construction-stage cracking	shoring removed before adequate strength	field-cured strength and shoring release record
hidden placement defect	congested bars, honeycombing, or missing reinforcement	pre-pour inspection and non-destructive follow-up if needed

The most important control is not one formula. It is agreement between calculation, detailing, and field evidence.

RPN Review

Use a simple risk-priority-number screen for one critical review item: bottom tensile reinforcement placement.

RPN=S\times O\times D

Initial screen before inspection controls:

Factor	Value	Rationale
Severity $S$	$8$	Missing or misplaced bottom steel can compromise flexural capacity.
Occurrence $O$	$3$	Placement errors are not expected but are plausible on congested pours.
Detection $D$	$5$	After concrete placement, direct confirmation becomes difficult.

RPN_{initial}=8(3)(5)=120

With pre-pour inspection, bar-tag verification, photographs, and engineer hold point:

Factor	Value	Rationale
Severity $S$	$8$	Structural consequence is unchanged.
Occurrence $O$	$2$	Formal checks reduce likelihood.
Detection $D$	$2$	Reinforcement is inspected before it is hidden.

RPN_{controlled}=8(2)(2)=32

The RPN is not a structural approval method. It documents why inspection before concrete placement is a critical control.

Final Review Deliverable

The design review package should include:

Deliverable item	Required content
design basis note	code basis, load assumptions, material strengths, exposure, fire, and serviceability criteria
calculation sheet	load takeoff, reactions, moment, shear, reinforcement, and deflection checks
drawing markup	reinforcement sizes, cover, stirrups, development, supports, openings, and embeds
constructability note	bar spacing, congestion, pour sequence, shoring, and inspection hold points
risk register	key failure modes, controls, owner of each action, and residual risk
inspection and test plan	pre-pour checks, concrete tests, curing, shoring release, and nonconformance disposition
approval statement	accepted, accepted with conditions, revise and resubmit, or rejected

For the trial beam, the simplified review result is:

Check	Result	Review status
factored moment demand	$161.0\ \text{kN m}$	input to flexural check
factored flexural resistance	$216\ \text{kN m}$	passes simplified review
factored shear demand	$107.3\ \text{kN}$	input to shear check
factored shear resistance with stirrups	$241\ \text{kN}$	passes simplified review
service deflection	$9.3\ \text{mm}$	below $16.7\ \text{mm}$ screen
detailing	conditional	requires drawing and constructability review
construction evidence	conditional	requires pre-pour and concrete-quality records

The recommended approval status is:

Accepted for preliminary design development, subject to governing-code design, detailing review, serviceability refinement, construction inspection plan, and engineer approval of any field deviations.

Engineering Lessons

The first lesson is that reinforced concrete beam design is not a single moment calculation. Flexure, shear, deflection, crack control, anchorage, cover, constructability, and construction evidence must agree.

The second lesson is that simple calculations are useful when their limits are explicit. The moment and shear checks identify whether the trial section is plausible, but they do not replace code design, detailing rules, or inspection requirements.

The third lesson is that construction evidence is part of structural reliability. Reinforcement location, cover, concrete strength, curing, and shoring sequence can change the actual beam more than a small arithmetic refinement.

The final lesson is that a review package should end with a decision. Engineering calculations are valuable when they support a clear approval, rejection, or conditional action.

REF

Disciplines